diy solar

diy solar

pannel issue help

photo2000a

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Aug 19, 2021
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A little while ago I bought 2 flexable 50w sunpower panels from amazon about a month apart and from 2 different vendors and a victron smartsolar mppt 75v 15.
my goal was to have the 2 panels charge a small aux batt in my vehicle. i have a small battery matched charge profile. connected to the victron

On my initial set up i ultimately noticed the victron showed good voltage on ea panel, but when i combined them in series the voltage stayed at 1panel voltage for ex. if 2 panels were outputting 15v at the time. i expected to read about 30v in series (which i did if i measured just the cells alone) but when i plugged into the victron voltage measured 15v. can anyone explain this ? was it due to the low current problem ....below

Someone suggested i check the amps, the victron always showed steady zero amps either 1panel or 2 in series. They recommended a few YT videos to test the individual output at the panel both panels read about 20ma at 20v full sun . I thought it odd that 2 panels both had the same trouble, nobody could suggest any other tests at the time so i returned them. figured maybe just bad luck?

I returned 1 sunpowers for an sunpower exchange still waiting for that to arrive and the other i returned and figured id try a renogy which i just got.

Plugged the renogy into my voltmeter got 18v. (cloudy then) and 33ma. tried it into my victron, zero amps. at first i thought the victron might be bad. (maybe it is dunno) but my meters are good. I get that perhaps the victron won't measure as low as 33ma.

I have a small 7w 12v lightbulb incandescent plugged it into the load port on the victron it shows ex 7w so seems least on that port the victron is spot on.

I have a calibrated fluke meter. reads ok across a battery and a resistor , and i have a second meter when i test it on a battery and resistor i got what i expected. so. pretty sure my meter is not bad. since my meter goes pretty high i also just tried measuring across the panel same reading

all the panels i've had visually look perfect as did the box. guessing since i am new to solar maybe i am overlooking something obvious. hoping that someone might be able to suggest. a couple of tests. I can't believe this renogy is bad and bad the exact same way. grateful for any help


 
You seem To be doing everything right. You have checked the meter to be sure it reads amps.

The Victron 75/15 will need around 17 volts to start charging. If you measured 18 volts open circuit, the Working voltage it less, so there may not be enough voltage. You can measure the leads at the SCC’s PV input for both voltage and amperage.

For referece, I have a 100 watt panel 21 volts open circuit, but operates between 18 and 20 depending on the temperature. I have seen it put out 3-5 amps on a sunny day when I measure amperage. You should see half that.

I’m sure you tried this, but if the panels were hooked in parallel instead of in series, they would have read the same voltage.With MC4 connectors, you can only connect one way without making cables, and for the way my panels are wired that’s in series.
 
thanks for responding Chrisski, i do understand the unit woun't charge till condition are correct, but it should always read the v /a of the panel to it's display via the b/t app. and seems my meter and it are showing the same more or less. I was planning on hooking them in series per op, but for testing just testing. single panel. hoping that maybe a few others might chime in, not sure the odds of me getting all bad panels and all bad w/same issue of. volts no amps. really scratching my head .... maybe it's just a amazon thing. anyone know a good online store that is reputable and maybe can check the panel before shipping?
 
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