Solar confusion

Do you know the difference between solar thermal and solar photovoltaic panels? Having just written a piece on solar photovoltaics, I’ve realised that many people who oughts to know better simply don’t have a clue. At best they understand that these systems are something to do with renewable energy. This is particularly worrying because on April 1st (and this is not a joke) the Government began paying for electrical energy generated using renewable systems through a Feed-in Tariff or ‘Clean Energy Cashback Scheme’.

To put the record straight, you’ll need solar photovoltaics, or PVs as they’re commonly known, if you want to produce electricity and benefit from the Feed-in Tariff. The only attributes that PV’s and solar thermal systems have in common is that they both use daylight to produce energy and are often found on the roofs of buildings in panel form. Although they can look similar from a distance, the key point to remember about solar thermal panels is that they are a relatively efficient means of heating water and, in the UK, are capable of providing around 50% of a household’s annual hot water requirement.

PVs on the other hand use thin layers of a semi-conducting material, usually silicon, which generates an electric charge when exposed to daylight. The electricity produced by the systems flows to an inverter, a device which converts the electricity from direct current (DC) to alternating current (AC), for use in the home. When the systems are producing more power than is needed, electricity is exported and sold back to the utility company.

Under the new Feed-in Tariff the Government will pay people with PV panels up to 41.3 pence/kilowatt hour for the electricity they generate providing a return on investment of up to 10 per cent in some cases. Homeowners who install a typical 2.5kW solar PV installation could find themselves £1000 better off each year. Across Europe, Feed-in Tariffs have done more than anything else to increase the installation of renewable energy capacity. In Germany alone, which has had Feed-in Tariffs since 2000, 130,000 homes are fitted with PV panels each year.

But don’t despair if you’re keen to use solar energy to heat hot water, the Government is due to introduce a Renewable Heat Incentive in 2011 and this will embrace everything from solar hot water to biomass as well as ground and air source heat pumps.

Image credit: SIG Sustainable Solutions