How To Testing solar panels

[Neal]

When getting my LiFePO4 batteries last fall I asked about testing my solar panels (Solar Energy Systems Indiana). I really wanted them to do it as I was diagnosed with incurable chronic laziness but they told me simply throw a towel over each panel and watch the PV drop on your phone. So today as I'm boondocking at a Harvest Hosts overnight in the heat, running both AC's on my new dual Victron inverter setup, 4 x 330ah Victron batteries, NO GEN... I should test the panels. I wasn't seeing the PV I would hope to get for 10 x 180W panels on the roof but it's not ideal sky conditions either. I brought a long a moving blanket like movers use for protecting stuff when packing up a house as they left one with my mother that just moved so I brought it along to test with.

Sure enough two of the panels were offline as they are wired in series pairs. It's hard to test with partly cloudy skies so I need to test again but I know one panel had an issue with the cover to the box underneath the panel not staying on thereby taking out that pair. Surprisingly the top was just laying there on the roof below the panel so I pushed the contacts in and I think it's reading again and I taped the cover plate back on. I'll see next time with clear skies but the gist is to test your panels cover each panel one by one with a towel and watch your PV readings such as with Victron Connect or VRM, or whatever your gadget may be. Watch for the drop and then move panel to panel. I saw drops about 200W per covered panel.

Simple test but if you rely on solar you may want to check all is working. The towel/blanket test is easy.

 

[Richpatty]

HA! I wondering that some time ago (years) and came up with the towel idea. It seemed to work, so I have stuck with it whenever I was in doubt. But it is good to know that that is what the experts recommend!

Thanks for the info.

 

[Kevin D Pem]

I like checking from the ground! I use the air switches (breakers).

Because My system is not complex, I can put a load on the system and see if the panels are putting out the capacity, or the % they are functioning at!!!

Pretty simple really. A bath towel is All that is needed to cancel out the power from the complete serial array, but that won't tell you if the panels are up to snuff!

My array is to large, so I have to test it in sections because the inverter is lower capacity than the array.

 

[Rich W.]

I check by looking at the output from my controllers (each has its own blue tooth gizmo) and I can tell by the output if all is well: l
Each panel should put out around 29v and 10a. I don’t go by wattage because they never get close enough to their rated 315w for the math to be conclusive. Five panels - 2 on one controller, three on the other. So I would know if a panel wasn’t doing its job, but these are LG panels, around 5 years old, and very unlikely to fail. Of course mine is a very simple system - really just a big battery charger tending to a bunch of aging LA batteries.

 

[Neal]

I was going to get on the roof today but I got good verification all is good now. Peaked at 1336W before going back to shore power.