diy solar

diy solar

Unexpectant disadvantage converting from 12v to 48v??

If 8 panels at 12 volts equals 24 panels at 48 volts, something is seriously wrong . . . .

Don
 
you started with (9) 100W panels and now have (12) 100W panels.

So your "new" potential power profile is not vastly different from your old system; were expecting something different???
Changing your battery/panel configuration around does NOT change the power you have (900w vs 1200w); it can greatly reduce your losses due to wire heat depending on currents involved.
 
I missed that along the way as the first post states:
" I wired up 12, 100w panels and now have 2 parallel strings of 6 panels in series."

Yes, I've been throwing panels at this thing trying to increase performance.

I have 24, 100w panels now and barely limping along.

Heck I don't even know what to believe. The LCD on the unit or the lame renogy app on my phone. The app has never shown more than 1400watts of charge power. The LCD has shown over 3000w.

All I know for sure is that I'm sitting here with 2400w of panels in a cloudy day and my batteries are sitting at 50.1v. I will have to run the generator here soon.

My power consumption has not increased much since I switched over to these agms and 48v controller.
 
One thing to consider - Unlike lithiums, you can't throw lots of current at AGM's (or any lead acid battery) and expect them to recharge faster just because you have more PV power available. Could be that's what's limiting the performance of your current setup. You might have been recharging them about as fast as possible with your 9 panels in your original 12 volt configuration, so you're not seeing much improvement with more panels in the 48 volt configuration. I think you would see a huge increase in performance if you switched to lithium

Don
 
Yes there are increased MPPT conversion losses as the voltage differential between solar and battery is increased. The top controllers will have a graph to explain this in the manual. Should not be a surprise.
 
...I think you would see a huge increase in performance if you switched to lithium

Don

yes I think you are right, I think these Renogy 200AH AGMs pretty much just suck.

and so may the Renogy 48V controller.

Really what happened here is I felt sorry for my neighbor who burned and I gave him all my solar, then bought into the 48V inverter charger/AGMs without really giving it any thought.

Oh well, I really like tinkering with solar stuff...
 
8 x 12V x 200 Ah = 19 kWh of battery, same size I have.
Not sure what charge rate they like, but if 0.2C like mine, will take 3800W.
You have 2400W of panels? That's only 12.5C, batteries should accept those until they reach absorption voltage.
You ought to be seeing 45A charge current, or a bit less since that would be 100% of panel STC rating.
 
In the Settings menu, check the value of parameter 36: PV charging current. Should be at default setting of 80A. Someone else had a similar problem and theirs was set to 8A.
 
So it was a charge controller setting not a wiring issue?

One thing to note, now you’re running in strings series if a single panel of a string sees shade it’s affects the entire string. Thus if you have 6 or 8 panels per string, one shaded will have a pretty big impact. If your 12v system had each panel wired in parallel shading plays a much less impact.
 
So it was a charge controller setting not a wiring issue?

One thing to note, now you’re running in strings series if a single panel of a string sees shade it’s affects the entire string. Thus if you have 6 or 8 panels per string, one shaded will have a pretty big impact. If your 12v system had each panel wired in parallel shading plays a much less impact.

yes

at this point I think the Renogy 48v controller/inverter is probably a decent unit. Too bad it's not UL listed though.

I think the Renogy AGM 200ah batteries suck. They don't seem to be able to absorb power (recharge) very quickly and that limits my 2.4kw array from being able to charge them all the way up.
 
Ok so continuing troubleshooting this thing.
...
I disconnected the mc4 connectors from the combiners that I have at the box (parallel) and tested each one. Both pairs were at ~125v. Interestingly enough, I tested voltage at the inverter PV input. 6.1v DC (with nothing connected to PV input).

I connected the mc4 connectors and now the inverter says PV input voltage is 112v and making 2amps. Maybe the connection wasn't good at the combiners?

Seems good now.
Yes. One way is to slightly deform the MC-4 internal electrical connectors. That outside barrel on the female side, may not be engaging good with the male pin connector. You'll feel a definite resistance, slight but noticeable, just before the clipping of the connectors, where the barrel is sliding over the pin. Also, take some copper paste and paint it inside the barrel. That's another way. If it's working now, I suggest adding the copper paste.
 
Do you have some way of balancing the charge between the 12v batteries in the string? I used those chinese 5amp rated ones in a 48v, but they tend to burn up. I tried a 60amp Sure Power military surplus and put the batteries in 2x2 in a 24v config. Tap the first 12v for your loads and the Sure Power will keep them balanced.
 
The batteries in the string may be unbalanced. The 'most full' one will limit the current through the string. Monitoring the individual battery voltages may offer a clue.
When you had the batteries in parallel unbalance was not an jssue.
 
The batteries in the string may be unbalanced. The 'most full' one will limit the current through the string. Monitoring the individual battery voltages may offer a clue.
When you had the batteries in parallel unbalance was not an jssue.
I agree (see above post). This is the problem I had with the FLA's. I used those 5amp chinese balancers (they are about $18 each), 3 of them, but I couldn't find a bullet-proof option. So I split the difference and went to a 24v config, and use the milspec Sure Power.

Later, with LFPo, of course internally they have a BMS. Much better efficiency, 0-100% range (nearly, there is some BMS programming that limits the low-end to 5%), no maintenance, surge charging is not a problem, no 5hr Absorb cycle, no equalization. I would never go back to FLA or AGM (lead-acid).
 
Yes. One way is to slightly deform the MC-4 internal electrical connectors. That outside barrel on the female side, may not be engaging good with the male pin connector. You'll feel a definite resistance, slight but noticeable, just before the clipping of the connectors, where the barrel is sliding over the pin. Also, take some copper paste and paint it inside the barrel. That's another way. If it's working now, I suggest adding the copper paste.
this thread is nearly 2 years old.
 
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