RV solar set up - strange issue

[AndyCarter]

Hi,

I have a problem with my solar set up on my travel trailer that I'm hoping someone can help with. I'll provide as much info as I can:

100W solar panel on the roof
GoPower! GP-PWM-30-SQ charge controller (now on my second unit - first one was replaced by the manufacturer for doing exactly what the second one is now doing - described below)
12V wet battery

All of the above is factory install - we purchased the trailer new earlier this year.

When we first got the trailer, solar system seemed to be working as it should.

A few weeks ago, the charge controller started to occasionally give a reading of "low solar" in bright sunlight.

Did some troubleshooting with the manufacturer - checked voltage from the panel - was within spec (about 20V in bright sunlight). Checked amps - ditto - about 3 amps in bright sunlight.

Battery voltage read the same at the battery terminals as the charger was displaying.

They sent me a new charge controller.

Connected the wires (battery first, while solar panel was covered with a heavy moving blanket, then solar panel). Set the battery type to wet.

It registered solar energy (solid red LED) and charging (solid blue LED) BUT was not reading any amps / Ah and was not causing the battery voltage to increase (i.e. was not charging).

Yesterday, I disconnected the solar panel, took voltage and amps readings (both where they should be) and when I reconnected it, it fired up and actually was charging the battery - showed 3.1 amps and the Ah started ticking up as time went by.

I figured I had it licked.

Today I just took a look - it's beaming down bright sunlight and the sun is almost directly overhead, and it's giving me "low solar" again. So I disconnect the panel, take a reading - all good. Reconnect, and it starts working properly again.

So I guess my question is - what would cause this thing to read "low solar" when it's clearly about as good as it gets in terms of solar power AND why is it all good when I disconnect and reconnect?

Keep in mind, this is a replacement unit they sent me (charge controller) due to this behaviour on the first unit. While it's possible, I'd be surprised if I received two defective units in a row.

Also keep in mind, the first one worked great for a few months, then it started doing what I describe above (first unit) and now same thing is happening on the replacement unit. This would suggest that the issue is not the charge controller.

But if it's the solar panel, why does it give good readings, and then everything works great when it's reconnected?

Hoping someone can sort through this and give me some ideas.

I have ordered a new charge controller made by a different manufacturer to see if I get similar results, and then at least I can rule something out as the issue.

Thanks for any help you're able to provide.

Andy

[SunEagle]

Some CC's just start to fully charge when they are first turned on but throttle back when the battery is "full". Have you tried to discharge the battery a little to see if the CC starts back up to fully charge it.

[AndyCarter]

Hi - battery was discharged down to about 12.3V yesterday and then once I did the disconnect / reconnect it started to charge it up. Today when I did the disconnect / reconnect it charged up to 14.7v and then it dropped down to 13.6 as it did a trickle charge.

Not sure if that helps. I can certainly try discharging the battery the next time it gives the low solar message to see if that makes a difference.

[chrisski]

Charged up to 14.7v and then it dropped down to 13.6 as it did a trickle charge.

That seems normal to me.

You can get a hydrometer and do cell measurements on the battery to check them. The battery manual may give a range where equalization is necessary. My trojan's have three sets of parameters including "every 30 days."

A charging problem could be a bad connection also, anywhere along the line from the solar panel through the MC4 connectors, to the SCC in and out connections, to the busbar, to the battery. Bad connections include loose or deformed pins in connectors and oxidation on the leads. Could also be frayed wires. Not on solar setups, but on vehicles I've seem wires that pass continuity tests that are actually a thicker gauge cable frayed, but when real amps are pushed through there's a lot of loss.

[AndyCarter]

Yes - agreed that is completely normal.

My issue is this: charge controller will read "low solar" intermittently, and in very bright sunlight. When I disconnect the panel and reconnect it to the controller, it works great again.

And again, this is a brand new replacement controller where we determined the original controller was defective due to this behaviour. But now it's happening again.

[ewarnerusa]

I googled that controller and looked at the product manual and did not see any instances of "low solar" when searching the document.
https://s3-us-west-2.amazonaws.com/c...-PWM-30-SQ.pdf
IF that is the right manual, are you saying that the controller is giving the "solar panel weak" warning? It seems from the manual that it could provide that value if the batteries are full enough for the controller to have throttled back the charging current to <1 amp. But things are working as intended.
How about turning on some 12V loads on the system next time it is showing low solar like turning on a bathroom fan/range hood fan and a bunch of lights. If the controller switches to a normal charging state when this happens, then it seems that the controller is working as intended.

[sdold]

If the first unit worked OK for a few months but recently started doing this, and the replacement unit did this out of the box, it makes me wonder if it has to do with the season, either heat, better sun angle causing the battery to charge sooner, something like that.

[AndyCarter]

I googled that controller and looked at the product manual and did not see any instances of "low solar" when searching the document.
https://s3-us-west-2.amazonaws.com/c...-PWM-30-SQ.pdf
IF that is the right manual, are you saying that the controller is giving the "solar panel weak" warning? It seems from the manual that it could provide that value if the batteries are full enough for the controller to have throttled back the charging current to <1 amp. But things are working as intended.
How about turning on some 12V loads on the system next time it is showing low solar like turning on a bathroom fan/range hood fan and a bunch of lights. If the controller switches to a normal charging state when this happens, then it seems that the controller is working as intended.

yes another poster suggested this as well. I did try this but to no avail. Perhaps I need to do it for longer. Thanks for the tip, and for doing some research on this. I really appreciate the help.

that is the correct manual, yes and yes it’s solar panel weak that the flashing red LED is indicating. When the batt is full and charging stops it reads “FULL” on the screen, with solid red LED (indicating yes, we’re getting solar energy) and blue LED off (meaning, we’re not charging though).

[AndyCarter]

If the first unit worked OK for a few months but recently started doing this, and the replacement unit did this out of the box, it makes me wonder if it has to do with the season, either heat, better sun angle causing the battery to charge sooner, something like that.

yes it’s possible. I wondered about temperature too. It was cooler in the first few months. Hotter now.

Here is some new info though. Today I installed a new controller made by a different brand (The renogy adventurer). The thing has been working like a champ all day. BUT - when I was installing it I noticed that the positive wire from the PV had about half the copper “strands” within the cable cut off. In other words the full diameter of cable was not connected. So the wire gauge was completely different at the point of connection to the controller than the rest of the cable. I cut this part off and Installed the full cable width to the controller.

could this have caused the issue with the controller thinking solar power was low when it was sunny out?

[AndyCarter]

Honestly, I think this particular model of charge controller is just finicky. I’ve installed a different brand and have been out many times to check on it, and it just keeps plugging away exactly as it should. I’ll update here if anything changes

[Mike90250]

Or maybe the "missing" copper strands intermittently shorted the PV output