Ohms Law Load Amp Resistance Change

John1397

I have a solar cell that is rated 3.6 amps .5 volts 1.8 watts when you take a ammeter it does put out 3.6 amps, but this is basically a dead short reading. What I want to know is these cells put out .5 volts using ohms law how much resistance is needed to have a voltage output of .3 volts so you can then measure how many amps are flowing?

I know you could do this with a pot, ammeter, and voltmeter connected to the solar cell then as you start turning up the resistance the voltage output will drop from .5 volts to .3 volts then you can see how many amps are flowing. but it seems that you should be able to figure this out using ohms law?

This is basically a two step problem first find resistance then amps. What I am working on is a solar panel that has 39 cells and when tested it does put out 3.6 amps and has 24 volts no load and what I want to know if this is connected to a battery and the voltage output drops to 12 volts how many amps are flowing at this point?

John

nsaspook

This might help: http://www.ni.com/white-paper/7230/en

The vi curve is not linear and each type of cell requires "Characterization".
Most commercial panels supply this data. Example:http://files.sharpusa.com/Downloads/...ow_NE80EJE.pdf

John1397

One could use a transformer as an example instead of a solar panel.

John

nsaspook

One could but why?

A typical power transformer within it's normal operational specifications can be very linear to changes in load, a semiconductor P-N junction solar cell operated at it's optimum power point is not.