kilowattpiek

Kilowattpiek, abbreviated kWp, is the unit used to express the nominal, peak DC power output of a solar photovoltaic installation. It indicates the maximum instantaneous electrical power the array can produce under standardized laboratory conditions and is a measure of capacity rather than expected energy yield.

Rating of a PV system is defined under standard test conditions (STC): solar irradiance of 1000 watts per square meter, cell temperature of 25°C, and a reference solar spectrum (air mass 1.5). Under these conditions, a system rated at 1 kWp can deliver up to 1000 watts of DC power at the array level. This rating is typically given for the array's direct current (DC) output, before losses in inverters, wiring, and temperature effects.

Actual energy production is measured in kilowatt-hours (kWh) and depends on location, sun hours, weather, panel orientation and tilt, shading, temperature, and inverter efficiency. Temperature can reduce the voltage and thus the power; shading and other factors also reduce output.

Kilowattpiek is used for sizing and comparing PV systems. It does not by itself specify annual yield. A typical residential installation ranges roughly from 3 to 10 kWp, depending on roof area, energy needs, and local incentives. The exact energy produced per kWp per year varies widely by climate and conditions, so kWp provides a capacity reference rather than a guaranteed amount of electricity.