Measuring Voltage of a solar cell with a multimeter
To measure voltage, the black probe should be in the black multimeter port (usually labeled COM) and the red probe should be in the red multimeter port labeled “V”. For some multimeters, this may be the same port as you used to measure current. It may be labeled “VMAW”, or something like that, instead of just “V”.
You can attach the probes with the load hooked up, as shown in the figure below. You can also test with no load attached, by attaching the probes to the wires of the solar panel. You will get a higher voltage when you measure with no load attached (open-circuit voltage) than when you measure with a load attached to the panel. Make sure the meter is set to DC volts, not AC volts. Again, if you get a negative number in the display just reverse the probes.
Measuring Current from a solar cell with a multimeter
To measure current, the meter must be wired into the circuit in series, and the circuit must be closed (all connected) for current to flow.
Most multimeters will measure up to 200 mA (milliamps), and some have an additional port to measure up to 10A (amps, 1 amp = 1000 mA).
In either case, the black multimeter cord will plug into the black (negative) port on your meter. For low currents (200 mA or less), you will usually plug the red multimeter cord into the red port labeled “mA”. To measure a current greater than 200 mA, you will need a multimeter with a “10A” (10 amp) port.
Attach the multimeter into your circuit.
Turn the multimeter dial to the DC mA or DC “10A” setting, depending on how much current you expect (not the AC setting. The DC setting has a symbol that is a solid line above a dashed line).
If you get a negative sign on the multimeter display, just reverse the black and red probes – you have them hooked up backwards.
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