In the how to test solar panels video that you posted there is no controller connected to the panel.
Voltage tester is not reading solar panel.
Grid tie solar panels with 60 cells are often referred to as 20v nominal panels like the solarworld sunmodule 290w solar panel.
A multimeter set up to read current a is effectively a short circuit but when it is set up to read voltage v it is a high resistance.
All you need is a multimeter.
In this section we outline how to do this using a multimeter to measure current amps and voltage.
Testing the 12 volt solar panel.
The reading should be within 10 of the specs on the rear of the panel.
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.
Test your solar panel regulator sometimes you will want to check that your solar system is performing properly or you may simply want to know what output your panel is giving.
This is not unusual.
It starts to get tricky when you move away from battery based solar systems and the 12v increments are no longer necessary.
Before disconnecting the alligator clips ensure the multimeter has been turned off.
How to test a 12 volt solar panel vs other voltages.
They have too high of a voltage to charge a 12v battery bank with a traditional charge controller but too low of a voltage to charge a 24v.
Whenever you have these two values you can figure out the wattage by multiplying them together.
They tested directly from the panel output itself.
Some exceptions may apply based on panel type.
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.
Testing your solar panel is easy.
Keeping in mind the coefficient common readings are.
100w 12v 36 cell panel 20 22 voc.
If you re the solar panel you are testing is used you may receive a lower reading.
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.
Simply touch the solar panel leads with the multi meter probes matching their corresponding polarity red to red black to black.