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.
How to test a solar panel with a multimeter.
Measure at higher volts than what your panel is approved for.
Tilt the solar panel in order for your solar panel to have full sunlight exposure.
As most solar panels are 12 volts the solar panel test methods are basically the same.
You want to choose a voltage range capable of displaying the maximum possible voltage of the panel in open circuit this means that if you have a panel rated for 20 volts you should set the multi meter to read up to 200 volts to ensure that you receive an accurate reading.
Make sure that you are measuring at the suitable voltage level for a solar panel.
Set multimeter to dc.
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.