The power of solar energy

Sharp’s factory near Wrexham for producing solar photo-voltaic panels has a production capability of 110 MW a year.
Tucked away in the north-east corner of Wales is a factory producing photo-voltaic solar panels and being installed in a rapidly growing number of substantial projects in the UK.Nuclear power ... only nicer — that is how Daniel Wan of Sharp UK’s solar division describes solar energy. The nuclear processes that produce the energy that eventually reaches the Earth are, of course, fusion, whereas nuclear reactors on the Earth exploit fission. However, the Sun is a comforting 150 million kilometres away. Such vast quantities of energy from the Sun fall on the Earth that just an hour’s worth could power its population for a year, says Daniel Wan. Another way of looking at it, he says, is that less than 1600 km2 of solar photo-voltaic modules in the Sahara Desert could generate the world’s electricity requirements. Immense One more way of indicating the immense amount of solar energy that falls on the Earth is that just 0.01% of it could meet the total energy needs of the world. Sharp is the world’s largest producer of photo-voltaic panels for converting solar energy to electricity. The company claims a 26% share of the 2005 global production of 1727 MW — nearly three times greater than the next nearest competitor. The company first developed solar cells in 1959, with series production starting over 40 years ago in 1963. One of the five Sharp solar factories in the world is at Llay in north-east Wales. The output capability of this factory in February 2006 was 110 MW per year, or about 2400 panels per 24 hours or more than double the 50 MW capability at March 2005. One important aspect of solar PV panels as a method of exploiting renewable energy is that they have no moving parts. There are thus no significant maintenance issues, and solar panels have a long life — as evidenced by space and earth-bound projects. Daniel Wan reminds us that the generation of electricity from solar energy is dependent on light intensity. It does not require direct sunlight, so electricity can be produced even on overcast days. He stresses, ‘Germany, with a similar climate to the UK, is one of the world’s largest solar markets.’ There are several types of PV cell. The most efficient is the monocrystalline, with a conversion efficiency of up to 20%. While the technology is well proven, the manufacturing process is complicated and, therefore, expensive. While less efficient, polycrystalline panels, with a conversion efficiency of 8 to 12% are cheaper to produce than monocrystalline. They are also a proven technology and generally considered to have a more attractive appearance. Even cheaper to produce is amorphous silicon thin film, but its efficiency is only 4 to 6%. This technology is suitable for integrating into buildings, such as substituting for roof tiles and performs well in low light conditions. However, it is still an immature technology. Solar PV technology continues to develop, and one of the newest is an amorphous silicon and crystalline structure. It has only 1% of the silicon requirement of standard thin film and is 1.5 times more efficient. Integrating such solar PV technology into a building’s electrical system requires an inverter to convert direct current to alternating current that is synchronised with the mains supply and a means of exporting surplus electricity to the National Grid. An extra electricity meter keeps track of how much electricity is exported. In domestic applications, PV electricity can make a major contribution to annual usage. Daniel Wan explains that a typical domestic installation with an electrical output of 2 kW would generate about 1700 kWh over the course of a year — about 60% of demand and represent a reduction in carbon-dioxide emissions of 700 kg. Domestic market To stimulate the domestic market, Sharp Electronics has teamed up with electrical retailer Currys to offer a range of solar energy solutions. Solar panels will initially be on sale in three Currys stores, and information will also be available online. The panels will have a performance warranty of 25 years and require minimum maintenance by the customer. Sharp also has a wealth of large commercial installations in the UK. The largest, indeed the largest in Europe, is the recent recladding of the service tower of CIS in Manchester with over 7400 PV modules. The 364 m-high tower is clad with dark-blue panels with an output of 180 MWh a year. This £5.5 million project was supported by a grant of £885 000 from the North West Development Agency and a grant of £175 000 from the Department of Trade & Industry.
The service tower of the CIS tower in Manchester was recently reclad with solar PV panels with an output of 180 000 kWh a year.
The PV panels on the CIS tower were installed as part of the refurbishment of this 40-year-old structure and replaced the small mosaic tiles that previously clad the tower. Another pioneering project in Manchester is the new sixth-form centre of Manchester College of Arts & Technology (MANCAT). The original Grade 2 listed Victorian building has been restored and a futuristic extension added to create a sixth-form college, library and exhibition hall.
44 MWh of electricity is being generated by solar PV panels on the façade and roof of the new sixth-form centre of Manchester College of Arts & Technology.  
This new 2-story building is clad on its front aspect with polycrystalline modules. There is also a roof-mounted system over the pitched roof of the exhibition hall and an array on the roof of the library. 480 polycrystalline panels with an output of 80 W each are installed on the front of the building. Each panel has a black backing and black frame to create a striking monolithic façade. The rest of the installation comprises over 250 modules of 165 W each. The MANCAT installation has a maximum electrical output of 78 kW and will generate nearly 44 MWh of electricity a year. An example of a large-scale residential installation is the Priors Estate of Peabody Trust in London. Peabody Trust is a pioneer in affordable housing, and the Priors Estate has 200 residents.
Solar PV panels retrofitted to the roof of three residential blocks of Peabody Trust’s Priors Estate in London have a total output of 158 kW.  
900 monocrystalline silicon modules with a total output of 158 kW are retrofitted on the roofs of three buildings. They have a total area of 1170 m2 and generate 130 kWh of electricity a year, saving 56 t of carbon-dioxide emissions per year. The life expectancy of these panels is in excess of 50 years, and they are recyclable at the end of their life. Drivers Andrew Lee, general manager of Sharp’s solar division in the UK, sees the potential for growth becoming even greater between now and 2010. Until now, the major driver has been the Major Demonstration Programme, which is being succeeded by the Low Carbon Buildings Programme. One of the important drivers in the future will be the construction programme for the 2012 Olympic Games in London. The latest Building Regulations are already having an effect, as are Renewable Obligation Certificates and planning regulations such as the 10% renewable-energy requirement of the London Borough of Merton. Would it be too much of a pun to suggest that the future is bright for solar energy in the UK?
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