The main units of measurement in photovoltaics are the watt-crete (Wp) and the kilowatt-hour (kWh).
Watt-peak (W p): the maximum electrical power that can be produced by a photovoltaic device under standard sunlight conditions. These conditions correspond to:
- An irradiance of 1,000 W/m2
- A spectral distribution of radiation known as AM 1.5, corresponding to solar radiation reaching the ground after passing through an atmosphere with a mass of 1 kg at an angle of 45°.
- The panels are positioned to capture the maximum amount of radiation (their plane is perpendicular to the direction of the source of direct radiation).
- A panel temperature of 25 °C
Kilowatt-hour (kWh ): this corresponds to the energy consumed by an appliance with a power of 1 kilowatt that has been in operation for one hour (1 kilowatt × 1 hour).
