diy solar

diy solar

Very low RV solar panel output under clear skies?!?!

cottersay

New Member
Joined
Aug 11, 2021
Messages
19
We just set up your Renogy solar system for our RV. It consists of four Renogy 100W 12V Monocrystalline Solar Panels, wired (10AWG) in parallel to a Renogy Wanderer Li 30A 12V PWM NG Charge Controller, then on to our twin 100Ah BB 12V Lithium batteries (in parallel).

We are in Arizona (White Mountains) at almost 10,000 feet with measurements taken under clear skies*, and all of the solar panels are facing due South, angled upward toward the noon-day sun. Here are the pitiful current (Ampere) levels we are obtaining from each of these panels:

Panel #1: 0.49A
Panel #2: 1.38A
Panel #3: 0.39A
Panel #4: 0.46A

The total output current from the charge controller to the RV is only 2.70A.

For the conditions as described above, this is abysmally low, even Panel #2.

Oddly, when a cloud moderately covers the Sun, the current level dips very little.

The Renogy controller has been set to Lithium.

Any suggestions, because the solar system as-is is pretty useless...?


Thank you,

-Cotter

*Clear skies for a few minutes in between a month of thunder, lightning, rain, hail, etc.
 
You won't get any output at all if the battery is charged and there's no load on the system.

Hard to have output if there's nowhere to put the power.

Try turning on as many things as you can.
 
I should have made that clear, but my 200Ah of battery's State Of Charge was only 50% when I attached the solar system to the RV...
 
Something is either wrong with your wiring, controller settings, controller itself, or the battery BMS are cutting off for high voltage from the charger.

Without knowing anything about how any of it is wired we can't begin to diagnose this online.
 
Thanks Winnie, but yes, the panels are very clean from the endless rains we are getting here in "sunny and dry" Arizona.
 
We just set up your Renogy solar system for our RV. It consists of four Renogy 100W 12V Monocrystalline Solar Panels, wired (10AWG) in parallel to a Renogy Wanderer Li 30A 12V PWM NG Charge Controller, then on to our twin 100Ah BB 12V Lithium batteries (in parallel).

We are in Arizona (White Mountains) at almost 10,000 feet with measurements taken under clear skies*, and all of the solar panels are facing due South, angled upward toward the noon-day sun. Here are the pitiful current (Ampere) levels we are obtaining from each of these panels:

Panel #1: 0.49A
Panel #2: 1.38A
Panel #3: 0.39A
Panel #4: 0.46A

The total output current from the charge controller to the RV is only 2.70A.

For the conditions as described above, this is abysmally low, even Panel #2.

Oddly, when a cloud moderately covers the Sun, the current level dips very little.

The Renogy controller has been set to Lithium.

Any suggestions, because the solar system as-is is pretty useless...?


Thank you,

-Cotter

*Clear skies for a few minutes in between a month of thunder, lightning, rain, hail, etc.
Most likely you have a poor connection thru the MC4 connectors or you have a panel with reversed wiring. Did you polarity check these panels before hooking them up to ensure the + and - were correctly marked and had the correct end? If not, and you don't have blocking diodes in place with fuses, you could have a panel being fed amps from the other 3 panels. This actually is potentially a fire hazard. Also, the Wanderer only has 2 ports for pv cables, I'm assuming you are using parallel MC4 splitters?

I eliminated the MC4's on my panels, crimp connectors and heat shrink is the way to go.

Before you start cutting the wires off and crimping it together, I do have to ask why you used a PWM controller and not a MPPT which would have allowed you to run panels in series with less voltage loss on the PV cables? This is all about getting the most watts to the charge controller that are available, higher voltage will get more watts downrange.

Here is how I would approach this problem. Get a multimeter and check polarity of each panel. If this checks out, then you need a backprobe pin, T pins work. https://www.amazon.com/t-pins/s?k=t+pins

You backprobe on the backside of the connector with it connected and read the voltage on the + lead. This is important, you check at the charge controller and the panel connector. You will probably find that somewhere you have resistance in the circuits (low voltage reading) if you make it this far.
 
Thanks Zwy, I have a few wire piercing probes, so I will perform those tests ASAP.
The panels all have blocking diodes, and I carry spares just in case.
I like the idea of eliminating the MC4's, so I just may take the time and solder the wire harnesses together (connectors, of course, are always the big failure point).
I went with a parallel PWM setup because I will have many instances of a tree branch or some other shadow in the way, and I don't want to lose power so drastically as the series MPPT setup would cause...
 
  • Like
Reactions: Mdb
We are envious that you may be near Greer or Big Lake so that's all the help we're going provide. ;)

Yes, we are on the north side of 260, just off 117 and a few hundred yards away from Greens Peak Lookout and the Apache Reservation. Lovely area, but it refuses to stop endlessly raining. I'm getting cabin fever, but we can't seem to find any other areas within a few hundred miles that don't also have such obnoxious weather... (We stay at Lyman Lake and Springerville RV park in between our max 14 day stays boondocking in the Apache Forest.)
 
Panel #1: 0.49A
Panel #2: 1.38A
Panel #3: 0.39A
Panel #4: 0.46A
You have 4 panels in parallel, but 3 of them are putting out only about 0.50A each, and only one is putting out 1.38A (which is still low), I would check all the connections. and wiring.
 
I'd disconnect the panels from each other AND from the controller. Next, I would test each panel separately - the Disconnected Voltage should be correct, and (in a second test immediately after) the short-circuit Amps should be correct. I suspect that you will find a "bad Panel", possibly with almost no voltage on it - and that panel, in addition to being failed internally, can pretty effectively "short circuit" other good panels on a parallel string. Test the Panels first. Please do report back your 4 separate Voltage and Current readings - if the panels seem good, then we can look at the wiring and the PWM Controller.
 
Thanks for all the help, guys! I followed the testing procedures as laid out by rickst29, Zwy, and Short_Shot, and discovered that the solar output current didn't change whether there was a single panel connected or all four connected to the solar controller (about 3A). This led me to believe that the RV's solar wiring may be -- for some unknown reason (but knowing RV manufacturer's sloppiness) -- being sent into some input in the RV's 120V-12V converter; so I attached the solar controller's output directly into the Li battery bank and voila; I was now able to get 17A on this hazy day.
Anyone ever heard of this problem before?
 
No idea in your case.

I do know that some "solar ready" campers have "zamp" branding and are wired with reverse polarity. That's a good way to break things too.
 
Thanks for all the help, guys! I followed the testing procedures as laid out by rickst29, Zwy, and Short_Shot, and discovered that the solar output current didn't change whether there was a single panel connected or all four connected to the solar controller (about 3A). This led me to believe that the RV's solar wiring may be -- for some unknown reason (but knowing RV manufacturer's sloppiness) -- being sent into some input in the RV's 120V-12V converter; so I attached the solar controller's output directly into the Li battery bank and voila; I was now able to get 17A on this hazy day.
Anyone ever heard of this problem before?
So who did install the system? It sounds like they did not perform any test on the system.
 
So who did install the system? It sounds like they did not perform any test on the system.

Hi Bud. I installed the Renogy solar system, and immediately had this problem. But the RV manufacturer installed the defective internal solar wiring at the factory, which should have been rather idiot proof, as the wiring (of course) need only go from the external bulkhead SAE connector located on the side of the RV, on to the forward battery bank. Yet they somehow screwed it up (it was their first year making "solar ready" trailers, if that's any excuse.)
 
Hi Bud. I installed the Renogy solar system, and immediately had this problem. But the RV manufacturer installed the defective internal solar wiring at the factory, which should have been rather idiot proof, as the wiring (of course) need only go from the external bulkhead SAE connector located on the side of the RV, on to the forward battery bank. Yet they somehow screwed it up (it was their first year making "solar ready" trailers, if that's any excuse.)
Sad isn't it? I hope you notify them what you found since I am sure you will not be the only one that run into this problem, and hopefully other people did not pay big money to troubleshoot the problem just to find out it is the RV problem.
 
Thanks for all the help, guys! I followed the testing procedures as laid out by rickst29, Zwy, and Short_Shot, and discovered that the solar output current didn't change whether there was a single panel connected or all four connected to the solar controller (about 3A). This led me to believe that the RV's solar wiring may be -- for some unknown reason (but knowing RV manufacturer's sloppiness) -- being sent into some input in the RV's 120V-12V converter; so I attached the solar controller's output directly into the Li battery bank and voila; I was now able to get 17A on this hazy day.
Anyone ever heard of this problem before?
At least you found it. What brand and mode of 120V AC to 12V DC converter? Maybe it was some type of solar ready converter.
 
Back
Top