Solar (PV) photovoltaic grid connected panels

Photovoltaic panels operate by converting solar radiation into electricity. The rated output of a PV module is the power generated in 'peak sunshine conditions' which is approximately the solar radiation found in the UK at mid-day in June on a cloudless day. The measurement of daily insolation is numerically equivalent to 'peak sun hours'. The daily energy supplied by a PV module can be estimated from the equation:

Actual output energy kWh per day= PV Module Rated Power (kW) x daily insolation

The length and intensity of the sunlight reduces with distance from the equator and with time of year.

Insolation (yearly average in KWh/m2)

Edinburgh	825
London	953
Plymouth	1172

Seasonal variation (daily average average in KWh/m2)

Plymouth - June	5.70
Plymouth - December	0.95

A typical small system such as a 2kW array of panels ( e.g. 25 x 80W panel ) sited at an ideal location in Plymouth will produce on average approximately 11.4 kWh per day in June and 1.9 kWh per day in December. (1kWh is 1 unit of electricity) On average each year Thus calaculation neglects some losses and gains but is a good guide to expected output.

Connection to the electricity grid is very similar to the technique adopted for wind energy generation.

Essential requirements

a survey - presence of obstructions such as trees etc.
in most casesplanning permission is not required
permission, when necessary, from the mains electricity supplier