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1. What is solar photovoltaic (PV)?
Photovoltaic means electricity from light.
A solar PV system uses the natural energy from daylight in the form of solar radiation to generate electricity. This is different technology to solar thermal systems used for heating and hot water.
2. Why should I install a PV system?
By installing a solar PV system you will be generating your own clean green electricity from the free energy of the sun. This will not only reduce your electricity bills but since energy use associated with buildings accounts for around 50% of the CO2 emissions, installing a PV system will also help reduce greenhouse gases.
3. What is a PV system made of?
Solar PV systems are most commonly made from silicon, the second most abundant element in the planet crust, usually in crystalline form. The modules (sometimes referred to as a “panel”) are made from PV cells usually behind glass that are linked together in series like batteries in a torch to generate power output in the form of direct current (DC). A number PV modules can be connected together to give the desired electrical output.
4. How does it work?
A charge is placed across the cell and as the energy from the sun hits the silicon, an electron is released from the atom. Due to the charge across the cell, this electron then flows towards the positive layer. Once you have an electron flow, a current is generated. This direct current is converted by an inverter in the system to an alternating current (AC) at the same level as the national grid.
5. Will it still work on a cloudy day?
As the electricity generation is dependant on light intensity and not direct sunlight it will work in cloudy conditions but the greater the intensity of the light the greater the flow of electricity. Hence you generate more on sunnier days but the system will still produce electricity on cloudy days.
6. How much will it cost?
There is initial capital outlay to install your system which can be subsidised by a grant under the low carbon buildings programme. Once installed, since daylight is free, the system generates free electricity that requires very little maintenance with no moving parts.
7. Will it produce greenhouse gases?
PV systems generate electricity without producing emissions of greenhouse or any other gases. Based on the current electricity mix, every kWh of electricity delivered to your premises from the national grid will have produced 0.43 grammes of CO2. At 800kWh per kWp this will save approximately 344g of CO2 emissions every year.
8. Where can I install a PV system?
A PV system should not be installed in shade such as from other buildings or large trees since this will decrease the output from the system. However, although generally installed on a roof, they can be installed on any surface such as facades, sunshades, garages or ground mounted. They are normally installed in locations that receive sunshine through most of the day i.e. from East through South to West. However, maximum output will be facing due south and between 30-40 degrees from horizontal.
9. Do I need planning permission?
Some authorities require planning permission especially for listed buildings or within a conservation area. Although planning permission for solar PV is not generally required, Sharp recommends that customers should always check with their local authority before having a system installed.
10. How much will a system cost?
There are a number of factors that contribute to the cost of a system including the size of the system, module type, component parts, whether new build or retrofit, accessibility such as scaffolding requirements and labour costs.