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 be there and hit the panel for it to generate electrical power.

 

[IanB1485]

So many people fall for this , thinking the solar panel will deliver the max output , remember the the panel will only produce its max rated power in full sun and at when at 90 degrees in both axes to the sun.Also as we are in the winter months the sun is lower in the sky and even at noon the incident light intensity from the sun is lower as the light has to travel further through the atmosphere. As the other posters have said wait for a sunny day in June before judging the panels ( or buy a 1000W light bulb ( metal halide or HP sodium) and illuminate the panel with that and measure its output)

 

[toad a caravan]

Ian could you please inform me of which day in June you are referring to I can then put it in my diary and set my alarm so as not to miss it,many thanks Gary. 😄

 

[birdman101]

Ian could you please inform me of which day in June you are referring to I can then put it in my diary and set my alarm so as not to miss it,many thanks Gary. 😄

In theory it should be June 21 the longest day

 

[toad a caravan]

Birdman,Ok I'll set my alarm for 4.54 am to get maximize the sunshine ,thanks

 

[JTQ]

Interestingly, at least to me, unless my Morningstar's meter is miss reading I have seen occasions where the Wattage read exceeds the panels rating, few but not many times. [it's an engineering thing this recording of data!]
I am assuming this is because the rating, as I know is based on a particular illumination standard, not necessarily the best illumination we might ever see.
Further interestingly this still happens on my now 19 year old Kyocera 85 Watt panel, so its not aging badly; though it is only used when camping, so in total it lives much of its life out of the light.