Solar Energy Calculators

System sizing, tilt, string voltage, storage and payback. 7 calculators for photovoltaic installs. Turbines sit under Wind Energy.

String sizing is the calculation that protects the inverter, and it has to be run at the coldest morning you expect rather than at standard test conditions. Panel open-circuit voltage climbs as temperature falls, roughly 0.28% per degree below 25°C for crystalline silicon, and too many panels in series will push a winter dawn past the inverter’s hard voltage limit and destroy it outright. Too few and the string sits below the tracking range most of the day, which wastes production quietly instead of loudly.

Tilt angle is not simply your latitude, which is the rule of thumb everyone repeats. Year-round output peaks nearer latitude times 0.76 plus 3 degrees, because a shallower angle catches more summer sun during the months long enough for it to count. Latitude plus 15 maximises winter, and it is right only if winter is when you need the power.

Payback pages want your real tariff, not a national average.