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Old 04-06-2017, 07:10 PM   #21
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Renogy panels and Zamp

Yeah the Renogy solar panels use 12 gauge cables and the Zamp supposedly has 10. (Smaller gauge=bigger wire). So that's all good. You want the cables to link directly to the battery. Here's all I did on my old rig.
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Old 04-07-2017, 07:20 AM   #22
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Quote:
Originally Posted by wherewolf17 View Post
Yeah the Renogy solar panels use 12 gauge cables and the Zamp supposedly has 10. (Smaller gauge=bigger wire). So that's all good. You want the cables to link directly to the battery. Here's all I did on my old rig.


I pulled the drawers and inspected the wiring underneath. It looks like all the DC wiring is 12 gauge it's hard to tell, don't know how thick the insulation is. Not sure I want the solar panel connector on the canopy side. If I buy a portable system I guess I need to mount some kind of quick connect on the utility side and hook it directly to the batteries.
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Old 04-07-2017, 07:25 AM   #23
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Typical panel to controller voltage drop design is for 3 percent or less. My SC-2030 can be located anywhere along the wire run, possibly reducing requirement, while it compensates for loss from it to batteries, not all controllers can do this. Fuse size and wire gauge to existing lights / devices has nothing to do with a solar/ install. I calculated using 9.25A per panel (Renogy 150W) and typical 21 VDC in full sun and the wire run length to each panel. I needed to run #4 from combiner controller to stay below 3 percent.
My Renogy panels have #10 wiring.
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Old 04-07-2017, 07:48 AM   #24
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Right, what he said. I was a little worried when you talked about the downstream fuses. That's separate. Directly to the battery, do not pass Go.
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Old 04-07-2017, 12:29 PM   #25
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WolfWhistle Wow, your panels must be a long way from the SC2030. At 30 amps (which is the max it will handle), #8 doesn't drop 3% until the SC2030 is 13-1/2 feet away from the combiner box, and at that, it would only drop 1/2 volt at the max power point of your panels (something like 30 amps at 17 volts.) However, panel to controller feeds are a special case when employing PWM, which the 2030 does. At that max power point, the controller still has to throw away at least 2 to 2 -1/2 volts anyway, even if it was working the batteries in boost mode, in order to get to 14.5 volts at the bank. That .5 volts would still leave a lot of extra voltage for it to overcome the drop in the controller to battery circuit.

Sure this is only in max sunlight, but so is the 30 amps! #8 should have been fine anyway, even with 30 feet to the controller. The #4 only saves .3 volts anyway.

Never hurts to over spec though.
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Old 04-09-2017, 06:47 PM   #26
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WolfWhistle Wow, your panels must be a long way from the SC2030. At 30 amps (which is the max it will handle), #8 doesn't drop 3% until the SC2030 is 13-1/2 feet away from the combiner box, and at that, it would only drop 1/2 volt at the max power point of your panels (something like 30 amps at 17 volts.) However, panel to controller feeds are a special case when employing PWM, which the 2030 does. At that max power point, the controller still has to throw away at least 2 to 2 -1/2 volts anyway, even if it was working the batteries in boost mode, in order to get to 14.5 volts at the bank. That .5 volts would still leave a lot of extra voltage for it to overcome the drop in the controller to battery circuit.

Sure this is only in max sunlight, but so is the 30 amps! #8 should have been fine anyway, even with 30 feet to the controller. The #4 only saves .3 volts anyway.

Never hurts to over spec though.
I struggled with that Scott. The further-most panel is 17/18 feet to the combiner box in the pantry cabinet.... then all three panels run on #4awg about 16/17 feet to the 2030 (via 30 amp DC breaker)... controller is 2 feet to the + buss, which is then 5 feet on #4/0 to the batteries.

As I understand it, I could have located the 2030 where the combiner is and ran smaller gauge wiring to the + buss; letting the 2030 compensate for the loss / drop.

The most amperage I have seen in full sunlight with thirsty batteries is nearing 28 Amps (21volt input and 14.6v out). Panels are mounted flat but could be angled.

If using #4 combiner to controller isn't crazy enough, I spiced the longest 2 runs to the panel's #10 to #6 for about 8 feet. I think if I erred, which I probably did, I erred on the side of expensive.
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Old 04-09-2017, 08:23 PM   #27
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Curious as to how you can get 20 volts from 12 volt panels in parallel that are operating near their mpps. Would expect it to be closer to 17 or 18. Somebody isn't getting loaded down, but you do have 28 amps...

28 amps at 20 volts is a lot of power...like 560 watts!
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Old 04-09-2017, 08:41 PM   #28
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If if add that up it sounds like around 68 feet round trip, 21 volts at 28 amps. Looks like you could have done it all with one #10 feed, since you would still have 19 volts for the SC2030 to cut down to 14.4 or so.
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Old 04-10-2017, 03:07 PM   #29
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I know I read 21 volts, but what was the amps? I can't recall. So I am curious as well. I think I replied to a solar post, but can't find it. So, right now with one panel severely shaded (nearly zero output) The batteries status 95%; I read 14.31 input and 14.18 out... at 8 amps (system total). So, I climb on the roof and clean off a bit of pollen accumulation; then I get 14.85 in, 14.4 out @ 12 amps. No clouds in the sky. When I was attempting to calculate voltage drop and pick wire gauge, I am pretty sure I was using 12 volt and 9 amps for each panel.
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