Solar Panels (PV)

Generate cheap, green electricity from sunlight

Solar panel electricity systems, are also known as solar photovoltaics (PV). They work by capturing the energy of the sun and converting this into electrical energy which can be used to power the property. It is not necessary for these panels to have bright sunlight, as they work on daylight rather than sunlight. They will not however work at night and not as well in winter as in summer. They can however face any direction except North. They will work if, North facing, just not very well. They can be East/West facing. In fact you can get more power from an East/West array than from a purely South facing one. The reason for this is that presuming each side of the roof is the same size, you can get more panels on an East/West array than on a purely South facing one. The power produced from each panel will be less, but because there are more of them, the result is more power.

Most domestic households install less than 4 kW of solar panels. This will not be enough to eliminate all your electricity bills. However it will reduce them dramatically and you will get paid Feed in Tariff payments for ALL the electricity that you produce including all the power you use in your own home. You will also get a small payment from the electricity company for the power that they presume you have sent to them. This is called a deemed payment and will be equal to half of your total generation. You will also have the benefit of knowing that you have reduced your carbon footprint by approximately one ton per year.

For farmers and non-domestic installations, the planning legislation has recently changed. Planning permission is usually not required for a single installation of Solar PV on non-domestic buildings. This means that farmers and businesses can cover as much of their roof as possible and use the power to eliminate all of their electricity bills. It is now even possible to store all of this power for later use when the sun is not shining.

If you are building a new barn, house or extension, then you will have to put on a roof so why not put solar panels on top of the roof and make money from your roof?

Costs, savings

For non-domestic installations such as factory or barn roofs, the cost can be less than £1 per watt. This means that a 50 kW installation could cost less than £50,000. This could give a pay back in as little as 5 years. The average domestic solar PV system is 3.5 to 4kWp and should cost approximately £7,000 (including VAT at 5%), this should include fitting etc. However each installation is different and so prices may vary. (prices correct at time of writing 2013). Costs are reducing all the time, but the amount of money that can be earned from feed in tariffs also reduces with time, so waiting for prices to come down, might not be the best idea.

Maintenance

Solar PV panels need very little maintenance. You do need to make sure that they are not covered with leaves etc and that trees are not casting shadows on the panels. Most panels keep themselves clean by the action of the rain. Your installer will give you details of any maintenance that will be needed.
The panels should last 25 years. The inverter will probably need replacing before this time.

Micro Inverters and Power Optimisers.

Because most systems connect the panels together in what are called ‘strings’. If there is dirty or even a pigeon on one of the panels, it will affect the performance of all the panels in that string. This can be avoided by using power optimisers or micro inverters. This does increase the cost of the install, but the cost of the inverter is reduced as all the inverting has already been done on the roof. It also, more than pays for itself in the increased production of the system. A further consideration is in areas that might have a safety consideration. In a normal install, there can be a very high power supply on the roof and if there was a fire or if people had to go on the roof, there could be a safety issue. For that reason, for factory and school installations it would be strongly advisable to install micro inverters.