solar panel issues

[Kai]

I have tested the short circuit current of two 100 W solar panels from TEMU and found they are under 700 mA in partial cloudy days. Once connected to solar controller, their output voltage drops to almost same voltage as lithium battery's. It means they have about 1 to 5 W charging power. I am going to test again in sunny days. Are they normal or faulty solar panels?

 

[birdman101]

If you put a meter directly on panel leads before going in controller you usually have between 19 to 22volts. On a dull day around 16 volts

 

[Kai]

If you put a meter directly on panel leads before going in controller you usually have between 19 to 22volts. On a dull day around 16 volts

The voltage is correct as specified. But the short circuit current should be above 5A.

 

[Jcloughie]

Do you have another panel which is know to be good you could then do a comparison test in the same sun.

John

 

[JTQ]

IMO best wait till we see the sun before making any judgement, and then ensure the panel is angled "normal" to the sun.

Depending on the technology of the cells employed they respond quite differently to reflected and direct sun beams, but in all cases you need the "light" power to hit the panel for it to generate electrical power.