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How to get the most out of a cheap PWM SCC

Leo3

Solar and Wiring Newbie
Joined
Jun 13, 2020
Messages
170
I have this SCC which was OEM installed on my RV.
  • Accepts up to 190 W solar.
  • Max solar panel input voltage 25 V
  • Max solar array current 10 A
I think the OEM installed panel is this:
  • '100 W
  • Voc 21 V
  • Vmp 17.5 V
  • Imp 5.68 A
I also have Bluetti SP120:
  • 120 W
  • Voc 23.7 V
  • Vmp 19.8 V
  • Imp 6.06 A

So my question is, if I take the SP120 up to the roof, connect it to the OEM installed one, is there a way to limit the current or voltage by doing something simple like not unfolding all 4 SP120 panel segments?
 
Most SCC are tolerant of over-current as they just ignore it. You don't want to exceed voltage.

Those two panels in parallel should get you as close to the optimal as possible. The extra 2A should just be ignored.

Read your manual carefully to confirm there are no cautions about exceeding input current.
 
Still, don't forget to fuse the PV circuit for safety... Also should fuse the battery bank circuit as well. :)
 
Still, don't forget to fuse the PV circuit for safety... Also should fuse the battery bank circuit as well. :)
According to the wiring diagram on page 8 of the SCC manual I linked to above, there "should" already be a fuse between the SCC and Batt on the pos wire. However, travel trailer wiring can be hard to follow so I actually don't know. I need a tool to energize the positive wire that exits the SCC so I can trace it. That exists right?
 

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According to the wiring diagram on page 8 of the SCC manual I linked to above, there "should" already be a fuse between the SCC and Batt on the pos wire. However, travel trailer wiring can be hard to follow so I actually don't know. I need a tool to energize the positive wire that exits the SCC so I can trace it. That exists right?

They do make tools called tone generators which I've used before to trace wires:

However, in this case it might be easier/cheaper to see what you can find by other means. They would usually put the fuse for the SCC near the battery since that is the power source in the general sense...

If you find fuses you think might be the one, you can pull that fuse to see if voltage drops at the SCC (first disconnect the PV circuit so it doesn't provide any voltage into the SCC, messing with your readings on the battery bank terminal outputs)... Sometimes you can also make note of the gauge/color of wire, and the brand labelings on the wire itself, to see if you can find the exact wire coming out somewhere else.

You can go to the fuse box and pull all the fuses and see if it's one of those (label all the fuse sizes so you can easily put them back into the right slots), and keep looking. I suppose it's possible the RV manufacturer didn't install the proper fuse from the factory, don't overlook that notion hehe...
 
Probably all sections of the panel need to be unfolded because they add up in series to get voltage.

Panels only produce full current when aimed directly at the sun.
If you tilt one panel at AM sun and the other at PM sun, maybe a 90 degree angle between them, instead of 100 + 120 = 240W you'll only get about 0.7 times that much (under 190W), but power will be spread out over more hours.
Max current, instead of 6 + 6 = 12A will be about 8.4A
 
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