Trouble Shooting

[HARG Hunter]

I just installed my 3rd panel this weekend.
Before I left today, the sun was hitting the panels fully and the controller was telling me the panels were only sending 22 volts / 8 amps to the battery bank.

Tell me where to start troubleshooting.

Here is the set-up:
(3) 100 watt Renogy Mono panels
*They are connected to the Rover Elite 20 amp MPPT controller with 10AWG cable on a 40 foot run.
I have 190 ah worth of AGM batteries (All 3 months old or less):
(1) Universal Power Group 100ah AGM
(3) Mighty Max 30hm AGM's
Batteries all connected to each other with 6 or 8 AWG cable
I have a 12v DC water pump wired directly to the battery bank, with a switch.

A few details....
It has been in the 30's lately, and the battery bank is in an unheated cabin.
It's heated at 65+ when we're there.
The Rover Elite does have a temp sensor, so it should adjust for the differences in temps when we're there or not there.
Sun is low in the sky right now, but I do adjust the angle for the time of year, so the angle is almost exactly where it should be.

In full disclosure, it was 10 am when I checked before I left.
Inverter was not even connected to the battery bank when I checked to see what the panels were sending, so there is no draw.
I know that shouldn't matter, but I'm just trying to make sure I've got everything covered.

Maybe I'm not being patient enough.

Thoughts?

 

[snoobler]

First, I doubt it was sending 22V and 8A to the battery. It definitely can't send 22V to the battery, but it can pull 22V from the panels. That's 22V*8A = 176W, which might be pretty good from 300W of panels in the winter not at high noon.

It's important to know BATTERY voltage and current.

I don't know that I see anything wrong, but there's insufficient information to be certain.

 

[Bob142]

Was that 8A and 22V on input to the Rover Elite? 176W out of a 300W array in winter morning sun doesn't sound bad to me.

I checked your prior post and it looks like you've got the panels in parallel. Are you concerned about partial shading of the array throughout the day? If not, I'm wondering if you'd get slightly better production with them in series.. The Elite will handle it since it's rated to 100V. That might give you a bit of a boost and ensure you're in MPPT mode and not sitting in PWM mode (although if it's reading 22V that doesn't sound like you are).

 

[Bob142]

First, I doubt it was sending 22V and 8A to the battery. It definitely can't send 22V to the battery, but it can pull 22V from the panels. That's 22V*8A = 176W, which might be pretty good from 300W of panels in the winter not at high noon.

It's important to know BATTERY voltage and current.

I don't know that I see anything wrong, but there's insufficient information to be certain.

Dude, it's getting impossible to beat you to any answers on threads! Is this your full time job now?

 

[snoobler]

Dude, it's getting impossible to beat you to any answers on threads! Is this your full time job now?

LOL... literally the first time I checked all day long. Just good timing on that one.

 

[Bob142]

LOL... literally the first time I checked all day long. Just good timing on that one.

I gotta take a typing class so I can get my posts out quicker, just in case.

 

[Jim Burrow]

My panels are 300 watts each at 39 volts (OCV) and 9 amps (ISC) so all I can get and I measured for the fun of it with a panel connected to nothing and that is what I got, 39v and short circuit current (ISC) of 9 amps, just as the documentation specified.

So I think the 9 amps you are reading is what it is supposed to be in full sun.

But note, I haven't installed my panels yet as I am saving up money to buy the batteries therefore I don't have the experience as everyone else on this forum.

 

[HARG Hunter]

First, I doubt it was sending 22V and 8A to the battery. It definitely can't send 22V to the battery, but it can pull 22V from the panels. That's 22V*8A = 176W, which might be pretty good from 300W of panels in the winter not at high noon.

It's important to know BATTERY voltage and current.

I don't know that I see anything wrong, but there's insufficient information to be certain.

You are correct. the 22v is what the panels are sending to the CC.

The more I'm thinking about all of this is that the set-up is doing what it's supposed to be doing.
In spring I may add a 4th panel and wire them in series to make it 24v. I am going to let this set-up do it's thing over winter and see how it goes. I know in summer it will give us more than enough for our needs.

 

[snoobler]

Confirm with battery voltage to be certain. If the battery is in absorption phase where it's at peak voltage, it will only pull what it can use from the array - not the full array power.

400W is the max I'd put on 190Ah of batteries.

 

[HARG Hunter]

Was that 8A and 22V on input to the Rover Elite? 176W out of a 300W array in winter morning sun doesn't sound bad to me.

I checked your prior post and it looks like you've got the panels in parallel. Are you concerned about partial shading of the array throughout the day? If not, I'm wondering if you'd get slightly better production with them in series.. The Elite will handle it since it's rated to 100V. That might give you a bit of a boost and ensure you're in MPPT mode and not sitting in PWM mode (although if it's reading 22V that doesn't sound like you are).

Correct. I think I'm not being patient.
Definitely considering adding a 4th panel in spring and wiring in series to go with a 24v system.

Again though, I think I just need to sit tight and see how this system does it's thing.

When I get up there after being gone for a few weeks, where should I expect the battery bank to be?
Seems like the highest it ever gets to is about 13.1 or 13.2, and with a very light load on the batteries, they drop to 12.0 within a day. I know there's nowhere near enough info and variables I'm providing, but if I have a general baseline on where my battery bank should be, it would help with my expectations.

 

[HARG Hunter]

Confirm with battery voltage to be certain. If the battery is in absorption phase where it's at peak voltage, it will only pull what it can use from the array - not the full array power.

400W is the max I'd put on 190Ah of batteries.

I will probably add 1 more battery before all is said and done.
Probably 1 more of the Universal 100ah AGM's.

 

[HARG Hunter]

We are in the woods, so I'm not sure wiring in series would be best. I do get 3-4 hours of shade-free sun, but the rest of the day is partially shaded.

 

[Bob142]

SO...I'm being told by others that I'd be best served wiring the 3 panels in series.
These panels actually have a 21.6 voc rating, so that would bump me up to 64.6 volts to the CC.

Thoughts?

I concur. See my initial response.

 

[HARG Hunter]

I concur. See my initial response.

I was shuffling back and forth between several sites.
Still wondering if series is my best option, as we are in a wooded area (See pic).
We do get 3+ hours of shade-free sun, but the rest of the day we'd lose quite a bit.
Wondering if that 3+ hours would provide a bigger "jolt" than the array being in parallel and get a little more total throughout the day. I might have to experiment.

 

[Bob142]

I was shuffling back and forth between several sites.
Still wondering if series is my best option, as we are in a wooded area (See pic).
We do get 3+ hours of shade-free sun, but the rest of the day we'd lose quite a bit.
Wondering if that 3+ hours would provide a bigger "jolt" than the array being in parallel and get a little more total throughout the day. I might have to experiment.

There's one way to find out... try it each way for a period of time and stick with the winner.

 

[Bob142]

I'd also look into a proper Coulomb counting shunt-based battery monitor rather than relying on voltage. I can't remember if that's been discussed in your threads before.

 

[HARG Hunter]

I'd also look into a proper Coulomb counting shunt-based battery monitor rather than relying on voltage. I can't remember if that's been discussed in your threads before.

Any specific recommendations/links for a shunt monitor that would match my system well?

 

[HARG Hunter]

I'd also look into a proper Coulomb counting shunt-based battery monitor rather than relying on voltage. I can't remember if that's been discussed in your threads before.

Found a link to this one in another thread. Good Match?

Coulomb Shunt BMS

 

[Freep]

Found a link to this one in another thread. Good Match?

Coulomb Shunt BMS

Aili has been used a lot. It's what I have.

AiLi Voltmeter Ammeter

 

[Bob142]

Found a link to this one in another thread. Good Match?

Coulomb Shunt BMS

I'm partial to either the AiLi that Freep linked or the TF03K. While the AiLi offers more precision in V and A readings, I currently prefer the TF03K because it has everything on one screen, including time remaining at present load, it and doesn't make me calculate Watts (the AiLi does).

TF03K DC100V 350A Battery Power Display Voltage Electricity Current Meter | eBay

Current: 350A. 1 x 10~120V 350A Battery Capacity Tester. Current acquisition accuracy: +/- 1.0%. The actual remaining battery capacity display, high precision capacity indicator. Type: Battery capacity tester.

www.ebay.com