To test a 18v solar panel voltage output directly put your solar panel in direct sunlight set your multi meter to the dc volts setting.
How to test a solar panel with a multimeter.
Next you need to set your digital multimeter to amps settings dc after that you will need to set your multimeter to the highest amperage sensitivity to avoid blowing the digital multimeter s fuse.
As most solar panels are 12 volts the solar panel test methods are basically the same.
Tilt the solar panel in order for your solar panel to have full sunlight exposure.
Set multimeter to dc.
Set the meter to above 200 vcd to ensure you get the most accurate reading possible.
How to test solar panel amps using a multimeter the first thing to do is place your solar panel outside in direct sunlight.
You will want to ensure that you place the positive to positive and negative to negative when attaching your multimeter to the connection on the back of your solar panel.