Whenever you have these two values you can figure out the wattage by multiplying them together.
Measure wattage of solar panel.
Under stc a 250 watt panel produces 250 watts of electricity when the sunlight or solar irradiance on the panel is 1000 watts per square meter and the panel is operating at 25 c.
These ideal conditions are simulated in a laboratory where solar panels are tested known as standard test conditions stc.
After doing your solar panel testing you should find that the solar panel output for the solar panel you built is about 21 volts and 5 amps.
The stc measure the solar panel s energy output using common conditions of light exposure orientation and panel temperature.
So under these ideal conditions a 250 watt solar panel will produce 250 watts of electricity.