Does PV really work in the UK?
Yes. The PV modules only require daylight to work, and so will generate energy on cloudy and even rainy days. Temperature is also a factor when determining how much electricity a pv system will generate. The efficiency of a PV module decreases by a fraction for every degree the temperature is above 25 degrees Celsius. Therefore, a clear cold day is perfect, because PV modules operate better at cooler temperatures. The UK has similar irradiance levels to Germany where PV has proved extremely popular given their tariff structure, which is now also available within the UK under the Feed in Tariff.
What maintenance and cleaning do the PV systems need?
A Solar PV systems is silent in operation, has no moving parts and requires minimal maintenance. Most of the time the rain will keep the modules clean. However, a build up of dirt can effect system performance. The degree of soiling will depend on the location but usually dust accumulation and self-cleaning reach a steady state after a few weeks if the array tilt is at least 15 degrees. In extreme cases, dust may cause a power reduction of about 10%. The design of the system should aim to minimise uneven soiling. The modules can be cleaned once a year if desired with either a hose or, if possible, soapy water and a non-abrasive cloth.
What size PV system do I need?
There is no simple answer to this question. It will depend on how much you want to invest, how much of your electricity you want to generate via PV, and how much south-facing, un-shaded roof space you have. It is not essential to provide ALL of your home’s electricity via solar PV (since you will still be connected to the national grid). If your PV system supplies half of your electricity, it will still make a serious reduction to your carbon footprint!
How much energy do I need?
According to the Energy Saving Trust, the average three-bedroom house consumes 3,300 units of electricity (kWh) a year (cooking and heating using non electric supply). However, Rexel Renewable Energy always recommends that you look at your last few bills or call your electricity supplier to find out how many units you consume.
What if I produce more energy than I need?
Whenever your panels are producing more electricity than your home is using, it will flow back into the grid for other homes to use. As long as you have an meter that measures the amount of electricity exported, you are eligible to receive a credit for this electricity. This will lower your electricity bills and ensure none of your green electricity will be wasted.
Does the system need batteries?
No. PV systems are connected to the national grid. In the night, when the cells are not generating energy, electricity is bought from the utility company in the normal way. Any excess electricity generated during the day – for example, when you are at work – is sold back to the utility company.
What happens if there is a power cut?
If there is a power cut, your system is automatically switched off. This is a safety measure designed to stop electricity leaking on to the national grid and to protect individuals who may be working to restore the power supply.
Which electricity supplier should I use?
Due to the Feed-in Tariff, all electricity retailers will be obliged to offer the same generation and export credits for microgeneration systems to their customers so you may choose whichever electricity retailer you prefer.
Can I sell the electricity I make?
Yes. On top of the generation tariff you will receive for every unit you generate, the Government’s consultation paper proposes that you are paid 4.5p per kWh for every unit exported back into the electricity grid.
How soon will a PV system pay back the cost of installation?
We estimates that a system installed during the Feed-in Tariff Scheme will be paid back in eleven years. However, in addition, you will carry on receiving a tariff or cashback for a further fourteen years and you will benefit from free electricity for years to come after that.
What is the cost of a solar PV system?
The cost of installation is dependent on a detailed survey and will vary according to how easy or difficult it is to access the roof space and the type and size of the PV system chosen.
A Solar PV installation adds as little as 4% to the build cost of an average new three- bedroom home, but this can be added to its final value when sold. It also helps ‘future proof’ a home against rising fuel prices making properties doubly attractive to price- conscious house buyers. As fuel prices continue to rise, energy-efficient renewably powered homes will continue to sell at a premium.
What grants are available?
Government grants are available to help cover the cost of a PV installation for both domestic and public purposes.
How long will it take to install my system?
PV systems can be installed and ready to produce electricity in 2-8 weeks from the time the design has been agreed. The actual installation will take approximately one day per kilowatt installed depending upon your building type.
Doesn’t the glazed front reflect light away from solar PV modules?
No. Solar PV modules constructed with a glass front have two characteristics that reduce light reflection. In order to optimize electrical yield, the glass is treated with an anti-reflective coating which greatly increases the transmittance through the glass, maximising the amount of light reaching the solar cells. Secondly, the outer face of the glass has a slight granular texture. The result is a matt-like finish – rather than mirrored. Again, this is actually intended to maximize yield. These two characteristics greatly reduce reflection from the glazed front face of solar PV modules when compared with conventional glazing.
Are there disadvantages to using solar PV energy?
Solar energy technologies often have a higher investment cost. This means that a person is likely to pay more money initially to purchase and install a solar PV system. Still, in nearly all cases, the high initial cost is recovered through substantial fuel savings within the life of the product (40+ years). This time is significantly reduced by any government incentives in place such as grants and Feed-in Tariffs.
Can I use PV to power my business?
PV systems can be blended into virtually every conceivable structure for commercial buildings. You will find PV being used outdoors for security lighting as well as in structures that serve as covers for car parks and bus shelters, generating power at the same time. PV systems are also used to offset and operate all kinds of electrical systems, including lights, cooling systems, and appliances.
Today’s modules can be built into glass skylights and walls. Some resemble traditional roof shingles. Architects can use building-integrated PV (BIPV) to design buildings that are environmentally-responsive, aesthetically-pleasing, and produce their own power. BIPV provides a dual-use building material, reduces PV system costs by using the building as the mounting or support structure, and reduces utility bills through on-site power production.
How can PV glass laminates and flexible thin film PV be used architecturally?
PV glass laminates are attractive and well suited to facades and transparent roof tops. They can be fitted to standard curtain walling structures and are suitable for any application where glass is used, as long as there is a reasonable level of light present.
What’s the difference between PV and other solar technologies?
There are four main types of solar energy technologies:
1. Photovoltaic (PV) systems, which convert sunlight directly to electricity by means of PV cells made of semiconductor materials.
2. Concentrating solar power (CSP) systems, which concentrate the sun’s energy using reflective devices such as troughs or mirror panels to produce heat that is then used to generate electricity.
3. Solar water heating systems, which contain a solar collector that faces the sun and either heats water directly or heats a working fluid that, in turn, is used to heat water.
4. Transpired solar collectors, or solar walls, which use solar energy to preheat ventilation air for a building.