Hello and a solar controller question

Boatdave

New Member
Hi there, my name's Dave, I'm new here.
I live on a narrow boat in the middle of England. I have a bank of 3 x 12V leisure batteries which power my led lights, water pump, inverter (which I very rarely use,) etc.
I have inherited a 265W LG MonoX PV which I want to use to help keep my battery bank topped up.
I have wired the PV into the system but am getting no solar (sunny icon) charge symbol on numerous 30A solar controllers I've tried, despite getting voltage readings from the PV with a multimeter and the same readings at the controller PV terminals and the controller(s) otherwise seemingly working (battery/temp/etc readings seem fine?)
What am I missing?
Many thanks in advance.
 

snoobler

Solar Honey Badger
Welcome to the forum. What voltage are you reading at the panel?

Please provide a link to the last charge controller you tried.
 

snoobler

Solar Honey Badger
Ouch. Probably worth establishing tests are being conducted in at least high ambient light conditions if not full sun... :)

Assuming this is the panel:


This panel is not suitable for charging 12V systems on PWM. It will perform more like a 120W panel. Furthermore, if installed on a PWM controller that is not capable of 24V, it may damage it or not work at all. The panel has a Voc of 38.3V where a normal 12V panel would be around 21V.

It will work very well on a REAL MPPT charge controller. Emphasis on "REAL" because there are plenty of fake PWM controllers labeled as MPPT.
 

Boatdave

New Member
Hi all, and thanks for your welcome's and replies.
iamrich - you're not far wrong! The tropics it is not...
On the standardly overcast with bright sunny interval days of late, I get between 2.5 - 4 V on the multimeter on the controller PV inputs.
Snoobler, yep, that looks like the panel. The two controllers I've tried thus far are cheap MPPT labeled Chinese controllers off of ebay. The first one I also inherited, the second one I thought I'd try cheap first before diving in.
Many thanks for your time, know how and any further info... it's much appreciated
 

iamrich

Solar Addict
On the standardly overcast with bright sunny interval days of late, I get between 2.5 - 4 V on the multimeter on the controller PV inputs.
This is your problem. You should be seeing at least 30vdc from that panel at the inputs. What does the panel read if you just measure across the + and - wires?
 

Boatdave

New Member
This is your problem. You should be seeing at least 30vdc from that panel at the inputs. What does the panel read if you just measure across the + and - wires?
The same. I'm pretty green when it comes to electrical stuff so could be using the multimeter incorrectly? I've got it set on DCV 200?
 

iamrich

Solar Addict
That's what I would set it at. Red lead to the +, Black lead to the -. I wonder if your panel or the wiring/connector(s) are damaged. What does your multimeter say when you check the batteries?
 

Boatdave

New Member
That's what I would set it at. Red lead to the +, Black lead to the -. I wonder if your panel or the wiring/connector(s) are damaged. What does your multimeter say when you check the batteries?
Yeah, I thought I was in the right ballpark, multimeter wise... it reads the batteries as (currently) around 12.1V, which is the same as both cheap controllers. Basicly, the controller(s) seem to work and the batteries definitely work and the panel gives some reading (around 3vdc on an English spring day) but the controllers don't recognize the panel? Is it looking like the panel isn't giving out what it should? I inherited it, but it is brand new/never been out of its protective case/still had its info sticker stuck on the panel and the friend I got it off works for a renewable energy firm and got it direct through them, so it *should* be as new I'd have thought? The 3ishvdc reading is from the wires coming direct out of the panel under midday patchy cloudy sun...
Thanks, as ever...
 

snoobler

Solar Honey Badger
Hi all, and thanks for your welcome's and replies.
iamrich - you're not far wrong! The tropics it is not...
On the standardly overcast with bright sunny interval days of late, I get between 2.5 - 4 V on the multimeter on the controller PV inputs.
Snoobler, yep, that looks like the panel. The two controllers I've tried thus far are cheap MPPT labeled Chinese controllers off of ebay. The first one I also inherited, the second one I thought I'd try cheap first before diving in.

Those are most likely fake MPPT and actually PWM. Your panel will not work effectively with them if they work at all.

Yeah, I thought I was in the right ballpark, multimeter wise... it reads the batteries as (currently) around 12.1V, which is the same as both cheap controllers. Basicly, the controller(s) seem to work and the batteries definitely work and the panel gives some reading (around 3vdc on an English spring day) but the controllers don't recognize the panel? Is it looking like the panel isn't giving out what it should? I inherited it, but it is brand new/never been out of its protective case/still had its info sticker stuck on the panel and the friend I got it off works for a renewable energy firm and got it direct through them, so it *should* be as new I'd have thought? The 3ishvdc reading is from the wires coming direct out of the panel under midday patchy cloudy sun...
Thanks, as ever...

At the moment this photo was taken, the 3000W array visible on top of the shipping container was producing 800W:

1617972643912.png

While I don't have the panel voltage for that moment, to be able to produce that amount of Watts, the panels should have been producing something close to Vmp at about 33-36V.

It's shortly after sunrise here, and this is what my array parameters looks like:

1617973390287.png

The 3 panels in series are producing 108.4Voc w/0A being output. This is 5 minutes before sunrise during civil twilight.

3VDC on a panel in decent ambient light sounds like a problem with the panel or the measurement.
 

Boatdave

New Member
Thanks guys. I also have an existing, older array consisting of 2x 100W flexible panels wired into an older PWM controller and my battery bank which I get a reading of 2.2 V's off the PV inputs at around the same time/light as I get 3ish V's off the new 265W panel, which kinda seems about right in contrast to one another (265W panel giving 3 V's, 2x 100W panels giving 2.2 V's) As I say, I'm no expert in the slightest, so could be reading it wrong/getting a wrong reading, but that wouldn't explain why the new panel doesn't 'communicate' with various (albeit cheap, probably not the MTTP they claim to be) controllers would it?
Cheers
 

snoobler

Solar Honey Badger
+1

There's no way you're accurately measuring those voltages.

Your panel is NOT designed to work with PWM controllers @12V. It may present too high a voltage for the PWM controller to function.
 

Boatdave

New Member
IMG_8087.JPG
Okay, so here's the PV's. The new 265W panel closest and the 2x 100W panels behind...
 

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Boatdave

New Member
IMG_8088.JPG
Here's the MM reading across the PV inputs on the new "mttp" controller (same as the reading direct from the new panel) Also showing the controller showing 0.0V from the new panel, which is what's confusing me..,
 

Boatdave

New Member
IMG_8091.JPG
And here's the old control panel that the 2x 100W PV's are hooked up to showing 2.2 V's across the PV imputs...
 

Boatdave

New Member
IMG_8089.JPG
And here's the MM and new controller readings of the batteries... I'm putting the 0.3 discrepancy down to the MM being held together by insulation tape and/or the controller being cheap/crap, but for my purposes, the readings are there or thereabouts. I just don't get why the new panel isn't talking to the new controller(s)? Is it as simple as it's too powerful for a PWM (masquerading as MTTP) controller or does the new panel just not work?
Cheers, as always...
Dave
 
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