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 solar panel amps with multimeter.
After doing your solar panel testing you should find that the solar panel output for the pv panel you built on the make solar panels page is about 18 volts and 3 5 amps.
How to test a 12 volt solar panel vs other voltages.
There are two types of multimeters.
I think i stuffed up explaining the amps setting on this one as some of the megas may have been millis.
Whenever you have these two values you can figure out the wattage by multiplying them together.
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.
Measuring the volts and amps of your solar panel using a multimeter.
In this test a multimeter will be the best tool to know the volt and amps of your solar panel.
Analogue and digital multimeter.
A variable resistance box.
A good quality multimeter an auto range preferably or one that can read current and voltage.
On a quick connect plug b coming from the solar panel the covered female part is the positive lead and the exposed male prong is the negative.
I had a look at dads multimeter and the amps were set out way simpler.
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.
This is an easy way to vary the resistance to known settings while it is fixed in the circuit.
Simply touch the solar panel leads with the multi meter probes matching their corresponding polarity red to red black to black.