By Greg Whitburn

Solar panels work through what is called a photovoltaic process – where radiation energy (photo) is absorbed and generates electricity (voltaic).

Solar Panel Diagram: A cell level view of how solar panels work.This is called a photovoltaic process.

Radiation energy is absorbed by semi conductor cells – normally silicon – and transformed from photo energy (light) into voltaic (electrical current).

When the sun’s radiation hits a silicon atom, a photon of light energy is absorbed, ‘knocking off’ an electron.

These released electrons create an electric current.

The electric current then goes to an inverter, which converts the current from DC (direct current) to AC (alternating current).

The system is then connected to the mains power or electricity grid.

Crystalline Silicon Solar Panels

Traditional systems, called crystalline silicon solar modules, involve wafers of refined silicon beneath sheets of glass. The panels are surrounded by a metal frame.

A solar panel installer connects crystalline silicon panels – made with silicon wafers, glass panelling, and a frame.

These are by far the most common solar panels. If you’ve come across a solar panel installation, chances are it uses crystalline silicon technology.

Crystalline silicon technology has been used for around 50 years, and was first developed for powering satellites in space.

Current off the shelf crystalline silicon systems are generally capable of converting up to about 18 % of solar radiation exposure into useable electricity. This is termed as a photovoltaic efficiency of 18%.

The main complaint of crystalline silicon is that the systems are expensive and bulky, installation requires a lot of wiring and labour, and that glass can be prone to damage.

Thin film solar panels

The new breed of solar technology is thin-film solar panels. Thin film is less bulky than crystalline silicon, and increasingly cheaper to produce.

New tech: Thin film solar panel cladding at the Solar Decathlon in Washington.

Thin-film solar energy systems currently have a lower photovoltaic efficiency than crystalline silicon – converting around 8% of radiation exposure – however the conductibility is expected to sharply rise as current research improves the method.

Thin-film solar panels work in the same photovoltaic manner as crystalline silicon modules, without the bulky wafers and glass panelling.

Amorphous silicon is a material used in some thin-film flexible solar panels, which can be moulded to essentially any surface such as roofs or walls.

Rethinking How Solar Panels Work – New Methods and Applications

Solar research and development has boomed around the world over the last few years. These include new photovoltaic conversion methods and application technology, large scale solar farms, and increasingly efficient technology.

Below are a few of these developments.

Stirling Energy Systems’ California plant has developed a new solar electricity production method.

They use the sun’s radiation to heat hydrogen gas, which spins a generator, producing electricity. This method has a reported expected efficiency of 30%.

Another development is the number of large scale solar farms, which has recently spiked.

There are now 56 large scale (20 megawatt or more capacity) solar farms, with at least 27 more in the planning or development stages.

One of the largest, the Montalto di Castro Solar Park in Italy, produces 40,000 megawatt hours per year, enough electricity to power around 13,000 Italian households.

American company Solar Roadways has recently been awarded a grant by the US Federal Highway Administration to develop a solar car park.

The idea is to cover the car park’s surface in solar panels, creating a vast surface area for clean electricity production.

Solar Roadways co-founder Scott Brusaw envisages the project spreading to roads once the technology and methodology has been developed with the carpark project.

Beyond the possibility of turning whole roads into electric grids, other features in the pipeline include built in de-icing mechanisms and LED lighting for driver visibility, as well as recharging stations for electric cars – all using free solar energy.

Another US company, Dow Chemicals, have developed thin-film solar roof tiles.

The solar roof tiles are physically like any other roof tile, and are nailed to the roof just like traditional tiles.

How the tile solar panels work is along the same concept as conventional solar – the tiles plug into each other to create an array, then an electrician connects the panels to an inverter, and into the mains power of the building.

By Greg Whitburn

In 2009, the average cost of solar panels for a 2kw system was $9,400-$21,000 USD – based on data spanning Germany, Japan, and the US.

The cost of solar panels can vary dramatically depending on your location, and the type and size of the system you purchase.

This article discusses the cost considerations involved with residential solar power, including recent cost stats, to give you an introduction before investigating the specifics for your location.

Current data about the cost of solar power have some inconsistency for a variety of reasons.

These reasons include a lack of standardized reporting due to the relative infancy of the solar industry, geographical differences in sun exposure, geographical differences in costs of equipment and solar panel installation, and different government policies.

A report on worldwide prices [1], published in Renewable & Sustainable Energy Reviews, estimates the average costs of recently installed systems (2009) at $7.70 per watt installed capacity in Germany, $4.70 per watt in Japan, and ranging from $5-$10.50 per watt across the United States [1][3]. The figures are for residential (2-5kW) systems, and before any government incentives.

On that basis, a 2Kw capacity solar panel system would cost between $9,400 and $21,000 installed – depending on your location.

2011 was a majorly turbulent year for the solar industry, with early indications showing average solar panel prices dropped by 50%.

Solar Power Cost Per kWh

A useful figure to use when looking at solar is cost per kWh, as this can be directly compared to your current power bill. A National Renewable Energy Laboratory report spanning 7 U.S states, gives a levelised cost of solar of between $0.28 and $0.46 per kWh for residential solar systems. This excludes the U.S federal tax credit and other subsidies [3].

Solar costs per kWh hour are calculated by dividing the total expected cost of a system (modules, inverters, installation etc) by the expected total energy output. Obviously there isn’t an ongoing per kWh cost as the electricity trickles in.

Government incentives for solar panels

The capital cost of solar panels must be considered within the context of government grants, subsidies, and loans.

Feed-in-tariffs are a government incentive used to mitigate the high capital cost of solar energy.

Many countries already have, or are currently developing policies to encourage renewable energy. These include subsidies, rebates, and tax credits for the capital cost of installing solar panels. Incentives differ between countries and states.

An example: the levelised cost of solar electricity in the 7 U.S states calculated earlier drops to from between $0.28 and $0.46 per kWh to between $0.16 and $0.31 per kWh with the federal investment tax credit [3].

Many U.S residents are eligible for additional federal and local government subsidies on top of the ITC.

Another widely used incentive is feed-in tariffs. These relate to money paid for putting solar-generated energy back into the electricity grid. If a resident’s solar panels produce more energy than is required, it can be connected to the grid and sold to electricity companies.

Feed in tariffs are designed to encourage alternative energy production by guaranteeing a fixed per watt hour price – often above the current market rate. Current capital costs mean solar power is often more expensive to produce than conventional power (grid disparity), so governments top-up market rates to make solar production viable.

Electricity Bill Savings with Solar Energy

Money saved on electricity through smaller or eliminated electricity bills should be factored into your cost of solar panels calculation. Have a look at your last few electricity bills and calculate your expected energy reduction – factor the $30, $50, or $100 expected monthly saving into your solar cost analysis.

Freedom from the fluctuations of electricity prices and from the international politics of fossil fuels is an enormous future cost-benefit of solar energy.  As fossil-fuel energy prices continue to rise, solar power users will remain unaffected.

Carbon emission taxes are another factor affecting the long term cost of solar power. As we struggle with the burgeoning climate change crisis, countries are imposing their own per kg carbon taxes and emissions trading schemes to curb pollution. These taxes will increasingly make fossil fuel generated electricity more expensive, thus make the comparative cost of solar cheaper.

Grid Parity of Solar Panels

What we’re talking about above is “grid parity.” Grid parity is the term used to compare the cost of solar power and traditional power. Reaching grid-parity means it costs the same dollar amount to produce a KWh of solar power as it costs to produce a KWh of traditional electricity, e.g coal produced. Solar power has not yet reached grid parity.

Lack of grid parity is a major roadblock in clean energy becoming mainstream – it’s not financially cost effective compared to the model we’re currently using.

Data from 58,000 Californian installations shows the installed cost of solar panels dropping.

However, grid parity is expected in the next few years in places like California and Hawaii [1], followed by other locations as the technology rapidly develops and economies of scale see cost decreases.

Solar power is in relative infancy, and over the past few years the technology and cost developments have accelerated dramatically. A Lawrence Berkeley National Laboratory research paper shows that among 58,000 installations in various California solar initiatives, the average cost of solar panels dropped from $12.15/watt in 1998 to $8.09 in 2009 [4].

Furthermore, the report showed preliminary findings of a $1/watt reduction between 2009 and 2010 for systems installed in the California Solar Initiative [4].

Price of Solar Photovoltaics Plummets in 2011

While it’s too early for broad global assertions, 2011 was a turbulent year for the photovoltaic manufacturing industry, with average solar panel prices dropping around 50% [5][8].

Major contributing factors include oversupply and the growth of extremely competitive Chinese manufacturers being able to leverage cheap labour and cost-efficient manufacturing processes (materials, factories, economies of scale etc) [7].

2011 also saw record numbers of photovoltaic installations in the US, the insolvency of major US manufacturers Evergreen Solar and Solyndra (with a reported $1 billion of sales contracts) [6], and a backpeddling on government tarrifs in European countries.

This highlights the rapid cost reduction developments taking place in the industry, the power of economies of scale, and the sometimes fickle nature of young and rapidly expanding markets.

Geographic Considerations – Cost of Importing Solar Panels

Geographical location is an important factor. Beyond the obvious fact that some locations get more sun exposure, location has a big impact on the cost of solar panels due to importing costs and lack of competition in some areas.

If you live in an area where solar panels are not yet common, it’s likely that prices will be higher – both in terms of purchasing the hardware, installation, and the government incentives available.

If you live in such a location, get plenty of quotes and investigate all options – such as using a commercial installer, buying a kitset and getting a solar-experienced builder to do the installation, looking for a syndicate of others to do a bulk import, and finding out what government programmes or incentives are available.

Balance of System and Net Metering Struggles

A majorly problematic area in terms of bringing down costs of solar is the balance of system costs.

These are the additional components required for a system – inverters, cabling etc.

While solar panels are constantly becoming more competitive, there has been little movement on the price of peripherals. This is a major concern and needs to be addressed if solar is going to achieve true market competitiveness [9].

Furthermore, net metering (selling power back to the grid) is an exciting potential of solar which has had its own challenges. Particularly in the US, it has been reported that while power companies may have the ability offer net metering, the required two-way-meters aren’t necessarily being installed in homes – meaning some private owners may not be getting paid for the power they put back into the grid [9].

Some power companies are reportedly introducing “standby” fees for customers who are generating their own solar power. These are where customers are charged a monthly fee for being grid connected, regardless of whether or not they use any grid power – cutting away at savings made through solar panels [9].

These are important kinks or obstructive forces that need to be addressed if solar is to continue its momentum in becoming a legitimate and accepted piece of the energy puzzle [9].

Criticism of Solar Subsidies and Expense

Alternative energy production methods are commonly criticized as being idealistic but not cost-effective.

An interesting consideration regarding cost-effectiveness and subsidies is that in its early years, nuclear fission technology received subsidy support of $19 per kilo watt hour produced, compared to $8.90 per kilo watt hour for solar, and just $0.57 per kilo watt hour for wind power [2].

This highlights how subsidy support in the early years can result in better, more cost effective, and more socially beneficial technology in the future.

References

By Greg Whitburn

The term photovoltaic literally means light producing electricity. Turning photo (light) into voltaic (electrical current), is the basis of how solar panels work. So, photovoltaic efficiency refers to how efficiently a solar cell or solar module produces electricity.

Photovoltaic efficiency describes the efficiency or conductivity of solar panels – the percentage of radiation (sun) energy that can be converted into electrical energy.

Currently, photovoltaic efficiency of silicon crystalline solar panel modules is up to 22% [1] – meaning those systems convert up to 22% of the sun’s energy they’re exposed to into useable electricity. Crystalline silicon was the first mainstream solar technology, and continues to be the most commonly used.

New technology silicon thin-film photovoltaic module efficiency is up to 8% [1]. Although thin-film is less efficient, its advantages are that it’s less bulky, has more applications, and is easier and cheaper to produce and install.

It’s important to note that these records are for solar panel module efficiency (a circuit of multiple cells), not individual solar cells. Individual solar cell efficiency records are higher but less consistent.

Thin film solar panels are expected to become vastly more efficient as the solar and alternative energy race heats up.  Alta Devices Inc have developed a thin-film solar cell that’s achieved 28.4% efficiency. It uses gallium arsenide (GaAs) as a conductor, rather than the traditional silicon based conductors. [2]

Photovoltaic efficiency not the only factor

Additional factors affect how much electricity a solar panel module will actually produce. Technical photovoltaic efficiency doesn’t necessarily mean solar panel efficiency.

Angle and location also weigh in on the efficiency of solar panels. You’ll need to figure out the optimal placement for your location to get maximum sun exposure hours.

In New Zealand, the north facing side of the house gets most sun exposure so New Zealanders install solar panels to face north, whereas solar panels in the United States generally face south.

Boosting efficiency of solar panels with sun tracking – As the sun moves, the panels’ change angle.

Concentrated Solar – Large angled mirrors concentrate the sun’s radiation onto a few solar cells.

Solar tracker technology is another development which increases overall solar panel efficiency.

Commercial solar farms like the Montalto di Castro solar park in Italy use sun tracking systems to maximize the amount of time that solar panels are exposed to the sun’s radiation [3].

Similar systems are available for smaller scale private solar panels, however are less popular than static due to increased setup costs and maintenance.

Multijunction solar cells are another exciting new solar innovation. Individual solar cells (normally silicon) only react to a certain range of light depending on their molecular makeup – some silicon conducts and reacts to ultra-violet light, while other silicon reacts to infra-red light.

Multijunction solar cells combine layers of differently tuned silicon – so a single multijunction cell covers greater range of light and thus has a greater electricity production potential.

Concentrating solar is another technology increasing the efficiency of solar panels. This involves using mirrors to concentrate sun radiation on a single cell. Concentrated solar exposure equals greater power production.

Measures Beyond Efficiency of Solar Panels

Other measurements to be aware of when researching solar power are photovoltaic capacity and watt hours.

Photovoltaic capacity refers to the maximum power output a solar panel module is designed to produce – if the solar module were exposed to constant and direct radiation.

Photovoltaic power capacity ranges from large solar farm installations, such as Montalto di Castro with a peak capacity of 24 mega watts [3], to small residential solar modules with a capacity of 180 watts.

It’s important to note that photovoltaic efficiency and capacity of solar panels are useful as indications only – they’re not measures of actual production.

Time of day, amount of sunshine or cloud, location, and numerous other factors will influence actual solar power production levels. 

For these reasons, worldwide solar production is estimated to be around 25% of peak capacity levels.

Watt hours is the measurement of actual electricity produced.

Watt hours is arguably the most useful indication of a solar installation’s value as it can be directly compared to watt hours of electricity produced by traditional fossil fuel energy production or to how many watt hours a town or individual family uses.

Looking at watt hours presents a tangible cost comparison that solar panel efficiency doesn’t. The Montalto di Castro solar park for example produces around 40,000 mega watt hours (MWh) per year – enough to supply approximately 13,000 Italian houses [5].

Furthermore, by looking at expected watt hour generation, a cost per kWh figure can be calculated and compared.

Article References

13 Fundamental Advantages and Disadvantages of Solar Energy

By Greg Whitburn

Solar energy is becoming increasingly popular as the world begins to take notice of the burgeoning carbon emission problems that come with burning fossil fuels. But why all the fuss?

Nay-sayers have become less and less vocal as solar energy’s popularity has grown increasingly unhindered. Below I will discuss the advantages and disadvantages of solar energy.

Advantages of Solar Energy

No green house gases

Advantages and disadvantages of solar energy: The major benefit of solar is avoiding green house gases that fossil fuels produce.

The first and foremost advantage of solar energy is that it does not emit any green house gases.

Solar energy is produced by conducting the sun’s radiation – a process void of any smoke, gas, or other chemical by-product.

This is the main driving force behind all green energy technology, as nations attempt to meet climate change obligations in curbing emissions.

Italy’s Montalto di Castro solar park is a good example of solar’s contribution to curbing emissions. It avoids 20,000 tonnes per year of carbon emissions compared to fossil fuel energy production.

Infinite Free Energy

Another advantage of using solar energy is that beyond initial installation and maintenance, solar energy is one hundred percent free.

Solar doesn’t require expensive and ongoing raw materials like oil or coal, and requires significantly lower operational labor than conventional power production.

Lower costs are direct as well as indirect – less staff working at the power plant as the sun and the solar semi conductors do all the work, as well as no raw materials that have to be extracted, refined, and transported to the power plant.

Decentralization of power

Solar energy offers decentralization in most (sunny) locations, meaning self-reliant societies.

Oil, coal, and gas used to produce conventional electricity is often transported cross-country or internationally. This transportation has a myriad of additional costs, including monetary costs, pollution costs of transport, and roading wear and tear costs, all of which is avoided with solar.

Of course, decentralization has its limits as some locations get more sunlight than others.

Going off the grid with solar

Solar Barn: Going off grid is a huge advantage of solar power for people in isolated locations.

Solar energy can be produced on or off the grid.

On grid means a house remains connected to the state electricity grid. Off grid has no connection to the electricity grid, so the house, business or whatever being powered is relying solely on the solar or solar-hybrid.

The ability to produce electricity off the grid is a major advantage of solar energy for people who live in isolated and rural areas. Power prices and the cost of installing power lines are often exorbitantly high in these places and many have frequent power-cuts.

Many city-dwellers are also choosing to go off the grid with their alternate energy as part of a self-reliant lifestyle.

Solar jobs

A particularly relevant and advantageous feature of solar energy production is that it creates jobs.

The EIAA states that Europe’s solar industry has created 100,000 jobs so far.

Solar jobs come in many forms, from manufacturing, installing, monitoring and maintaining solar panels, to research and design, development, cultural integration, and policy jobs.

The book Natural Capitalism has a very appropriate view of the employment benefits of green design and a prudent approach to using resources.

The book proposes that while green technology and increased employment cost alot of money, much greater money can be saved through simple but drastically improved resource efficiency.

With solar energy currently contributing only an estimated 4% of the world’s electricity, and an economic-model where raw materials don’t have to be indefinitely purchased and transported, it’s reasonable so assume solar jobs are sustainable if the solar industry can survive the recession.

Solar’s avoidance of politics and price volatility

One of the biggest advantages of solar energy is the ability to avoid the politics and price volatility that is increasingly characterizing fossil fuel markets.

The sun is an unlimited commodity that can be adequately sourced from many locations, meaning solar avoids the price manipulations and politics that have more than doubled the price of many fossil fuels in the past decade.

While the price of fossil fuels have increased, the per watt price of solar energy production has more than halved in the past decade – and is set to become even cheaper in the near future as better technology and economies of scale take effect.

Furthermore, the ever-abundant nature of the sun’s energy would hint at a democratic and competitive energy market – where wars aren’t fought over oil fields and high-demand raw materials aren’t controlled by monopolies.

Of course, a new form of politics has emerged with regard to government incentives and the adoption of solar, however these politics are arguably incomparable to the fossil fuel status quo.

Saving eco-systems and livelihoods

Because solar doesn’t rely on constantly mining raw materials, it doesn’t result in the destruction of forests and eco-systems that occurs with most fossil fuel operations.

Destruction can come in many forms, from destruction through accepted extraction methods, to more irresponsible practices in vulnerable areas, to accidents.

Major examples include Canada’s tar sands mining which involves the systematic destruction of the Boreal Forest (which accounts for 25% of the world’s intact forest land), and creates toxic by-product ponds large enough to see from space [1].

The Niger Delta is an example where excessive and irresponsible oil extraction practices have poisoned fishing deltas previously used by villagers as the main source of food and employment, creating extremely desperate poverty and essentially decimating villages [2].

A more widely known, but arguably lower human-cost incident is the 2010 BP oil spill in the Gulf of Mexico. It killed 11 people and spilled 780 thousand cubic meters of crude oil into the sea.

The best is yet to come

Solar technology is currently improving in leaps and bounds. Across the world, and particularly in Europe, savvy clean technology researchers are making enormous developments in solar technology.

What was expensive, bulky, and inefficient yesterday, is becoming cheaper, more accessible, and vastly more efficient each week.

Disadvantages of Solar Energy

Solar doesn’t work at night

Obviously the biggest disadvantages of solar energy production revolve around the fact that it’s not constant. To produce solar electricity there must be sunlight. So energy must be stored or sourced elsewhere at night.

Beyond daily fluctuations, solar production decreases over winter months when there are less sunlight hours and sun radiation is less intense.

Solar Inefficiency

A very common criticism is that solar energy production is relatively inefficient.

Currently, widespread solar panel efficiency – how much of the sun’s energy a solar panel can convert into electrical energy – is at around 22%. This means that a fairly vast amount of surface area is required to produce a lot of electricity.

However, efficiency has developed dramatically over the last five years, and solar panel efficiency should continue to rise steadily over the next five years.

For the moment though, low efficiency is a relevant disadvantage of solar.

Solar inefficiency is an interesting argument, as efficiency is relative. One could ask “inefficient compared to what?” And “What determines efficiency?” Solar panels currently only have a radiation efficiency of up to 22%, however they don’t create the carbon by-product that coal produces and doesn’t require constant extraction, refinement, and transportation – all of which surely carry weight on efficiency scales.

Storing Solar

Solar electricity storage technology has not reached its potential yet.

While there are many solar drip feed batteries available, these are currently costly and bulky, and more appropriate to small scale home solar panels than large solar farms.

Solar panels are bulky

Solar panels are bulky. This is particularly true of the higher-efficiency, traditional silicon crystalline wafer solar modules. These are the large solar panels that are covered in glass.

New technology thin-film solar modules are much less bulky, and have recently been developed as applications such as solar roof tiles and “amorphous” flexible solar modules. The downfall is that thin-film is currently less efficient than crystalline wafer solar.

One of the biggest disadvantages of solar energy – COST

The main hindrance to solar energy going widespread is the cost of installing solar panels. Capital costs for installing a home solar system or building a solar farm are high.

Particularly obstructive is the fact that installing solar panels has large upfront costs – after which the energy trickles in for free.

Imagine having to pay upfront today for your next 30 years worth of power.

That’s an incredibly disadvantageous feature of solar energy production, particularly during a time of recession.

Currently a mega watt hour of solar energy costs well over double a mega watt hour of conventional electricity (exact costs vary dramatically depending on location).

All is not lost though – nuclear is a good example (economically) of energy production that was initially incredibly expensive, but became more feasible when appropriate energy subsidies were put in place.

Solar Energy Gets People Talking

One of the accompanying advantages and disadvantages of solar energy and other green tech is that they’re making us re-assess how things are valued in society, and how things like economics, environment, and investment are handled.

There is debate and polarization of perspectives and interests.

While not everybody is in favor of solar (some more aggressively than others), the fact that there is discussion about the validity of the status quo – the monopolistic nature of many industries, the problems with solely focusing on economics, and environmental disregard – is a fascinating development, a development that some may term an ideological revolution.

At a practical level, many governments and state authorities are encouraging solar use through incentives such as subsidies, rebates and tariffs. California is a good example of how such measures can work.

Spain highlights the importance of long-term consideration with such incentives, and how they can fail if not handled correctly or if circumstances change, such as the global financial crisis.

Factors such as cheaper materials and installation as demand grows will make solar more affordable in the future, but for the moment, the fact is that producing solar electricity is financially expensive compared to conventional methods.

By Greg Whitburn

Water heating is a great place to begin cutting back on fossil fuel consumption. Water heating is very energy intensive, and solar offers a solution that can be implemented fairly easily in individual homes.

As a general rule, heating water accounts for 30% of most peoples’ energy costs.

There are a number of options for a solar water heater; from purchasing ready-to-roll systems to making your own.

The basic model is that the sun’s energy is used to heat water. The process is called solar-thermal – conducting the sun’s energy as heat, as opposed to photovoltaic – converting the sun’s energy into electricity.

How do solar water heaters work?

Roof Mounted Solar Water Heater – Cold water flows into the tubes, is heated by the sun, and flows out to an insulated cylinder.

A module of solar tubes is installed on a roof or sun-exposed area. Cold water passes through the tubes and is heated by the sun, flowing to an insulated cylinder once heated.

Alternate systems use chemicals such as glycol, which are easy to heat. The glycol flows through the solar tubes, then heats the water.

Most solar water heating systems require an electric powered backup heater known as a booster. The booster kicks in to further heat the water and kill any bacteria, or at night time and cloudy days when the system isn’t getting enough sun energy.

Some systems carry the water to a storage cylinder inside the house, whereas some storage tanks are outside (often connected to the solar module), or in the ground. The advantage of having the tank inside is better insulation. The advantage of outside is that installation is simpler and cheaper for retro-fitting.

There are also differences in how the water gets to the cylinder. Convection solar water heating systems use convection current principle – that hot water rises – to transfer hot water to the cylinder. This method stores the hot water above the module and doesn’t require any mechanics or electricity. Pump based systems use an electrical pump to transfer the water to the cylinder.

Buy solar water heaters or make your own?

Solar water heaters can be purchased as a package and installed by professionals or you can make your own.

The main advantage of a professional job is knowledge and experience; your solar water heater system will be tidy, installed with best practice, made from materials that have been tested and proven to last, be installed in the optimal spot for maximum sun exposure, and will likely come with some type of guarantee.

The downfall of using professionally made solar heating systems is expense.

There are large communities of people on the net who make their own alternative energy mechanisms, and many of them have instructions for building your own solar water heater.

It’s highly recommended you do some due diligence before diving in to either option. Installation is a big task so you only want to do it once.

Things to consider

Price: Never just go for the cheapest option, but have a look around and get a feel for prices, including installation and maintenance fees. Often sourcing locally is the best option as there’s easier access to follow up support, but have a look on the internet as well and get a broad gauge of the prices and packages available.

Kitset or pay for install and maintenance? If you’re an experienced tradesman you may be able to purchase from a company then install a solar water heater yourself. In this case you’ll be able to save a lot of money, but check with your dealer whether they offer product-only sales.

How much hot water do you need? A family of four uses a lot more hot water than a family of two, so make sure you’re thinking literage when you’re looking at your solar hot water options.

Solar company reputation: Take your time to get as much information as you can about your chosen solar hot water company. Look on a number of websites and read as many customer reviews as you can.

Your solar company should be happy to offer a free consultation before you commit. A good thing to consider is whether they can answer your questions without hassle. If they can answer your questions over the phone and without having to look things up every two seconds it’s one indicator that the staff have a good knowledge of solar and offer good customer service. If they tell you to just read their website it may not be a great indicator. Also remember to compare maintenance service and guarantees.

DIY solar reputation: Likewise if you’re building a DIY solar water heater, have a look around and scope out the best plans. Look for plans that have been used by many people and include good feedback. Join forums and learn from the experience of other alternative energy-ites. It’s also a good idea to discuss any plans with a builder, plumber or electrician, and research your local consent requirements.

by Clint Ouma

The word hybrid is used to refer to something made by combining different elements [1]. Modern science has seen dramatic advances in hybrid technology, giving birth to hybrid cars such as the Toyota Prius [2] and incorporating information and communications technology (ICT) systems that automate smart-houses and eco homes.

Similarly, hybrid energy systems have been designed to generate electricity from different sources, such solar panels and wind turbines.

Hybrid energy systems often consist of a combination between fossil fuels and renewable energy sources, and are used in conjunction with energy storage equipment (batteries).

This is often done either to reduce the cost of generating electricity from fossil fuels or to provide back up for a renewable energy system, ensuring continuity of power supply when the renewable energy source fluctuates.

One of the biggest downfalls of renewable energy is that energy supply is not constant [3]; sources like solar and wind power fluctuate in intensity due to the weather and seasonal changes [3].

Therefore, a reliable backup system is necessary for renewable energy generating stations that are not connected to a national power grid.

These systems consist of a variety of power control methods and storage equipment which include battery banks and diesel generators among others.

The power systems that are connected to the national grid don’t have this problem because, in most cases, there are many different sources of power contributing to the national electricity supply.

Different Hybrid Power Technologies

There are several types of hybrid energy systems such as wind-solar hybrid, solar-diesel, wind-hydro and wind-diesel.

The design of a system or the choice of energy sources depends on several considerations.

The factors affecting the choice of hybrid power technology can also tell us why people use hybrids and some of the advantages. The main factors are cost and resources available.

The cost hybrid power technology greatly affects the choices people make, particularly in developing countries.

This also depends on the aim of the project. People who are planning to set up a hybrid energy project for their own use often focus on lowering the total investment and operational costs while those planning to generate electricity for sale focus on the long-term project revenue.

As such, systems that incorporate hydrogen storage and fuel cells [4] [5] are not very common with small scale projects. The viability of one hybrid energy system over another is usually pegged on the cost of generating each kilowatt.

The availability of the natural resources plays an enormous part when selecting the components of a hybrid energy system – the right power generation location and method must be chosen.

Often, a hybrid system is opted for because the existing power resource is not enough to generate the amount of power needed – which is often the case when using micro-hydro plants.

In some developing countries, such as parts of Ethiopia, a wind-solar hybrid power system, consisting of wind turbines and solar photovoltaics was found to be most viable. This was because the wind resource alone was not sufficient to meet the electric load. Solar P.V. cells were very expensive, so it wasn’t feasible for the project developers to use solar power alone [6].

Hybrid systems are most suitable for small grids and isolated or stand-alone systems as hybrid power generation is, by definition, a solution for getting around problems where one energy source isn’t sufficient.

The popularity of hybrid energy systems has grown so much that it is now a niche-industry in itself – with custom systems being engineered for specific functions. For instance, Enercon, a German wind power company, has come up with unique factory-designed hybrid power technology, including the world’s first hybrid wind-diesel powered ship, the E-Ship 1 [7].

Article References

By Clint Ouma

The energy game has changed dramatically over recent years and has seen the emergence of some major, fast growing, and innovative solar energy companies.

As solar and other renewables become the major piece of the energy puzzle, these companies will play an unprecedented role in changing the global energy system with clean power, bringing electricity to developing nations, and innovating energy-generating applications that fit a diverse range of functions and needs.

Below we look at some of the top solar energy companies today.

Suntech

Solar panels on China’s Bird’s Nest Olympic stadium were supplied by one of the world’s top solar companies, Suntech.

Suntech was one of China’s first solar energy companies and is now the world’s largest silicon solar panel producer.

The company has grown quickly since its establishment in September 2001 and now has a presence in 80 countries worldwide and a dynamic research and development team spread across five countries.

One of the company’s key milestones was winning a contract to supply the solar panels for the revolutionary Bird’s Nest 2008 Olympics Arena in Beijing – a 130 kW solar installation.

The business has also successfully penetrated the western market by establishing its first U.S. factory in Arizona on January 2010.

Suntech’s technology now ranks among the best in the world after attaining a photovoltaic conversion efficiency of 19% for mono crystalline solar cells and 17% for polycrystalline photovoltaic cells in 2009 and attained the 2 GW (gigawatt) mark in 2011.

First Solar

Since its inception in 1999, First Solar has grown such that now powers 2,864,816 homes and displaced nearly 4 million Metric Tons of CO2 (as of April 2012) [2].

Through continuous research and development, the company has won several awards for ground breaking work in the solar energy industry.

They’ve balanced efficiency and cost to develop the lowest cost solar panels per watt – with the price of less than 1$/watt.

Although First Solar uses cadmium tellurium (Cd-Te) panels, which are less efficient than the crystalline panels, they have been able to consistently set world records for efficiency of the Cd-Te panels, first at 13.4% and now at 14.4% [2].

The First Solar power systems are particularly attractive because they have the fastest energy payback time when compared to all other photovoltaic PV systems in the market.

Sharp Solar

Sharp Solar is a subsidiary business of the Japanese electronics giant, Sharp.

The company has been developing solar power solutions for more than 50 years and has secured a large consumer base and is well trusted in the industry.

Sharp Solar was the first of all solar energy companies to achieve 2 GW of solar cells.

They have repeatedly broken world records for solar cell conversion efficiency achieving 14.4% for polycrystalline photovoltaic module in 2008 and 35.8% for triple junction compound solar cells.

The company’s development has been greatly supported by the fast growth of the local Japanese solar market.

Yingli Green Energy

Cheap production costs are a common characteristic of most Chinese manufacturing companies.

Yingli Green Energy Company has taken advantage of these cheaper labor and material costs to focus on innovation in order to maintain a competitive edge.

The company develops products across the entire photovoltaic value chain.

These products include poly silicon material, ingots, wafers, solar cells and photovoltaic modules. In this way, the company has been able to serve a wide range of clients and offer a variety of solutions to each.

Global Solar Energy Company Trends

Significant growth in the Chinese solar energy Industry has caused the prices of solar panels to drop worldwide and the latest reviews have it that seven out of the ten top solar energy companies in the world are Chinese [6].

Recent trends show that whereas Chinese solar companies are growing exponentially, some major American companies have exhibited the opposite result.

In the USA, two major solar companies which in 2009 had been among the top in the world, Solyndra in California and Evergreen Solar in Massachusetts [7] [9], filed for bankruptcy in 2011 [8].

Solyndra was a champion of the innovative Copper Indium Gallium Selenium (CIGS) solar panels, with a focus on rooftop modules. Solyndra was able to attract investors and governmental support, with sales contracts reportedly worth over $1 billion [7].

With the drastic drop in costs of solar panels over the last 3 years, Solyndra’s business model became unfeasible and the company could no longer compete, despite further government support through the US Energy Department’s loan guarantee program [9].

Article References

Solar Roof Tiles – Bringing Photovoltaic Technology into Roof Shingles

by Jenny Griffin

Solar energy is typically harnessed through the use of photovoltaic solar panels made of crystalline silicon, which are attached to a roof or other structure.

These panels are positioned facing the sun (south in the northern hemisphere, north in the southern hemisphere) or may be placed on a solar tracking system that follows the sun.

Because silicon solar panels are bulky, they can be unsightly, and are also prone to damage in areas that experience strong winds.

However, the recent introduction of photovoltaic roof tiles offers an ingenious alternative to bulky photovoltaic panels for harnessing energy from the sun.

Photovoltaic roof tiles are either made from regular crystalline silicone-based materials, or from thin-film solar cells, manufactured from layers of very thin semiconductor materials, such as amorphous silicon, or from other materials such as cadmium telluride, or copper indium gallium diselenide (CIGS).

The latter are thin, flexible, and durable, and ideally suited for use as a roof tile substitute that offers a protective roof cover, while drawing energy from the sun to provide your home with power. [1]

How Photovoltaic Shingles Work

Photovoltaic shingles work on the same principal as regular crystalline solar panels. Photovoltaic literally means ‘light energy’.

The semiconductor photovoltaic cells absorb energy radiated from sunlight, which is then transformed from light (photo) energy into electric (voltaic) current. When energy from sunlight strikes the semiconductor material in the photovoltaic cells, a photon of light energy is absorbed, releasing an electron, which produces an electric current.

The current produced is direct current (DC), but as homes and business run on alternating current (AC), this needs to be converted by an inverter for domestic use. Once the current has been converted to alternating current, it can be connected to the main power board of a building to provide power locally, or it can even be connected to the electricity grid to provide power further afield. [2]

Installing Solar Roof Tiles

A regular solar panel typically consists of 40 photovoltaic cells that are installed in arrays of between 10-20 panels in a typical home system.

The panels can be installed onto an existing roof structure, or placed anywhere on the property to take optimal advantage of available sunlight. Photovoltaic roof tiles on the other hand, form an integral part of the roof structure, replacing regular roof tiles to serve a dual purpose of both repelling water, snow, hail, and wind, while absorbing the energy of the sun as a source of power.

While replacing existing roof tiles with photovoltaic tiles may be rather costly, when constructing a new home this may be quite cost effective in the long term, as it saves on the cost of roof tiles, and offers dramatic savings on energy costs.

Types of Photovoltaic Roof Shingles

Photovoltaic roof shingles are available in silicon or thin-film solar materials.

With energy efficiencies as high as 20.3% attained by silicon photovoltaic cells [3], silicon roof tiles, like silicon solar panels, are more energy efficient than thin-film solar tiles, but they are expensive, and take a long time to install.

Thin-film solar tiles are a recent innovation that are more affordable than silicon roof tiles, as they are cheaper to produce.

They are easy to install, cutting the installation time down by half – to around ten hours, which offers a further cost saving in terms of time and labor.

With ongoing research and development, thin-film photovoltaic roof tiles are catching up in terms of energy efficiency.

A new record of 19.9% efficiency has been attained for CIGS thin-film solar cells by researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory [3].

This improved energy efficiency, together with the affordability and ease of installation, may make thin-film photovoltaic roof tiles the photovoltaic option of choice for solar power installations in the very near future.

Article References

As of 2012, the Montalto di Castro solar park is the largest photovoltaic power station in Italy, producing more than 40,000 MWh of electricity per year.

It was developed and is operated by SunRay Renewable Energy, and its modules produced by SunPower.

The solar park was completed in the winter of 2010, then sold to a consortium of investors.

Montalto di Castro uses sun-tracking technology – changing the angle of the solar panels with the sun for optimal radiation exposure.

The park contains 80,000 modules, with a peak installed capacity of 24 megawatts.

It’s located located around 100km from Rome, in the Lazio Region of Italy.

The construction of the Montalto di Castro solar park took place in 4 stages. It took eight months and approximately 250 workers.

According to the SunPower website, the solar park avoids 22,000 tons of CO2 annually and produces enough solar generated electricity to power 13,000 homes.

Article References

SunPower. Largest Solar Power Plant in Italy Completed. Retrieved from http://us.sunpowercorp.com/about/newsroom/press-releases/?relID=23297

Wikipedia. Solar Power in Italy. Retrieved from http://en.wikipedia.org/wiki/Solar_power_in_Italy

SMA. Solar Park Montalto di Castro. Retrieved from http://www.sma.de/en/products/references/solar-inverters/isolator/solar-park-montalto-di-castro.html

Solar trackers change the tilt of solar panels as the sun moves across the sky.

A solar tracker is a system whereby solar photovoltaic panels are tilted throughout the day to follow the sun – retaining the best angle for maximum radiation exposure.

Solar modules are mounted on tracking frames, connected to a solar actuator – which acts like a hydrolic lift or extender.

As the sun moves across the sky, the actuator extends and moves the solar panel in order to keep the optimal angle with the sun.

Using a solar tracker is becoming increasingly popular in both domestic and utility scale systems as it boosts the overall efficiency of solar panels.

The LINAK Solar Park in Denmark found that by adding trackers to their solar modules, they could get 30-40 percent additional electricity output.

The solar park was a green initiative of the LINAK company, setup next their headquarters. It is expected to generate around 90,000 kilowatt hours per year.

Many large utility solar parks are also using solar tracker systems, such as Italy’s 80,000 module Montalto di Castro.

Article Reference

1767, First Solar Collector
In the year 1767 a Swiss scientist named Horace-Benedict de Saussure created the first solar collector – an insulated box covered with three layers of glass to absorb heat energy. Saussure’s box became widely known as the first solar oven, reaching temperatures of 230 degrees fahrenheit.

1839, Photovolataic Effect Defined
In 1839 a major milestone in the evolution of solar energy happened with the defining of the photovoltaic effect. A French scientist by the name Edmond Becquerel discovered this using two electrodes placed in an electrolyte. After exposing it to the light, electricity increased.

1873, Photo Conductivity of Selenium
In 1873, Willoughby Smith discovered photoconductivity of a material known as selenium. The discovery was to be further extended in 1876 when the same man discovered that selenium produces solar energy. Attempts were made to construct solar cells using selenium. The cell did not work out well but an important lesson was learned – that solid could convert light into electricity without heat or moving parts. The discovery laid a strong base for future developments in the history of solar power.

1883-1891 Light Discoveries and Solar Cells
During this time several inventions were made that contributed to the evolution of solar energy use. First in 1893 the first solar cell was introduced. The cell was to be wrapped with selenium wafers. Later in 1887 there was the discovery of the ultraviolet ray capacity to cause a spark jump between two electrodes. This was done by Heinrich Hertz. Later, in 1891 the first solar heater was created.

1908, Copper Collector
In 1908 William J. Baileys invented a copper collector which was constructed using copper coils and boxes. The copper collector was an improvement of the earlier done collector but the only difference was the use of copper insulation. The improvements of the invention are being used to manufacture today’s equipments.

1916, Photoelectric Effect
With Albert Einstein publishing a paper on photoelectric effect in 1905 still there was no experimental evidence about it. In 1916 a scientist known as Robert Millikan evidenced the photoelectric effect experimentally.

1947, Solar Popularity in the US
Following the Second World War, solar power equipment started being popular among many people in the USA. There was a huge demand of solar energy equipment.

1958, Solar Energy In Space
Solar power was used to power space exploration equipment such as satellites and space stations. This was the first commercial use of solar energy.

1959-1970, Efficiency of Solar Cells and Cost
During the period between 1959 and 1970 there was major discussion about the efficiency of solar cells and reduction of costs. Up to that time the efficiency of the solar cells was only 14% and was not comparable to the high cost of producing cells. However in the 1970′s, Exxon Corporation designed an efficient solar panel which was less costly to manufacture. This was a major milestone in the history of solar energy.

1977 Governments Embrace Solar Energy
In 1977 the US government embraced the use of solar energy by launching the Solar Energy Research Institute. Other governments across the world soon followed.

1981, Solar Powered Aircraft
In 1981, Paul Macready produced the first solar powered aircraft. The aircraft used more than 1600 cells, placed on its wings. The aircraft flew from France to England.

1982, Solar Powered Cars
In the year 1982 there was the development of the first solar powered cars in Australia.

1986-1999 Solar Power Plants
Evolution of large scale solar energy plants with advancement being made in each phase. By the year 1999 the largest plant was developed producing more than 20 kilowatts.

1999, Breakthroughs in Solar Cell Efficiency
The most efficient solar cell was developed, with a photovoltaic efficiency of 36 percent.

2008, Subsidy Reduction in Spain
Due to the global financial crisis in the year 2008, the Spanish government reduced subsidies on ongoing solar power production in the country. This had a negative effect on the industry across the world.

2010, Evergreen Solar and Solyndra Fail
Two leading solar companies failed. This was due to lack of market for their high technology produced products

2012, Record Breaking Solar Plants
The past few years have seen enormous investment in utility-scale solar plants, with records for the largest frequently being broken. As of 2012, the history’s largest solar energy plant is the Golmud Solar Park in China, with an installed capacity of 200 megawatts. This is arguably surpassed by India’s Gujarat Solar Park, a collection of solar farms scattered around the Gujarat region, boasting a combined installed capacity of 605 megawatts.

What is the Best Angle For Solar Panels?

Producing electricity with photovoltaics is most efficient when panels are directly facing the sun, however there is no single, global best angle for solar panels to be installed.

Calculating the optimal angle depends on the latitude of the location where they’re being installed.

According to military and government OEM solutions provider Ok Solar, for a house situated at 0-15° latitude, the best angle for solar panels is 15°. For houses situated at 25-30°, add 5° to local latitude, for 30-35° add 10° to local latitude, for 35-40° add 15° to local latitude, and for houses situated at more than 40° add 20° to local latitude [1].

You can use the map below to find your latitude. Once you search for your city, the map will display your latitude.

The best angle for your location will also change between summer and winter, when the sun is higher or lower in the sky in your location.

Once you’ve calculated what is the best angle for your solar panels, you’ve got a few options for how to acheive it.

• You can get static framing made to measure to suit the optimal angle. Going for your optimal winter angle will make your year-round production more consistent, but having a sub-optimal summer angle will mean you’re not using your panels to full capacity in the summer.
• A better option for static panels is to get frames that are manually adjustable, so you can raise the angle during winter and lower it during summer.

• Solar tracker systems are a more expensive but effective option for ensuring your solar panels have the best angle all day long, every day of the year. Solar trackers constantly change the tilt of your panels to face the sun and follow it through the day.

Installing solar on your roof is useful as not only does it take advantage of unused space, you also make use of the roof’s pitch to acheive an optimal angle. Panels can be directly installed to the roof, or spacers can be used to adjust the angle.

For ground mounted panels, installation at the correct angle will yield around a 15% increase against panels installed flat [2].

by Clint Ouma

If you see a solar panel, chances are it’s made of monocrystalline solar cells. Monocrystalline, also commonly known as crystalline silicon or single crystalline silicon, are by far the most widely used solar photovoltaic technology.

This article takes a detailed look at how monocrystalline solar panels work. If you’re looking for a more simple explanation of solar photovoltaics, you may wish to read the article on how solar panels work.

Monocrystalline cells were first developed in 1955 [1]. They conduct and convert the sun’s energy to produce electricity.

When sunlight hits the silicon semiconductor, enough energy is absorbed from the light to knock electrons loose, allowing them to flow freely. Monocrystalline silicon solar cells are designed in such a way that the free electrons can be directed, within the cell’s electric field, in a path or a circuit as electricity which is used to power various appliances [2].

The power (measured in watts) of the cell is determined by the current and the voltage of the cell. The voltage depends on the cell’s internal electric field [2].

Monocrystalline vs Polycrystalline Solar Panels

Crystalline silicon solar cells derive their name from the way they are made. The difference between monocrystalline and polycrystalline solar panels is that monocrystalline cells are cut into thin wafers from a singular continuous crystal that has been grown for this purpose. Polycrystalline cells are made by melting the silicon material and pouring it into a mould [1].

The uniformity of a single crystal cell gives it an even deep blue colour throughout. It also makes it more efficient than the polycrystalline solar modules whose surface is jumbled with various shades of blue [1].

Apart from the crystal growth phase, their is little difference between the construction of mono- and polycrystalline solar cells.

The cells are usually laminated using tempered glass on the front and plastic on the back. These are joined using a clear adhesive and then the module is framed with aluminium. Single crystal modules are usually smaller in size per watt than their polycrystalline counterparts [1].

Why is silicon used in solar cells?

The atomic structure of silicon makes it one of the ideal elements for this kind of solar cell. The silicon atom has 14 electrons and its structure is such that its outermost electron shell contains only four electrons. In order to be stable, this shell needs to have eight electrons.

In its normal state or pure form, each silicon atom attaches itself to four other silicon atoms to form a stable silicon crystal [2].

In the silicon crystal’s pure state, there are very few free electrons available for carrying the electric current. In order to alter their electrical conductivity, other elements are introduced to the silicon as useful impurities in a process known as Doping [2].

Doping of silicon semiconductors for use in solar cells

Doping is the formation of P-Type and N-Type semiconductors by the introduction of foreign atoms into the regular crystal lattice of silicon or germanium in order to change their electrical properties [3].

As mentioned above, electricity is generated when free electrons are directed to carry a current within the cell’s electric field [2].

When the silicon atoms share their electrons, they can attain equilibrium easily because each atom needs four electrons and each can give four electrons.

The elements used in doping however, either have 5 or 3 electrons that they can share which are also known as valence electrons [3].

When elements with five valence electrons are introduced to the silicon crystals, the normal sharing of electrons begins, but the fifth electron remains unattached or unbound [2]. This unbound electron can easily be dislodged from the atomic shell when energy is introduced to the crystal causing it to be negatively charged.

This makes the crystal an N-Type semiconductor where the “N” stands for negative [2].

Some of the elements with 5 valence electrons include phosphorus, antimony and arsenic; phosphorus is the most commonly used element in crystalline solar cells.

On the other hand, when elements with three valence electrons such as boron, aluminium and gallium are introduced, there is a deficiency of electrons and instead, holes are formed [3].

This means that the crystal will carry a positive charge because it needs extra electrons to fill the hole left thus making it a P-Type Semiconductor where the “P” stands for positive. The holes move around seeking to be filled just as the free electrons move around ‘looking’ for holes to fill [2].

The P-Type and N-Type silicon semiconductors are combined to make the solar cell. When in contact, these two semiconductors generate the electric field which is necessary for electricity to flow in the solar cell [2].

The extra or free electrons in the N side are attracted to fill the holes in the P side. Unfortunately, at the point of contact, also called the junction of the two semiconductors, the electrons and holes mix to form a barrier preventing the electrons on the N side from crossing to the P side.

This barrier becomes an electric field separating the two sides when equilibrium is reached and acts as a diode allowing the flow of electrons in one direction, from the P-type semiconductor to the N-type [2].

Electricity generation at cell level

All that is needed for the electricity to be generated is the flow of electrons through a path provided within the electric field. However, we have seen that the flow of electrons has been localized and limited by the electric field which acts as a barrier between the cells. Nevertheless, this flow can be achieved when sunlight hits the solar cell.

The sun’s rays carry their energy in form of photons. Each photon usually has enough energy to dislodge one electron when it hits the solar cell [2].

In freeing one electron, it automatically causes a hole to be freed simultaneously. Due to the barrier’s disposition to allow the flow of electrons to the N-side only, the freed electron – if within the range of the electric field – will be sent to the N-Type semiconductor while the hole is sent to the P-Type.

Since this motion does not restore balance, the electron that was just displaced will seek to return to the P-Side so that neutrality is restored. Since the electron cannot cross back to the P Side from the N-Side via the barrier between the semiconductors, an external current path is built to allow this electron to return to the P – Side.

While the electrons flow through the external current path, we can make use of its energy to power electrical appliances [2].

Crystalline silicon solar cell efficiency

One of the major subjects of research into crystalline silicon solar cells is their efficiency. It’s widely believed that the absolute limit is that 25% of the solar energy that hits a crystalline cell can be converted to electricity [2].

Researchers are hard at work to reach this efficiency with some companies like Sunpower and Sanyo achieving high efficiencies of up to 24% [4].

The wide spectrum of sun light wavelengths is responsible for the loss of about 70% of the energy that hits the solar cell [2].

The light from the sun has different wave lengths which we see as different colours. The different wavelengths also differ in energy content; some have more energy than the solar cell needs to produce electricity while others have less energy.

The crystalline silicon cell needs about 1.1 eV (Electron Volts) of energy to release an electron in the semiconductor; any energy that is more or less than this simply goes through the cell with no effect [2]. This energy used to release the electron is unique for each material and is known as the material’s band gap.

The band gap also determines the voltage of the cell. If the band gap is low, the voltage is also low. Therefore, although using a material that has a low band gap can increase the current of the cell, it lowers the cell’s voltage. Since Power is the product of current and voltage, the power output of the cell cannot be improved in this way. The optimal band gap for a solar cell made from one material has thus been found to be 1.4 eV so as to balance the effect of the current and voltage [2].

The Future of Monocrystalline Silicon Solar Cells

Having been in the market for more than 50 years, silicon solar cells are approaching if not passing their peak potential.

As such, extensive research has gone into improving the efficiency and lowering production costs of these systems.

Now, new technology is hitting the market. The introduction of thin film solar modules, for example, has attracted a lot of attention.

Market forces in countries like the U.S. have made it unprofitable for many companies to continue manufacturing the traditional silicon solar cells with companies like GE opting to shift its resources to manufacture thin film solar modules while it closes down its silicon crystalline solar cell plants [5].

This closure of firms has greatly been caused by the fact that manufacturing the traditional solar panels is a lot cheaper in other countries such as China, which is why some American companies are shifting production to the oriental super power [5].

The main difference between the traditional silicon cells is in the materials used to make them. The modifications that go into silicon for use in solar cells make it very expensive [1].

New construction methods and materials are much cheaper and although the efficiencies of the new technologies are much lower with thin film efficiencies ranging from 4% – 12% [6], there is still a lot of room for improvement in the new systems.

Multi-junction solar modules, which combine up to four different elements in their construction, have even surpassed the maximum efficiency of crystalline silicon modules with Spectrolab achieving 41.9% efficiency in the NREL Lab Test [4] while a commercial subsidiary of Boeing set a practical record of 39.2% [4].

Article References

by Clint Ouma

Concentrating solar power is fundamentally different from the solar photovoltaic (PV) power in that it uses the sun’s heat to generate electricity whereas concentrated solar generally uses a solar-thermal method.

Solar PV cells rely on the sunlight being converted directly to electricity while CSP focus the sunlight using reflectors to generate heat that is used to run a steam engine and drive an electric generator [3]. This is the same way power is generated in a fossil fuel thermal plant – using the sun’s heat instead of heat from burning fossil fuels.

Types of Concentrating Solar Power Systems

There are three main types of CSP system;
1. Parabolic Trough Systems
2. Power Tower Systems
3. Parabolic Dish Systems

Parabolic Trough Systems

Parabolic trough systems are the oldest and thus most common CSP systems in use today with early developments of about 354 MW which were installed between 1984 and 1991 in the Mojave Desert in California [5].

Parabolic Trough systems are designed as solar energy collector fields.

The parabolic troughs are made of reflective material which focuses sunlight onto a focal point – a receiver pipe [5].

The receiver pipe contains fluid which transfers the heat to boil water and turn generator turbines.

This design allows the sun’s heat to be focused to between 30 and 100 times its normal intensity [6].

A collector field is made up of an array of parabolic troughs arranged in parallel along a north-south axis [4].

In order to maximize output, the troughs are setup with sun trackers to move about a north-south axis as the sun spans the sky from east to west [4].

This is necessary because the trough has been designed to direct all the sunlight onto the receiver pipe – therefore the angles at which the sunlight hits the trough need to be the same throughout the day.

A heat transfer fluid (HTF) runs through the receiver pipe. Oil is commonly used at the HTF but molten salt is also used frequently [2].

The main characteristics of these fluids are that they can retain high temperatures without turning into gas.

This hot fluid is channeled through a system of pipes where it heats water and generates steam, which is routed to run a steam powered turbine that drives an electric generator [5].

Some advanced systems have energy storage systems that allow the storage of hot fluid for use after the sun sets while other systems have fossil fuel or natural gas powered backup systems [4].

Concentrated Solar Towers

Solar energy tower systems work on the same principle as the parabolic trough system. Simply put, the sunlight is manipulated to heat the heat transfer fluid which is used to generate steam that runs a steam powered electricity generation power plant.

The main difference between the tower and parabolic trough systems is the way the sun is reflected.

Solar tower systems use an array of mirrors, known as heliostats, which have been programmed to track the sun’s motion [4].

These heliostats focus and concentrate the sunlight on a central tower mounted receiver. Unlike the Parabolic trough which increases the sun’s intensity about 100 times, the tower system causes the sunlight to hit the receiver at about 1,500 times the normal intensity of the sun [6].

In 2009, a 20MW solar tower plant went online in Seville, Spain [7]. According to reports the tower systems will be developed to generate between 50MW and 200MW each in the near future [4].

Parabolic Dish Systems

This system is conventionally smaller than the solar tower and parabolic trough systems. Nevertheless, what it lacks in size, it makes up for in power generation.

The parabolic or solar dish systems are known to focus and concentrate the sun’s intensity such that it is amplified up to 2000 times [6].

This high intensity makes it the most efficient system attaining a sun-to-grid conversion rate of 31.5% [7].

This system is made up of a solar concentrator, which is a dish, and a power conversion unit.

The power conversion unit is made up of a heat engine mounted on a receiver [4].

The Dish is mounted on a two-axis system that is programmed to follow the sun throughout the day because the concentrator has to get the most out of the sun in order to maximize the heat delivered at its focal point where the power conversion unit is located [4].

The receiver, which is part of the power conversion unit and lies between the engine and the dish, is made up of a series of tubes that carry a cooling fluid.

Most systems use either helium or hydrogen as the cooling fluid. The fluid absorbs the heat directed at the power conversion unit by the dish and transfers it in controlled amounts to the heat engine where it is converted to electricity [6].

Stirling or Brayson Cycle engines are the preferred choice of power conversion engines used in these systems [4].

The Future of CSP

It is natural that CSP would be compared to solar PV when assessing the future of the technology because they are both solar powered systems. There are three main factors considered when power utilities are debating on which renewable energy technology to generate electricity from. They are [8]

i. Competitive energy Cost
ii. Ancillary Services
iii. Delivery Upon Demand

Leading researchers argue that CSP is in a position to perform better than solar PV in all the three categories [9] especially since the inexpensive thermal storage offered by CSP systems allow for better delivery of energy upon demand [9].

Nevertheless, the recent drops in PV prices of between 30% and 40% have rocked the boat enough for investors to trust more in PV technology [11].

The bottom line is that the CSP technology still lags far behind PV as far as market penetration is concerned.

As a result, market growth surveys and projections continue to indicate that the technology will take a long time to catch up with solar PV.

CSP system installations are expected to reach about 10.8 GW and PV systems to reach 45.2 GW by 2014 while the two systems reported 0.29 GW and 7.0 GW in 2009 respectively [10].

This shows that the market growth prospects of CSP systems are much faster than PV since CSP systems are expected to increase 37 times while PV will increase about 6.5 times. Other factors such as availability of land for CSP systems may limit the developments, but only time can tell.

Article References

By Jenny Griffin

Energy from the sun is free, and can be used to heat water or to power electrical appliances in domestic residences. Below we’ll walk through the two diy solar power methods – solar hot water and solar photovoltaics (electricity).

DIY Solar Hot Water

Using solar energy for domestic water heating is one of the most cost-effective ways to reduce your power bill and the carbon footprint of a household.

Either evacuated tubes or flat plate collectors can be used for diy solar hot water. A conventional boiler or immersion heater can be used to produce hot water for those occasions when the sun does not oblige, which is often necessary for night-heating or in countries where sun exposure is weak in winter [1].

The type of system chosen depends firstly on whether freezing is likely to occur. In climates where freezing is not a problem, there are three main options:

• A batch heater
• A direct pump system
• Or a thermosiphon system

A batch heater employs a storage tank for collection; a direct pump system moves water from a collector to a storage tank; and a thermosiphon system uses gravity, and no pump.

If temperatures are low enough to cause freezing, then drainback or closed loop systems with heat exchangers and antifreeze will be required.

Drainback systems use distilled water to transfer heat, while closed loop systems circulate antifreeze and use a heat exchanger to transmit the heat to prevent freezing [2].

DIY Solar Electricity

Most people choose to have solar photovoltaic (electricity-producing) panels installed on the roof of their homes as this provides elevation and consequently less chance of the panels being shaded by surrounding buildings and trees.

If the panels are at the same angle as the roof, they are afforded better protection from the wind, and are less likely to be damaged.

There are, however, some limiting factors: the roof must provide sufficient space to accommodate the solar panels, the roof structure needs to be strong enough to support the weight of the solar panels, and the roof must face the sun (face south in the northern hemisphere and north in the southern hemisphere), and it must be unshaded for most of the day.

If solar panels are at a different angle to the roof, planning permission may be required.

Non-roof-mounted solar panels allow for increased flexibility in placement and are suitable for use in circumstances where the roof does not meet the above requirements [3].

While solar panels are expensive to install, once installed they require very little maintenance, and will yield value for many years to come – the resultant savings on electricity bills could quickly exceed the cost of installation and maintenance.

In addition, rebates and tax credits are often available, with a tax credit of 30% of the cost offered in the United States. Households with large electricity bills will experience the greatest financial return on this investment.

Solar panels can also greatly increase the value of a house, with potential buyers seeing the potential electricity saving as a huge incentive.

How to Build Your Own Solar Panel

Having a solar electric system installed by a company is expensive, so many people prefer to buy DIY kits, or to build their own.

For those that are not daunted by technical details, the task of building a DIY solar panel can be completed in a very short time. Solar panels can be easily constructed using parts obtained through Amazon, eBay, or from the local hardware store.

The most expensive component of a solar panel is the solar cells, which are made from crystalline silicon and conducting metals that convert sunlight to electricity.

To save costs, blemished or damaged solar cells in working condition can often be picked up at a much lower price than the cost of cells that are in perfectly new condition.

A total of 36 3’x6’ solar cells will be required for a complete solar panel (other sizes are available and can be used, just make sure you buy cells of uniform sizes and wattage).

The cells should be wired in series by soldering, leaving some space between the cells to allow for expansion when they are heated by the sun.

Normally each cell will generate roughly 0.5 volts, so 36 cells in series will produce around 18 volts, which is sufficient to charge a 12 volt battery.

Other equipment that is necessary to complete the system include: an inverter to convert the DC current of the solar panels to AC current used by household appliances; deep-cycle batteries to store surplus energy; and a charge converter to ensure that batteries are not overcharged, or excessively drained.

Once the solar cells are wired together in series, they are attached to a backing-board and secured in a protective box casing built to house your solar cells.

This must be shallow enough to allow sunlight to reach the cells without being inhibited by the sides.

The front of the protective box casing is covered with a durable clear plexiglass front to protect the unit from the weather.

You’ll need to weatherproof your unit by sealing the joins with silicon and painting the backing board if you’re using plywood.

Australia is one of the world’s best locations for using solar panels to generate electricity – utilizing high sun exposure much of the year. This article looks at the use of solar power in Adelaide, South Australia.

Adelaide is an ideal place to install solar panels as it enjoys some of the longest and most intense sun hours in Australia.

Perched along the southern coastline, the city of 1.2 million people has one of the highest instances of solar panel and solar hot water installations. According to a recent Choice.com.au report, Darwin and Adelaide solar power production is between 10 and 30 per cent higher than Melbourne and Hobart.

Solar Buildings

Adelaide was one of the first official Solar Cities in Australia, a program designed to increase the use of renewable energy in Australia. The Solar Cities saw public spaces such as the bus station and icons in the city’s shopping precinct, Rundle Mall, using solar power. The program is run by the Department of Climate Change and Energy Efficiency, the Australian government, and local businesses.

In November 2013, the South Australian Health and Medical Research Institute was opened, receiving a Gold LEED rating from the US Green Building Council. The building uses a passive cooling system through strategic solar shading, automation to suit the building’s users needs, and natural lighting. It is one of only five Australian buildings to receive a Gold LEED rating.

Adelaide Solar Power Leading The Way

According to the Australian Energy Market Operator, in 2013 there are 170,000 homes with solar panels installed in South Australia, double the national average. Adelaide’s three major universities – Adelaide University, Flinders University, and the University of SA have recently combined forces to focus on new solar technology, including solar battery systems.

First Solar, one of the worlds leading solar power companies, recently sealed a deal with Adelaide company IXL Solar to assemble solar panel systems before shipping them off to be installed.

Solar Power Adelaide References

Sexton, M. Governments urged to back solar research push. http://au.news.yahoo.com/technology/a/19965404/governments-urged-to-back-solar-research-push/ (2013)

Big solar delivers boost to Geelong and Adelaide. http://www.businessspectator.com.au/news/2013/11/21/solar-energy/big-solar-delivers-boost-geelong-and-adelaide (2013)

Fedele, A. LEED Expectations for New Adelaide Research Facility. http://sourceable.net/leed-expectations-for-new-adelaide-research-facility/#sthash.7sZdjWOF.dpuf (2013)

Wang, L. SAHMRI’s Striking Pinecone-Inspired “Living Skin” Uses Passive Solar Design in Australia http://inhabitat.com/sahmris-striking-pinecone-inspired-living-skin-uses-passive-solar-design-in-australia/ (2013)

By Yani Smith

Tax incentives and reduced manufacturing costs have driven solar prices down to an all time low in the US.

This year, a dramatic drop in solar panel prices made it a reality that home owners can finally save money on their power costs while contributing to a healthier future.

Whats more, 2015’s solar price-shakeup has occurred in tandem with tax credits that hit the sweet spot of reliability and accessibility for individual citizens (more on that later).

In turn, it’s been a record breaking year for the number of residential solar installations across the United States.

According to a report by the Solar Energy Industries Association and GTM Research, the United States is moving at lightening pace towards completing it’s one millionth solar installation in 2015 [1]. Finally, it seems, solar has broken the threshold and become a fully fledged, profitable option for Americans.

Historically, solar was simply too expensive for regular households, but that is no longer the case. Largely due to the increase in production and economies of scale, rooftop solar is now more affordable than ever.

According to GTM Research’s Shyam Mehta, there has been a “end-market mix shift toward rooftop applications, and reduced all-in costs for high-efficiency products.” [1]

What’s more, technology such as installation brackets have advanced, meaning installations can be done significantly faster and cheaper.

According to Renewable Energy World’s Solar Outlook 2015[2], “the U.S. industry is enjoying a host of feeders: low PV prices, new emphasis on greenhouse gas reductions, a U.S. President with a pro-green energy agenda, better utility understanding of its grid benefits and a growing desire among consumers to use locally controlled energy.”

Tax Credits on Solar Panels

One such emphasis is the 30% investment tax credit available to residents who install solar panels.

California residents can also take advantage of the California Solar Initiative (CSI) rebate program. The program was developed to create 3,000MW of new solar energy within the next two years. 

Take advantage of tax incentives while you still can however. It’s due to be winding down in 2016.

“That’s likely to encourage people to install solar sooner rather than later,” says Renewable Energy World’s Elisa Wood. [2]

Similar urgency to take advantage of the solar tax credit is being expressed by leaders across the industry.

Tom Leyden, CEO of Solar Grid Storage, expects “a frenzied effort by the industry and buyers to jump on the solar band wagon before the end of the 30 percent ITC”. [2]

Reliable Solar Financing

Solar-friendly financing models have been refined to better suit the needs of customers wanting to install small scale residential solar panels.

Financing options come in all shapes and sizes depending on the home-owners needs.

One stand-out and increasingly common option is where a third-party owns and maintains the system. The panels supply your house with electricity, and any excess is sold back into the grid.

Leasing and lease-to-own options reduce your upfront costs as you pay for the system on a monthly basis.

Conclusion: Now is the Time to Go Solar

2015 is the year of solar energy in the United States. It has become the smart option for clean residential energy at a time of burgeoning energy crisis and destabilizing events such as drought in California.

Cheaper manufacturing prices, a maturing industry, smart tax credits, and dynamic financing models allow more people to invest in their own future through clean energy.

By Yani Smith

If you are interested in learning more about solar in your area, Click Here To Find An Accredited Local Solar Professional.

Article References

[1] http://www.greentechmedia.com/articles/read/The-Most-Important-Trends-in-Solar-in-8-Charts
[2] http://www.renewableenergyworld.com/rea/news/article/2015/01/solar-outlook-2015-still-growing-but-no-longer-energys-young-kid
[3] http://www.solarpowerrocks.com/california/
[4] http://www.sullivansolarpower.com/purchase-agreement
[5] http://www.washingtonpost.com/news/energy-environment/wp/2015/03/17/california-could-power-itself-three-to-five-times-over-with-solar/
[6] http://www.solarcity.com/
[7] http://michaelbluejay.com/electricity/solar.html
[8] http://www.dsireusa.org/

Solar Roof Tiles – Bringing Photovoltaic Technology into Roof Shingles

by Jenny Griffin

The introduction of photovoltaic roof tiles offers an ingenious alternative to bulky photovoltaic panels for harnessing energy from the sun.

Solar energy is typically harnessed through the use of photovoltaic solar panels made of crystalline silicon, which are attached to a roof or other structure.

These panels are positioned facing the sun (south in the northern hemisphere, north in the southern hemisphere) or on a solar tracking system that follows the sun.

Because silicon solar panels are bulky, they can be unsightly, and are also prone to damage in areas that experience strong winds.

Photovoltaic roof tiles are either made from regular crystalline silicone-based materials, or from thin-film solar cells, manufactured from layers of very thin semiconductor materials, such as amorphous silicon, or from other materials such as cadmium telluride, or copper indium gallium diselenide (CIGS).

The latter are thin, flexible, and durable, and ideally suited for use as a roof tile substitute that offers a protective roof cover, while drawing energy from the sun to provide your home with power. [1]

How Photovoltaic Shingles Work

Photovoltaic shingles work on the same principal as regular crystalline solar panels. Photovoltaic literally means ‘light energy’.

The semiconductor photovoltaic cells absorb energy radiated from sunlight, which is then transformed from light (photo) energy into electric (voltaic) current. When energy from sunlight strikes the semiconductor material in the photovoltaic cells, a photon of light energy is absorbed, releasing an electron, which produces an electric current.

The current produced is direct current (DC), but as homes and business run on alternating current (AC), this needs to be converted by an inverter for domestic use. Once the current has been converted to alternating current, it can be connected to the main power board of a building to provide power locally, or it can even be connected to the electricity grid to provide power further afield. [2]

Installing Solar Roof Tiles

A regular solar panel typically consists of 40 photovoltaic cells that are installed in arrays of between 10-20 panels in a typical home system.

The panels can be installed onto an existing roof structure, or placed anywhere on the property to take optimal advantage of available sunlight. Photovoltaic roof tiles on the other hand, form an integral part of the roof structure, replacing regular roof tiles to serve a dual purpose of both repelling water, snow, hail, and wind, while absorbing the energy of the sun as a source of power.

While replacing existing roof tiles with photovoltaic tiles may be rather costly, when constructing a new home this may be quite cost effective in the long term, as it saves on the cost of roof tiles, and offers dramatic savings on energy costs.

Types of Photovoltaic Roof Shingles

Photovoltaic roof shingles are available in silicon or thin-film solar materials.

With energy efficiencies as high as 20.3% attained by silicon photovoltaic cells [3], silicon roof tiles, like silicon solar panels, are more energy efficient than thin-film solar tiles, but they are expensive, and take a long time to install.

Thin-film solar tiles are a recent innovation that are more affordable than silicon roof tiles, as they are cheaper to produce.

They are easy to install, cutting the installation time down by half – to around ten hours, which offers a further cost saving in terms of time and labor.

With ongoing research and development, thin-film photovoltaic roof tiles are catching up in terms of energy efficiency.

A new record of 19.9% efficiency has been attained for CIGS thin-film solar cells by researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory [3].

This improved energy efficiency, together with the affordability and ease of installation, may make thin-film photovoltaic roof tiles the photovoltaic option of choice for solar power installations in the very near future.

Article References

[1] National Renewable Energy Laboratory. Learning About Renewable Energy: Solar Photovoltaic Technology.

[2] ExploringGreenTechnology.com: How Solar Panels Works.

[3] National Renewable Energy Laboratory. Record Makes Thin-Film Solar Cell Competitive with Silicon Efficiency.

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As of 2012, the Montalto di Castro solar park was the largest photovoltaic power station in Italy, producing more than 40,000 MWh of electricity per year.

It was developed and is operated by SunRay Renewable Energy, and its modules produced by SunPower.

The solar park was completed in the winter of 2010, then sold to a consortium of investors.

Montalto di Castro uses sun-tracking technology – changing the angle of the solar panels with the sun for optimal radiation exposure.

The park contains 80,000 modules, with a peak installed capacity of 24 megawatts.

It’s located located around 100km from Rome, in the Lazio Region of Italy.

The construction of the Montalto di Castro solar park took place in 4 stages. It took eight months and approximately 250 workers.

According to the SunPower website, the solar park avoids 22,000 tons of CO2 annually and produces enough solar generated electricity to power 13,000 homes.

Article References

SunPower. Largest Solar Power Plant in Italy Completed. Retrieved from http://us.sunpowercorp.com/about/newsroom/press-releases/?relID=23297

Wikipedia. Solar Power in Italy. Retrieved from http://en.wikipedia.org/wiki/Solar_power_in_Italy

SMA. Solar Park Montalto di Castro. Retrieved from http://www.sma.de/en/products/references/solar-inverters/isolator/solar-park-montalto-di-castro.html

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A solar tracker is a system whereby solar photovoltaic panels  follow the sun throughout the day – retaining the best angle for maximum radiation exposure.

Solar modules are mounted on tracking frames, connected to a solar actuator – which acts like a hydrolic lift or extender.

As the sun moves across the sky, the actuator extends and moves the solar panel in order to keep the optimal angle with the sun.

Working with solar trackers is becoming increasingly popular in both domestic and utility scale systems as it boosts the overall efficiency of photovoltaic installations.

The LINAK Solar Park in Denmark found that by adding trackers to their solar modules, they could get 30-40 percent additional electricity output.

The solar park was a green initiative of the LINAK company, setup next their headquarters. It is expected to generate around 90,000 kilowatt hours per year.

Many large utility solar parks are also using solar tracker systems, such as Italy’s 80,000 module Montalto di Castro.

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