Solar combiner box

Calkidd wrote:

rocmoc wrote:
Spent under $20 at Home Depot. Used plastic outdoor electrical junction box with 4 in/outlets and two bus bars with associated items for waterproofing. After mounted on roof, waterproofed with Dicor Caulk and a final layer of alum tape to reflect sunight. I have 4 cables coming from two solar panel arrays entering in two in/outlets from the panels and one set of wires existing in a single in/outlet to the solar controller. Have another empty in/outlet for one more array of panels if needed or desired in future with plenty of room on the bus bars. 720 watts of solar. Looked like this with more in/outlets, http://www.freesunpower.com/project2.php

rocmoc n AZ/Fld/Baja

See post #2

Saw / read it before I posted and point is?

rocmoc n AZ/Fld/Baja

Colo Native wrote:

...
I was thinking if necessary I would run 6 or 8 but 10 is rated for 30 amps and my 2 panels are 18.5 amps

Total Imp on mine are about the same amps, and am running 44 ft (round trip) of #10. Charts I've seen say you can run #10 upto 50' at 20 amps without Ampacity (or overheating) issues. But you will incur significant voltage drop and losses at 20A. I calculate a Max 2.3% V drop for my system at peak current.

One of these days, I may replace the ~24' of #10 running inside the trailer (no UV) with something thicker and drop those losses. But since we rarely (if ever?) see peak current, I'm in no hurry. I put all those panels on the roof not for the bright summer sunny days, but for the grey wet days in Fall, Winter, Spring when there's no chance of peak output.

I was in the same dilemma. My inadequate over rated solar panels (sorry jab from another thread) will possibly produce 30 amps. 10 would work but I decided to run 8 GA. I bought 105 degree Celsius 8 GA cable rated for 90 amps. I think I am good now.

pigman1 wrote:

Colo Native wrote:
Should I run 10 awg wire from the box down to the controller or bigger can't find uv protected wire in larger sizes

That's why I ran my 2ga out the bottom of the box and down thru the roof to the basement behind the washer and drier. Putting the heavyweight cable in grey Corlon conduit and across the roof to a protected location is also an option. Ten gauge cable for more than one panel connected in parallel is just too light.

Interesting how some folks reject real world experience in place of their uninformed personal opinions. Your choice... I just reported what really worked.

I was thinking if necessary I would run 6 or 8 but 10 is rated for 30 amps and my 2 panels are 18.5 amps

2ga? Seems excessive. Are you running 200+ amps from your panels?

Colo Native wrote:
Should I run 10 awg wire from the box down to the controller or bigger can't find uv protected wire in larger sizes

That's why I ran my 2ga out the bottom of the box and down thru the roof to the basement behind the washer and drier. Putting the heavyweight cable in grey Corlon conduit and across the roof to a protected location is also an option. Ten gauge cable for more than one panel connected in parallel is just too light.

Interesting how some folks reject real world experience in place of their uninformed personal opinions. Your choice... I just reported what really worked.

Calkidd wrote:
I will have to agree the corrugated sleeve with harden and crack probably in one year time. I am not sure about the Eternabond tape. Once you put it down it's there for good. Heaven forbid you have to remove the solar or modify the wiring. You'll be stuck then. They make UV protected nylon cable clamps you can use.

Eternabond tape can be removed with a heat gun. Sticky, but not difficult.

To get at wires, just use a box cutter to splice the Eternabond tape. Just be careful.

Should I run 10 awg wire from the box down to the controller or bigger can't find uv protected wire in larger sizes

TechWriter wrote:

pigman1 wrote:
I've also covered it with common black split loom available at ACE or any electrical supplier or auto supply store.

I don't think that ACE stuff will last long.

I covered my solar wire with Eternabond tape.

I will have to agree the corrugated sleeve with harden and crack probably in one year time. I am not sure about the Eternabond tape. Once you put it down it's there for good. Heaven forbid you have to remove the solar or modify the wiring. You'll be stuck then. They make UV protected nylon cable clamps you can use.

rocmoc wrote:
Spent under $20 at Home Depot. Used plastic outdoor electrical junction box with 4 in/outlets and two bus bars with associated items for waterproofing. After mounted on roof, waterproofed with Dicor Caulk and a final layer of alum tape to reflect sunight. I have 4 cables coming from two solar panel arrays entering in two in/outlets from the panels and one set of wires existing in a single in/outlet to the solar controller. Have another empty in/outlet for one more array of panels if needed or desired in future with plenty of room on the bus bars. 720 watts of solar. Looked like this with more in/outlets, http://www.freesunpower.com/project2.php

rocmoc n AZ/Fld/Baja

See post #2