Photo Voltaic Power

Solar photovoltaic (PV) uses energy from the sun to create electricity to run appliances and lighting. PV requires only daylight - not direct sunlight - to generate electricity.

How it works

Photovoltaic systems use cells to convert solar radiation into electricity. The PV cell consists of one or two layers of a semi conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers, causing electricity to flow.

The greater the intensity of the light, the greater the flow of electricity...

PV systems generate no greenhouse gases, saving approximately 455kg of carbon dioxide emissions per year - adding up to about 11 tonnes over a system's lifetime - for each kilowatt peak (kWp - PV cells are referred to in terms of the amount of energy they generate in full sun light).

PV arrays now come in a variety of shapes and colours, ranging from grey 'solar tiles' that look like roof tiles, to panels and transparent cells that you can use on conservatories and glass to provide shading as well as generating electricity. As well as enabling you to generate free electricity they can provide an interesting alternative to conventional roof tiles!

How do you calculate the income generated for PV?

The feed-in tariff (FIT) will provide all generators of renewable energy with a good rate of income from their generated power, making renewable energy systems significantly more economic. The rate of income will be determined by the size of the system. A system of less than 4kwp will be paid 41.3p per unit between 4 -10kw the rate is 36.1p per unit.

Until Smart meters are introduced your electricity provider will assume you use 50% within the home and sell the remaining 50% back to them. You have the option to have a meter installed by your supplier should you wish to do so.

Most suppliers are working on the following assumptions-

1. You will be paid 36.1p for every unit you generate regardless of whether you use it in the home or not.

2. You will be paid 3p per unit for 50% of the kwh generated as it will be assumed you sell this back to your supplier

3. You will save 10p per unit for 50% of the kwh generated, as you will not have to purchase this.

4. The panels are approx 1.39sqm each and weigh 17 kg per panel.

Al East Green Energy supplied PV panel’s come with a guarantee of power output and a miniumum of 20-year performance guarantee.

Solar PV and your home

You can use PV systems for a building with a roof or wall that faces within 90 degrees of south, as long as no other buildings or large trees overshadow it. If the roof surface is in shadow for parts of the day, the output of the system decreases.

Solar PV installations should always be carried out by a trained and experienced installer.

Cost and maintenance

Prices for PV systems vary, depending on the size of the system to be installed, type of PV cell used and the nature of the actual building on which the PV is mounted. The size of the system is dictated by the amount of electricity required.

For the average domestic system, costs can be around £5,000- £8,000 per kWp installed, with most domestic systems usually between 1.5 and 3 kWp. Solar tiles cost more than conventional panels, and panels that are integrated into a roof are more expensive than those that sit on top.

If you intend to have major roof repairs carried out it may be worth exploring PV tiles as they can offset the cost of roof tiles.

Grid connected systems require very little maintenance, generally limited to ensuring that the panels are kept relatively clean and that shade from trees has not become a problem. The wiring and components of the system should however be checked regularly by a qualified technician.

Stand-alone systems, i.e. those not connected to the grid, need maintenance on other system components, such as batteries.

Planning considerations