RV charging issues

[FJimmy]

Hi guys,
I'm hoping I could get some help with an issue I'm having.

I have 2x 250W panels fitted to my RV roof.

The cables from the PV go to a 12v 20A breaker, then to a 60A Renogy Rover SCC, PV input terminals. Two cables from the batt output terminals to go to a 12v 63A breaker, then to positive and negative busbars. Connected to the busbar is a 12v lithium battery. The SCC is reading ~3v in.

The manual suggests checking the polarity of the input cables, and ensuring that the cables are secured tightly. I have done this, replaced cables, and removed the circuit breakers. I have confirmed ~19-20v at PV in, before and after the first breaker. I've replaced the SCC with a different SCC and have not seen a difference. I've connected a 160w portable panel to both SCC's, which charged my batteries.

Any ideas? I'm stumped.

 

[Tomthumb62]

Have you tested the 250w panels? I mean, disconnect them from the system at the mc4 connectors and use a multimeter to test voltage and amps in full sun. If you’re not seeing something close to the VOC number listed on the back of the panel, then something is wrong with your panel.

 

[FJimmy]

Have you tested the 250w panels? I mean, disconnect them from the system at the mc4 connectors and use a multimeter to test voltage and amps in full sun. If you’re not seeing something close to the VOC number listed on the back of the panel, then something is wrong with your panel.

I haven't yet. The connectors are hard to get to, but I guess I can try. I've measured the voltage before the SCC; 19-20v. I can check the current with a clamp meter, but I'm working during the day and only have weekends. Haven't had a chance yet.

Thanks for the suggestion.

 

[Tomthumb62]

I haven't yet. The connectors are hard to get to, but I guess I can try. I've measured the voltage before the SCC; 19-20v. I can check the current with a clamp meter, but I'm working during the day and only have weekends. Haven't had a chance yet.

Thanks for the suggestion.

I had one of those Renogy charge controllers, the 30A model. The display is notorious for showing incorrect values. I dealt with so many quirks with that thing and turn their customer service simply drove me batty: very friendly but inept at helping and kept asking for the same info repeatedly, even after I gave it to them more than once.

I replaced it with a Victron 100/30 and not only has it just WORKED, I’m getting about 30% more production than the Renogy, presumably due to the super fast MPPT tracking of the Victron.

With only 2x250W flat mounted panels on your roof, you don’t need a 60A controller. 30A would be fine except in peak summer you’d just be clipping some sun, but for the rest of the year you’d probably not clip much. No harm in clipping, just wasted energy.

Also, what’s the specs on those panels, particularly the VOC? If you have them wired in series you may have exceeded the PV voltage input of your Renogy charge controller.

 

[FJimmy]

I bought the 60 amp SCC when I had 3 370W panels fitted to the roof of my RV. The roof collapsed due to excess weight, so I had the repairer fit these other panels.

I did some more testing and I'm quite confused:
Circuit breaker open: 0A, 20V
Circuit breaker closed: -14A, 3.3V
Circuit breaker closed (5 minutes later): +16A, 3.3V

Why is the current polarity changing? Am i insane?

I connected a portable solar panel to the Renogy 60 amp charger and it worked fine, so i know the SCC isn't faulty.
I connected the RV solar panels to a different SCC, no charge.

I'll need to take the panels off the roof and see how the panels are wired. I just have PTSD due to the previous incident.