Open circuit voltage is reduced on victron 115watt panel after first use

DIY
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1

hi,

I have been thru 8 victron 115watt 6 amp panels (SPM041151202 115W-12V Mono 1030 x 668 x 30mm series 4b) and i test open circuit at around 21.5volts before connecting one at a time to my 100/50 mppt which is connected to 2 *170amp lithium batteries in parallel.

Once the controller kicks in , the voltage is reduced to around 16 volts, tho i can get 4 to 6amps out of them. But that voltage doesnt get me up to 14.6 volts to charge batteries, only about 13.2v.

when i disconnect panel and retest open circuit i only getting around 20v, with the last panel was 19.4 volts on the mc4,s , and by connecting the mc4,s together , i measure 5.56amps with clamp meter.

I have mc4 to anderson lead adaptor and its only like 1m long, so voltage drop over cable length should not be an issue, and i have had portable panels connected on 6m leads with no issue, which i again tested a 200watt blanket and it was giving 18.5 to 20 volts. i also tried my other 100/50 mppt with same result and also a 25amp dcdc.

Seems like after the panels first load on it, it never gets back the ovc from brand new and only get about 70 to 80 watts from panel.

I had a frame made to take three of these panels and be on the roof of my car to run fridge, starlink and i have 2 routers and a security camera, plus cerbo, and it always draws atleast 1.2 amps.

I am in touch with dealer and gave them access to my cerbo, but i think they are also stumped.

anyone have any ideas or solutions please

thanks

3

because all 3 panels dont fit on my roof, with the starlink dish. so had a frame made that allows 2 panels to be exposed while driving, and a swing arm that takes a panel that is directly over another and exposes it when parked up. so parallel is only way this sytem will work.

5

i did do a test with first lot of panels and from memory was getting around 60volts , but amps were poor. there is issue withe the panels, but cant figure out what.

7

this will be third time ,lol. i did initially think it may be a batch issue, do know if this common with victron panels?

9

guess i came to the wrong place for any constructive help. maybe you, in your wisdom, should advise victron to stop supplying 12v panels.

11

If you are driving, then you can charge from the alternator…
Also, the panels should have bypass diodes, so for 3 in series, if 2 are in sun and one not, the panels will still charge…
Voc of a panel will drop when it’s warm. If you are using low voltage panels - Voc 21V, Vmp =17.5V, then you may be better off using a PWM charger, not an MPPT.

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