How many Watts or kW is a solar panel? This is an often-asked question.
In this regard, it is important to define maximum power rating (or peak power). For solar panels, this is denoted as Wp (watt peak) or kWp (kilowatt peak). The maximum power rating is the power produced by the solar panel under ideal conditions which could be a sunny day during the noon. The actual power output is the power produced by the panel under real-life conditions.
In the current scenario, solar panels used for solar farms have a rated power ranging from 200 to 350 Wp. But solar panels can be made available for as small as 10 Wp, or even lower!
While Wp or kWp represents the peak capacity, what we actually need is the actual watt at any point in time. A solar panel’s actual wattage at any point in time depends on the solar insolation at that point. So, a solar panel with a peak power of 400 watts will generate 400 watts only if it is kept under standard conditions (a nominal temperature of 25 degree Celsius and solar insolation of 1000W/m2).
Most times during the day, except for a couple of hours, actual wattage of the panel would be less than 75% of the peak power due to real life conditions.