The disaster at Fukushima has raised public awareness and made the shift to renewable sources of energy more desirable than ever. It is accompanied, too, by a political willingness to rethink and correct the policies followed until now. The question is often posed in public debate as to whether the shift to renewable energies will be too expensive, or whether it indeed poses a threat to Germany’s competitiveness as an industrial location.

Over the last two years, however, studies have suggested that fears of this sort are unfounded. On the contrary, according to an EU study performed by the Fraunhofer Institute for Systems and Innovation Research ISI in Karlsruhe, a shift towards renewable energies will stimulate growth in the job market in the coming decade. By 2020 scientists predict that some 2.8 million people will be employed in Europe’s renewable energy sector, once implementation of EU objectives in this area has taken hold. The negative impact of a shift to alternative energy is far outweighed by the remaining positive net effect of some 400,000 additional jobs in the EU as a whole. What is more, Europe’s GDP is expected to grow by 0.24 % (some 35 billion Euro).

Similar results were reported in a study of Germany contracted by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety BMU, in which ISI scientists participated. One of the study’s findings showed that “the short and long-term effects on the German labor market derived from expansion of renewable energy use, indicate a positive trend. When all negative effects and influences on the economic cycle are taken into account, the number still falls in the range of 120.000 — 140,000 new jobs (2020, optimistic scenario, price path A).”

Presenting the study’s finding at a press conference, Fraunhofer President Prof. Hans-Jörg Bullinger emphasized the Fraunhofer-Gesellschaft’s committed efforts in this field of research: “We are perfectly positioned to develop concepts and solutions for a transition to renewable energy. Within the Fraunhofer Energy Alliance alone there are some 2000 scientists from 16 organizations whose work is focused in this sector. They develop system technologies such as power grids and energy storage systems and research new ways to increase energy efficiency. There are also additional teams of scientists from the Building Innovation and Traffic and Transport Alliances, who also devote a significant part of their work to the question of energy.”

Renewable energy is affordable

“The transition to sustainable energy supplies is one of the greatest challenges of the 21st century,” asserts Prof. Eicke Weber, spokesperson for the Fraunhofer Energy Alliance and Director of the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg. “To keep electricity, heat and transportation prices affordable in the future, we have to use energy more efficiently and devote more research to the development of renewable sources.” Dr. Mario Ragwitz of the ISI, who coordinated the EU study, further emphasizes, “We must sustain investment in renewable energy. And we must be patient.” But it is worth the effort, not only to secure the supply of raw materials and to protect the environment, but also economically from a mid- to long-term perspective, a conclusion also reached in a study by the Renewable Energy Research Association FVEE.

Another study entitled “Vision for a 100 percent renewable energy system,” illustrates how a reliable, affordable and robust energy supply based on renewable sources can be achieved in Germany by the year 2050. “The expansion of renewable energy creates additional costs initially; however, costs should peak in 2015 at a total of about 17 billion Euro. That is only about eight percent of total costs for energy in Germany, and costs will sink again after that. Between 2010 and 2050, overall savings of some 730 billion Euro can be achieved in the electricity and heating sectors alone,” reports Prof. Jürgen Schmid, Director of the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in Kassel, summarizing the results of the study.

Solar energy will become increasingly more competitive

It is also clear that the costs of renewable energy will fall. “We predict, for example, that the price trend for photovoltaic modules (PV) will continue to follow a price-learning curve in the years ahead,” says Eicke Weber. This trend assumes that the price of PV modules, currently between € 1.50 und € 2.00/Wp (net), could fall below € 1.00/Wp as early as 2016, which would put electricity generation costs in Germany in a range between 11 and 14 cents per kilowatt hour. The prerequisites for this reduction in costs are the further development of production, effective utilization of production capacities through corresponding growth in the global PV market, the continual implementation of technological innovations in production, and minimization of production processes and costs.

“These goals present a significant challenge to the PV industry, but they are attainable with advances in technology.” Optimizing the costs of supplying power will necessarily lead to a greater percentage of PV in the power mix, according the ISE. “Photovoltaic energy will not only lower electricity production costs in Germany in the future, while offering the benefits of being both free of emissions and noise pollution, it also makes it possible to decentralize the generation of electricity and decrease grid load. Capacities can also be built up rapidly with minimal impact on nature,” says Weber. The minimum percentage for a sensible PV share in the power mix is 14 percent, but in principle researchers at the ISE find a PV ratio of over 30 percent feasible in the medium term.

High standards for wind power stations

With a share of 6.4 percent, wind power in Germany holds first place in power production from renewable sources. “Wind power is already relatively inexpensive. Depending on the location, generating electricity with wind costs between 3 and 6 cents per kilowatt hour,” says Jürgen Schmid. In a new study by the German Wind Energy Association (BWE), experts from the IWES have shown that, according to geo-data, about 8 percent of the land area in Germany outside of forests and protected areas is available for use in wind energy generation. Using just 2 percent of the area per state would yield 198 gigawatts of installable output. In purely mathematical terms, then, onshore wind power could contribute about 390 terawatt hours to Germany’s annual energy consumption, which currently lies at about 600 terawatt hours.

The study makes clear that the potential of onshore wind power is by far not yet exhausted. “Currently, there are just 28 gigawatts of installed wind power,” confirms Dr. Kurt Rohrig, who led the study and summarized the results. In addition, massive wind farms are to be built offshore, which will generate some 20 to 25 gigawatts, or about 15 percent of Germany’s energy needs by the year 2030, according to targets set by BMU. The first German offshore wind farm, alpha ventus, was completed in 2010 and serves as both a demonstration and research platform. The related BMU research initiative is coordinated by the IWES.

Offshore wind farms present a particularly urgent need for innovation. They have to be designed and constructed to withstand wind, water, salt, UV radiation and waves over their entire life-span of some 20 years. A special offshore test chamber has been developed at the IWES in Bremerhaven that makes it possible for the first time to simultaneously simulate the changing mechanical and climatic stress factors to which the systems are exposed. Components are exposed to salt spray mist, waves, UV light and moisture, while at the same time being bent and stretched. The simulation allows researchers to draw conclusions about the reliability and durability of the systems being tested. In other test facilities for mechanical stress on large-scale rotor blades, static and dynamic tests are performed with millions of load alternations at various amplitudes. The facilities accommodate rotor blades up to 70 meters long. A new facility for blade lengths of up to 90 meters will go into operation on 9 June 2011. “The new site will give us the largest test facilities in Europe for rotor blades used in systems working at outputs of up to around 10 megawatts,” says Prof. Andreas Reuter, Director of the IWES in Bremerhaven.

New, intelligent networks and storage devices

A decentralized energy supply derived from renewable sources requires a different grid structure than those currently available, which are designed for a few central large-scale power plants. In the future, a large number of solar, wind, and biomass power plants will have to be coordinated so that predictions on their yield and load can be reasonably balanced. Gaps in supply arising from irregularities in the availability of sun and wind must be compensated for with quick intermediate energy supplies and control plants.

“We do not need nuclear power as a transitional technology,” agree Institute Directors Eicke Weber und Jürgen Schmid. They believe the rapid build-up of renewable sources witnessed in the last years will more likely be impeded by the lack of flexibility of nuclear power plants. Gas-fired combined heat and power systems in combination with storage units and network expansion are more suitable transitional technologies.

Ultimately, it is about making networks more intelligent with a good deal of technical finesse. Experts refer to a smart grid through which the many power generating systems and consumers communicate and match their requirements between themselves in accordance with the availability of wind or sun power. A good deal of research still needs to be done here. Fraunhofer is working intensively on the development and implementation of new concepts.

Scientists at the IWES, for example, are participating in the new research project “Kombikraftwerk 2″ together with nine other partners in industry and science. The project employs models and field tests to network wind, biogas and solar power systems using modern data and communications technologies, bringing them together to create a virtual unit which functions like a power plant. Researchers hope to demonstrate in detail that complete coverage of our energy needs with renewable energy sources is realistic and that the lights won’t go out even if the wind lies down and sunlight is scarce.

Redox flow batteries, for example, may be well-suited to providing the necessary temporary energy storage. These are large, robust, long-life vanadium flow batteries in which chemical vanadium compounds alternately absorb and discharge electrons across a membrane. Several Fraunhofer institutes are cooperating in the development of these flow batteries. The researchers’ long-term goal is to construct a battery facility with the size of a handball field. It would have a capacity of 20 megawatt hours, sufficient to meet the energy needs of about 2000 homes during a long winter night or a cloudy day. But, they are not quite that far yet. The largest laboratory facilities at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen currently produce several kilowatts of power. Researchers hope to reach megawatt levels in about five years.

Unconventional thinking for a new energy supply

There is a call, too, for innovative ideas that draw on as yet untapped potential. One possibility would be to use the heat storage capacity of buildings in an intelligent network as passive energy storage via electric heat pumps and intelligent energy meters. Researchers at the ISE are currently investigating the potential for remote storage employing tariff-controlled heat pumps. Yet another possibility involves using the batteries of tomorrow’s electric cars as energy storage devices when they are connected to the power grid.

A further unconventional idea is to use any surplus electricity for the electrolysis of water. The hydrogen derived would be used together with carbon dioxide to produce methane in massive volume that can be put to use to store energy in chemical form or be fed into existing natural gas grids. This would make use of today’s existing natural gas infrastructure and its immense capacity to store energy, while significantly reducing our dependence on imported gas.

All efforts towards sustainable energy must naturally be accompanied by reductions in consumption and improved efficiency. How this might look in practice has been demonstrated by the ISE through its participation in the refurbishment of energy systems in a 16-storey apartment building in Weingarten, a district of Freiburg. Primary energy needs for heating, warm water, ventilation, lighting and household electricity were reduced by 40 percent. In the next two years, ISE scientists will record and analyze the building’s energy consumption under real operating conditions. Results of the study, as with the project as a whole, will serve as a model and be taken into account in similar energy system renovation plans.

West Texas would be an ideal place to harness solar energy as West Texas has 75 percent more direct solar radiation than East Texas, and would therefore make a perfect location to build large-scale solar power plants. The solar energy potential in West Texas is so big that the energy from sunshine falling on a single acre of land in West Texas is capable to produce the energy compared to 800 barrels of oil each year.

Texas has already established itself as one of nation’s clean energy leaders through the tremendous development of wind energy sector but solar energy could also be utilized as another clean, renewable energy sector in form of large-scale solar power plants.

But in order for Texas to start further exploring solar energy option some things will have to change. The first step for the development of solar energy sector in Texas should be government subsidies and tax reductions that would make solar energy economically viable option. And it would be also good that electric companies offer homeowners incentives and rebates for installing solar panels.

Today, when there is a global clean energy race going on, having rich renewable resources at your disposal is huge start advantage, and Texas should really do the same thing with the solar energy as the state did with the wind energy.

By using solar energy on larger scale Texas would not only significantly diversify its energy portfolio but this would also mean great environmental benefits. Using more renewable energy means using less fossil fuels, and less fossil fuels means less pollution, and less releasing of harmful carbon emissions. With such an abundance of solar and wind energy Texas should really become nation’s leading renewable energy state.

Physics limits traditional solar cells to a maximum efficiency of 26 percent, because silicon only interacts with a certain part of the light spectrum. Achieving an efficiency of 40.7 percent because they contain an extra layer of concentrators — a thin lens that focuses the sunlight onto the cell — and additional materials that react with more of the spectrum. The Department of Energy has been sponsoring ways to overcome the 40 percent barrier.

Although they are more expensive to make, these “multi-junction” cells could lower the cost of solar power to roughly $3 a watt, including installation costs and other expenses, compared to the $8 a watt cost of traditional solar cells, before government rebates. Ultimately, solar power proponents would like to lower the cost to $1 a watt, not including incentives or rebates.

Lawrence Berkely National Laboratories researchers, partly sponsored by the DoE, said earlier this year that 45 percent efficiency could be achieved with cells made from zinc-manganese-tellurium combined with a few oxygen atoms. The technology has been licensed to RoseStreet Labs in Arizona, but only time will tell if it is economically feasible to make the material into solar cells. Additionally, industry giant Sharp Solar has developed a cell that can achieve 36 percent efficiency using a concentrator and elements in the III and V columns of the periodic table instead of silicon.

Still, that doesn’t mean they’re always the best option. According to Earth2Tech, the “small” wind turbine market is expected to double by 2013. By the way, I put “small” in quotes because were talking small in terms of output (100KW or less), not size. Look at the 100KW turbine in the picture and you’ll see what I’m talking about.

A small wind system might not be as suitable as solar panels for your condo, but it might be better for you condo complex. Likewise, small wind’s not ideal for your house in the burbs, but it might out-compete solar at your warehouse, or your farm, or whatever. Says David Link from Pike Research: “Small wind energy is less expensive than solar on a cost per watt basis which is driving more and more businesses and rural consumers to give it a second look.”

Evacuated Solar Tubes

Evacuated solar tubes absorb the sun’s energy, using it to heat water for solar water heaters. “Evacuated” means that the area between the tubes has all of the air removed and is a vacuum, allowing the most efficient insulation for the inner tube, which contains the liquid to be heated. The pressure proof tubes are made of glass, which has very high insulating values.

In the most common form, the “twin-glass tube”, each tube actually consists of two tubes, one within the other and the heat transfer fluid runs in a countercurrent. An alternative system is a U-tube, where the fluid runs directly through the absorber. The absorber is made of a dark material specialized to collect as much solar energy as possible. A collector attached to the tubes contains a special fluid, which vaporizes at a relatively low temperature. The steam formed then rises to the top of each tube into a heat exchanger and heats up the carrier fluid. The cooled liquid then flows back down, into the pipe, to be heated again. The tubes must be placed at a certain angle for the vaporizing and condensing process to work. The solar circulation system can be attached to the collector in two ways. The first, the “wet” connection, has the heat exchanger going directly into the manifold. The second is the “dry” connection, where the exchanger is connected to the manifold via a substance that conducts the heat from one to the other. The benefit of the dry connection is that the exchange does not necessitate emptying the entire system of its fluid.

Evacuated solar tubes are placed in parallel alignment to form the solar panel, which is mounted at an angle dependent on the latitude of the installation. The panels can be installed with a North – South orientation, giving the most effective absorption on a daily basis, or an East – West orientation, which allows year round flexibility.

Evacuated solar tubes are the most efficient form for heating water with solar power. Traditional flat panels only work at peak efficiency when the sun is directly perpendicular to the panel, so most of the day a flat panel will receive a less efficient angled sun ray. Evacuated Solar tubes are round, so they provide a perpendicular surface to the sun during most hours of sunlight.

An evacuated solar tube system is the most expensive, but it is also the most efficient, producing higher temperature with lower amounts of sunshine. The higher temperatures allow a wider variety of uses than other solar systems, such as steam production and air conditioning.

Why has polymer solar cell technology failed so far?
Mr Chaudhary says that since it is already being used in silicon-based solar cells, the use of textured substrate to increase the working capacity of solar cells is not new. There are indications that by the right combination of substrate texture and the solution-based coating, power generated can be increased. But the technology has failed so far because of two reasons. First, it needs extra processing steps and then it needs coating technologies that are a challenge technically. Attempts were also made to use solar cells in valleys by using various methods to produce light absorbing layers. But the performance of solar cells has been poor at the valleys and ridges because of loss of charge and short circuit.

How polymer solar cell technology works
An assistant professor of electrical and computer engineering at Iowa State University Department of Electrical and Computer Engineering and an associate of the US Department of Energy’s Ames Laboratory, Sumit Chaudhary said that researchers are making polymer cells that have the capabilities of capturing more light within the ridges. This includes the light they absorb from outside and the light that gets reflected from one ridge to another. These solar cells are made up of polymers that are lightweight, easy-to make and flexible. Their functioning is improved by a textured substrate pattern that lets the removal of a thin light absorbing layer. As the light absorbing layer goes through the small ridges, it maintains good electrical transport properties in the cells.

Advantages of polymer solar cell technology

• It uses the sun trapping systems in the most efficient manner.
• The efficiency of solar cells improve by 20 percent.

Power conversion efficiency of the light-trapping cells is 20% more than flat solar cells of polymers. There was also a 100% increase in the light captured at the red/near infrared band edge.

Professor Sumit Chaudhary’s team that worked on polymer solar cells technology
Apart from professor Sumit Chaudhary, the team working on this project included, Kai-Ming Ho, an Iowa State Distinguished Professor of Physics and Astronomy and an Ames Laboratory faculty scientist, Kanwar Singh Nalwa, a graduate student in electrical and computer engineering and a student associate of the Ames Laboratory and Joong-Mok Park, an assistant scientist with the Ames Laboratory.

Sumit and his team are being supported by the Iowa Power Fund, the Ames Laboratory and the Department of Energy’s Office of Basic Energy Sciences.

The substrate and coating technology is being patented by The Iowa State University Research Foundation Inc. Once the technology is patented, it will be licensed to solar cells manufacturers. They can then make the proper and the best use of it.

Using solar power to operate its EVs will yield significant cost savings for Brooklyn Bridge Park — more than $200,000 in gasoline costs, and tens of thousands of dollars in electricity costs, over the 25-year lifetime of the project. More than 530 tons of CO2 would have been emitted during this period had the Park chosen to use traditional service vehicles.

“On behalf of Brooklyn Bridge Park, I thank Beautiful Earth for the gift of this pioneering solar-powered charging station for the park’s fleet of electric vehicles,” said President of Brooklyn Bridge Park, Regina Myer. “Brooklyn Bridge Park is New York’s premiere sustainably-built and operated public park and the charging station furthers our mission to honor the environment and conserve resources. We are thrilled to partner with one of Brooklyn’s most innovative technology companies and to help demonstrate the future of renewable energy.”

“There are ambitious emissions reductions goals in PlaNYC, our long-term vision for a greener, greater New York,” said David Bragdon, Director of the Mayor Bloomberg’s Office of Long-Term Planning and Sustainability. “The Beautiful Earth charging station at Brooklyn Bridge Park, and other steps we have taken to green our fleet of vehicles, will help us meet our goal and set an example for the thousands of visitors that will enter the park and see the charging station.”

Constructed with two upcycled, decommissioned steel shipping containers stacked on top of each other, BE’s charging station is off-grid, entirely powered by 24 photovoltaic panels on the roof, which catch the sun’s rays throughout the day and store them as electricity in battery packs for 24/7, on-demand use. With production of 5.6 kilowatts, the station also stores enough energy to power a small home and can charge five electric service vehicles and a full-size electric car as they come and go.

“We are honored to contribute to the sustainability of this 21st century park, one in which an underused stretch of waterfront has been majestically transformed and opened to the public in an environmentally-sensitive way,” said Beautiful Earth Group President and CEO, Lex Heslin. “We look forward to a long, fruitful and emissions-free collaboration.”

BE originally operated its solar-powered EV charging station on an industrial lot in Red Hook before donating it to Brooklyn Bridge Park. To build the station, BE purchased photovoltaic panels made at a Sharp Electronics plant in Tennessee; a racking system from Unirac in New Mexico; recycled containers from a local New York vendor; batteries, which are 97 percent recyclable, from the Trojan Battery Company in Georgia; inverters from OutBack Power Systems in Washington; and the solar array’s frame from U.S. Fence Systems in Brooklyn.

An additional benefit of the charging station is that it is modular — it can be deconstructed, moved and reassembled in less than a day — and it serves as a model for other parks and small businesses looking to use clean energy for their vehicles. The charging station is scheduled to become part of a larger New York Center for Sustainable Energy that will be built and unveiled in the Park this spring.

BE supports the use of electric vehicles as a crucial step toward long-term sustainability in transportation and as an innovative solution that will contribute to New York’s PlaNYC initiative, which seeks a 30 percent reduction in the City’s carbon emissions by 2030.

BE broke ground in December 2010 on two 19 MW photovoltaic (PV) electricity generating plants in Southern California. With a total project cost of approximately $170 million, BE’s Del Sur I and II projects located in Lancaster, CA will supply electricity to over 8,000 homes in the area. BE is also investing extensively in EV charging stations which will use its clean, green electricity.

Wadebridge Renewable Energy Network (Wren) wants to explore ways of introducing hundreds of solar panels to the roofs of homes and businesses.

Wren says that the scheme could also generate £450,000 a year for the town.

The money would come from a feed-in tariff which offers a premium price for renewable energy.

‘Financial benefits’

A number of developers and landowners have shown interest in setting up solar energy farms in Cornwall to take advantage of the feed-in tariff.

Stephen Frankel, of Wren, said: “We’ve some of the best sun and wind resources in the country, so we want to harness them for the good of the people of Wadebridge and neighbouring parishes.

“In other renewable energy projects most of the financial benefits go out of Cornwall, and mostly go out of the country.

“Wren will make sure that these stay here in Wadebridge to bring jobs and other benefits to all sections of the community.”

The project, which has the support of local MP Dan Rogerson, will be launched on 22 January in Wadebridge Town Hall.

I would have thought that, irrespective of Middle Eastern problems, renewable energy sources should be taken seriously, individuals, organisations and governments should champion and accept a good policy for manufacturing now, given that oil supplies are indeed finite, and seize the day and invest heavily in becoming world leaders in innovative and ever more efficient alternatives to oil.

Competition for oil and gas in the Arctic regions are now going to increase, especially since last year, Scottish oil producer Cairn Energy confirmed it had found oil off Greenland and one of Nato’s senior commanders warned the race for resources will lead to conflict. Business as usual until every drop of oil is extracted and burnt will cause resource wars and planetary fever (global heating) and massive loss of bio diversity.

America is urgently building up its military readiness in the Arctic where melting summer sea ice is setting up a new global struggle for resources.

Reducing dependence on oil

The low lying fruit has been picked. Deep water drilling and the readiness to exploit sensitive regions such as the arctic has now demonstrated the real predicament our modern civilisation is in, with our unhealthy dependence on increasingly unstable geographic supplies.

Governments around the world including our coalition government are looking at ways to reduce dependence on oil, so because the UK’s demand is 47% from domestic energy, it now makes sense to find alternative ways to power and heat our homes.

Recent changes in the way governments look at renewable energy around the world have spawned new incentive schemes for domestic solar panels. Generating your own heat/power using improved and government approved solar technologies such as evacuated tubes and pv solar panels are now available using Feed In Tariffs and the Renewable Heat Incentive scheme.

Feed In Tariffs for pv solar electric panels

The majority of European countries now have feed in tariffs such as Germany, France, Italy, Spain, Portugal, Poland, Czech Republic, Switzerland, Netherlands to name only a few.

Feed in tariffs are a way of promoting greener PV solar panels technology. The UK government put through legislation to adopt feed in tariffs in April 2010 in the UK. For example a home owner looking to generate electricity using PV solar under 4 kW (retro fit) will receive a 41.3 per Kwh unit produced giving great payback and long term reduction in energy bought in the home.

The feed in tariff rates will be paid for each unit of electricity generated even if you use it in yourself, in addition any excess power can be exported to the National Grid and you will receive an extra 3p/kWh.
For example: 2.52kWp solar PV panel system produces 2100kWh per year using half of the electricity the system produces in the home and exporting half of the electricity to the National Grid would earn and save:

Earn ((Half the electricity generated 2100/2 kWh x £0.413) + (Half the electricity generated 2100/2 kWh x £0.443) +
Save (Save buying half the electricity generated 2100/2 kWh x £0.13/kWh) = £1,035 per year!

This is a great return of 7.96% and better than keeping the upfront expenditure in the bank.

RHI – Renewable Heat Incentive for solar heating panels

36% of the UK’s overall energy use is used for heating, so the new RHI scheme (Renewable Heat Incentive) is designed to come in 2 phases, with phase 1 being more than a quarter of the first year’s budget, around £15 million, is to be guaranteed up to 25,000 household installations focusing on people living off the gas grid, who typically spend more on their heating with coal, oil and generally higher carbon content.

The highest RHI tariffs for this scheme will be paid to solar heating panels installations with 8.5p per kWh generated. Solar heating was by far the most popular micro generation technology under previous subsidy schemes. It works very well in the UK climate and can supplies between 40 and 50% of a home’s hot water needs, so it is good that it receives the most financial support.

A technology called a heat meter will be installed at the point of generation and where appropriate, at the point of usage in order to claim solar RHI payments. The RHI tariffs will be paid for a guaranteed 20 years for solar panel technologies installed since July 15, 2009 with payments for each kW of heat produced. The levels of RHI support available to new entrants as time goes on may decrease, so it is best to be an early participant than a later one.

The RHI phase 1 home owners will then provide feedback on how the scheme is working to help design the phase 2 of the scheme.

Both the RHI and Feed in tariff incentive schemes are designed to bring about a larger increase in the amount of locally produced green energy, as a contribution to the energy mix from low carbon technologies.

The devices have been fitted to 2,257 homes so far during August, up from 1,700 in July and 1,400 in June.

More than 6,688 homes have had solar panels fitted since April, when the government’s scheme to reward people who generate their own energy altered.

The feed-in tariff system now enables homeowners to receive 41.3p for every unit of energy they generate.

This is regardless of whether they use the energy or sell it back to the National Grid.

After the panels are installed, the tariff is paid for 25 years and increased in line with inflation.

This replaces the previous system, under which people could obtain grants to help cover the cost of installing the green technology.

According to the Energy Saving Trust, solar panels usually cost between £6,000 and £12,000 to buy and install, depending on their size.

The panels most commonly installed by homeowners, consisting of eight panels able to generate up to 2.5kW, cost between £10,000 and £12,000.

The Trust calculates such panels could generate about £700 a year from the feed-in tariff, as well as saving homeowners about £100 a year on energy bills.

In addition, people could make about £25 to £30 through selling unused energy back to the National Grid.