Only 3w from a 200w solar system

[Littleblackflash]

I’ve 2x 100w renogy solar panels connected to my renogy 100ah battery. It’s quite sunny out but today I’ve not seen over 3w of charge? Any ideas why?

Battery isn’t too hot, panels are fairly cool. I’ve tried unplugging and reconnecting.

 

[Dellmassive]

How they conected?

And post a screenshot of the mppt screen.

And settings page

 

[Littleblackflash]

I’m using a 20a mppt renogy elite charge controller.

 

[Dellmassive]

Got a pic of the panels...

And how you linked them together....

Assuming parallel?, you might have better results in series..... Which will bump up your VOC.

 

[t0mb0]

Panel voltage is healthy, usually (but not always) this drops off if the panel itself is faulty.

Are you sure the battery’s internal SoC estimate is correct? If it was actually full then that would explain it. You can test this by turning some loads on, if the power produced by the panel rises then this could be what’s going on.

 

[Rioja John]

canceled post as @t0mb0 beat me to it.

John.

 

[Littleblackflash]

Thanks all. I’m in the middle of wales in a remote hostel with no electricity or internet.
Panels are in parallel but I could swap to series easily.
I changed the boost voltage to 16v to see what would happen. This morning at 8am and cloudy, it was charging at 11w.

SoC seams correct based on it being fully charged, and then power estimates using the inverter and fridge.

I’m out on my bike today, hopefully when I return it has some charge.

 

[t0mb0]

Thanks all. I’m in the middle of wales in a remote hostel with no electricity or internet.
Panels are in parallel but I could swap to series easily.
I changed the boost voltage to 16v to see what would happen. This morning at 8am and cloudy, it was charging at 11w.

SoC seams correct based on it being fully charged, and then power estimates using the inverter and fridge.

I’m out on my bike today, hopefully when I return it has some charge.

Not sure what you mean by some of that but if you’ve set the charge voltage all the way up to 16v that’s a bad idea - it’s surely way over the recommended charge voltage for the battery?

The charge rate going up to 11w at 8am when cloudy is consistent with the theory that the battery was actually very nearly full before when charging at 3w because the battery would have run down a little overnight and therefore allowed some more charge back in.

 

[dErZ]

Could you test each panel individually, ie connect one to your mppt and then the other..

 

[Littleblackflash]

Each panel tested individually gives half the total of them combined. So I assume each panel is working the same.
I did a quick test with them in series, but it didn’t charge at all.

I think battery voltage is correct. I charged it fully before I left. I’ve boiled a 800w kettle a few times which uses 4-5. Ah, and I’ve had my fridge on a few hours. The fridge uses 6-7amp because it’s a 3way fridge, not a compressor one. The battery level is consistent with the amount I’ve used it.

 

[Littleblackflash]

Screen shot was the solar panels connected in series

When I returned tonight, it failed to charge anything noticeable during the day

 

[t0mb0]

Hmmm, that is a bit of a puzzle if that SoC is correct then.

If each panel individually is the same it’s unlikely the panels themselves are faulty - unless they’re both faulty in exactly the same way which seems unlikely.

Could be wiring/ground issue between the mppt and the battery. Have you got a voltmeter, or does the battery report its own voltage? If so, when the MPPT reports 14.4v output or whatever, does the battery report the same or very similar? If not, could be a dodgy connection between the MPPT and the battery.

It could always be some genuine issue with the battery/controller or configuration too.

Do you have a DC-DC charger? If so, what happens when you run that, does the battery see charge then?

 

[Littleblackflash]

Thanks again for your help. It’s a temporary install of the system until I have it all working. Currently there is in the solar mppt and a battery. The inverter is disconnected.

The same happed this morning, I started to see some change before 8am but it dropped off soon after.


7:55 am, and then at 8:38 is was


The mppt earth is directly on the battery, but I agree it could be an issue. I’ll check it.

I may connect the inverter up and pull a current to see if this triggers a change. The battery and mppt report the same voltage. They are both renogy products using the same app. The solar is also renogy.

I’ve a dcdc50, but it’s not connected yet

 

[Grim Reaper]

Have you had the battery disconnected while the solar panels have still been connected at any point? I have heard of solar controllers burning out because the battery has been disconnected and the power from the solar input has nowhere to go.
Always connect battery first and disconnect last when doing any maintenance on solar systems to be sure.

 

[Littleblackflash]

It’s all working again, but I’m not sure why.

I disconnected everything and turned the battery off using small blue cable with the switch on the end. Once I connected everything I switched the battery bms back on and it’s all working fine. The annoying thing is I don’t know why it stopped, so although it’s working, I’m not sure it’s fixed. Time will tell

 

[t0mb0]

It’s all working again, but I’m not sure why.

I disconnected everything and turned the battery off using small blue cable with the switch on the end. Once I connected everything I switched the battery bms back on and it’s all working fine. The annoying thing is I don’t know why it stopped, so although it’s working, I’m not sure it’s fixed. Time will tell

Haha, the classic turn it off and on again fix! Not relevant to AGM but I guess lithium has a load of extra logic in there that might get itself confused and benefit from a restart - could always have been the controller too.

Glad it’s working though!