Solar PV (photovoltaic)

Our city isn’t exactly famous for its sunny climate and on overcast, rainy days the idea of Londoners generating electricity from the sun seems pretty far-fetched.

But solar power in London is very much a reality. Solar PV (photovoltaic) uses energy from the sun to create electricity, but it only needs daylight, not direct sunlight, to work so it can still generate some power on a cloudy day.

To install a PV system, you need 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 panels’ surface would be in shadow for parts of the day, the output of the system would decrease.

You can mount PV panels on top of existing roof tiles or replace those tiles with solar tiles. Installing a PV system is not cheap; the exact costs vary according to the size of the system and the type of cells you go for.

The energy and carbon savings depend on how much power you use and at what rate you can sell any unused electricity for. A household with an average sized system, using over half the electricity generated and selling the rest back at a normal rate would save 1.1 tonnes of CO2 and around £170 a year from their bill.

Before you rush off and buy, remember you need to make sure that your roof is strong enough to support the panels and to obtain planning permission if necessary.

Energy Saving Trust: Solar electricity