Great question! When working with photovoltaics, (solar electric panels, solar, or PV), each PV cell gives about half a volt. So while it isn't the sun that is producing the voltage, it is the PV cells reaction to sunshine.
We measure the power, (the amount of work that can be done), in watts. The sun gives us plenty of power to do all the work we do on earth. The conversion efficiency from the sun's rays to electricity is about 10-20%. We need to put up enough panels to produce the power we need for the work we want to do.
The sun's power output varies throughout the day. First thing in the morning there is low irradiance, (the power in the sun). At noon on a cloudless day, the irradiance is a a maximum, and then at dusk the irradiance is low again. Above the weather and atmosphere, the sun's irradiance follows a bell curve.
Energy is power over a period of time. Energy is what we use to get work done. For instance, that one PV cell is probably putting out around 5 watts, and if it was in the sun for 2 hours in the middle of the day it would make 5 watts * 2 hours = 10WH, (or 10 watt-hours).
Here is a link for charts showing the sun's average daily energy for different locations on the earth:
https://kids.kiddle.co/Insolation In general, the closer to the equator and the less clouds, the higher the energy at that location.
Hope that helps,
Kelly Larson