In practice, actual conditions will allow for approximately 15-20% lower generation due to the considerable heating of the solar cells.
Specifically, the light intensity is 1000 W/m2, with a spectrum similar to sunlight hitting the Earth's surface at latitude 35°N in the summer (airmass 1.5), the temperature of the cells being 25 °C.
Colloquial English sometimes conflates the quantity power and its unit by using the non-standard label watt-peak (symbol Wp), possibly prefixed as in kilowatt-peak (kWp), megawatt-peak (MWp), etc.
This has very little impact on the total energy generated throughout a year, but saves considerable amount of balance of system (BOS) costs.
Some grid regulations may limit the AC output of a PV system to as little as 70% of its nominal DC peak power (Germany).
Because of these two different metrics, international organizations need to reconvert official domestic figures from the above-mentioned countries back to the raw DC output in order to report coherent global PV-deployment in watt-peak.
[5] In order to clarify whether the nominal power output (watt-peak, Wp) is in fact DC or already converted into AC, it is sometimes explicitly denoted as MWDC and MWAC or kWDC and kWAC.