Is there a way to determine the amount of current that can be drawn from a solar panel based on the voltage? Say you have a 100 Watt solar panel. If you measure 24 volts and then later 20 volts can you say anything about the current being produced? P = IV but if there is no load connected then you are getting the open circuit voltage right? I want to measure the voltage and say I can power a device that draws say 50 Watts or two devices that draw 30 watts each.I dont mean predict future current just at the instant the voltage is measured.