debugging solar

[pconroy]

So I could use a "shove in the right direction."


My Solar is all DIY. Two 100 watt panels, an EPEver 30A MPPT controller. One group 27 (for now).


It's working. It's keeping the battery charged.
But I don't think it's working right, or even close to optimal.


The first 100 watt panel is two years old. I started with it, just one 100 watt.
I added the second 100 watt panel a month ago - wired parallel.


Wire from panels to controller is 10g stranded from Home Depot.


Thing is I just started watching the power output.


Today is FULL SUN, No Clouds, Noon in Denver.
I'm getting 30 watts.



Looking back at historical data, the best I've ever done is 85 watts from the two panels.


Does that happen?


I *am* plugged in and the battery is fully charged.
Is that what's happening?
The controller is smart enough to dial down the wattage since it's not needed?


If I unplugged and discharged the battery - will I see the controller display more wattage from the panels?




[ As I'm typing this, I think I'll try that now. Unplug. ]


But I'm a bit confused and wanted to hear from some of you.
Thank you!!!

 

[JimD]

The controllers are indeed smart and will adjust themselves to what is needed. I recommend loading your battery to bring it down to a point it needs a fairly heavy charge and see what you read.

I watch my Renogy mppt controller and noticed that the max it seems to put out is just over 100 watts even though I have 2 100 watt panels. I will be adding a 3rd panel soon (as soon as I can get my son to climb up there). When we do this I will be troubleshooting my system.

I made my own solar tester where I can switch different load values into the circuit. I am going to connect my load tester directly to the cables coming from the panels and see what they are capable of putting out.

 

[sciencenerd]

Yes, that's how it is supposed to work. For my solar, when the battery is fully charged, I get a max of 1.5 A (about 20 W), depending what is on in the trailer. My base load with nothing on but the CO alarm is about 0.5 A, so that's what the charge controller supplies when the battery is full. My guess is, 30 W is your base load, although that seems high.

To see the full wattage, the battery has to be at least partially discharged, so the charge controller goes into bulk charge mode.

 

[Screwby]

Same here, I was worried when I saw I was only getting around 2 amps from my solar system before I realized that was the smart controller just keeping things topped off. If I draw the batteries down then the amps start pouring in again.

 

[pconroy]

Thank you!!!

 

[RogerR]

You could do a small test. Place some cardboard over parts of the solar panels and see if your output changes. Should stay the same until you are almost fully covered. Or use some cloth to way cut back the sun on them.

 

[Pickledill]

If it is plugged in and batteries are charged you will clearly get next to nothing through charge controller by designed and for good reason. As others have said, unplug, after all that is what solar charging is for, and observe at roughly 12.3 volt reading state of discharge what controller is outputting. My guess in full sun with pwm controller about 12 amps, more with mppt.