kWp
kilowatt peak
The power of a solar panel system measured under standard conditions: how many kW the panels would give in strong sunshine at the right temperature.
The kWp measures the size of a solar panel system, not the energy it produces. It is the power the panels give under standard test conditions, with sunlight of 1,000 watts per square metre and 25 degrees. On a roof those conditions are rare, so a 3 kWp system seldom actually delivers 3 kW.
With today's panels, of about 430 watts, 1 kWp takes about 5 square metres of roof, a little more if the panels sit in spaced rows on a flat roof.
What matters for the money is the energy over a year: in Italy 1 kWp facing the right way produces from about 1,100 kWh a year in the north to over 1,600 in Sicily. On a slope facing east or west about a fifth is lost. In the report the estimate is for 1 kWp at the address and then for the kWp that actually fit on the good slopes of the roof.
Official source: re.jrc.ec.europa.eu
Check an address
Enter the address: the report summarises risks, local prices, population, services and transport, with the source for every figure.
For example: Via Dante 7, Milan.