Success finding the Solar pre-wire on the roof!

[Peter C]

After a long ordeal I finally been able to find the factory solar pre-wire and terminate it at the roof! I first asked the dealership to find and terminate it for me when they were replacing the skylight. The pre-wire was not in the rear fantastic fan like it’s supposed to be so I’d ask them to locate it when they had the skylight out. I gave them wire and the rooftop gland. They told me they couldn’t find it (didn’t want my money I guess).

The pre-wire was definitely at the front DC distribution area and all my research said that it should be in between the skylight and the rear fantastic fan. I purchased an inexpensive electrical toner and could confirm that the pre-wire was close to the area of the fan. It was difficult to find out exactly where it went due to the toner not working well through the aluminum skin.

Today I got out the drill and punched a hole through the roof…success! The hole was it within an inch of where the wire was located. I’m so happy and now I can start installing the panels.

And I’m now kicking back and celebrating with a G&T.

[Peter C]

Here are a few pictures



[ATTACH]404396[/ATTACH]

[uncle_bob]

Hi

I'd go with a box that fans out to at least 4 panels on a new install ....

Bob

[Peter C]

Originally Posted by uncle_bob

Hi

I'd go with a box that fans out to at least 4 panels on a new install ....

Bob

Yes I considered a junction box and definitely would have gone that way if I ran heavier gauge wire to the controller.

I do have four Renogy Eclipse 100 watt panels that I hope to install this week. I am planning configure a 2 and 2 parallel - series. With using the 10 awg factory pre-wire I am concerned about too much amperage if I go 100% parallel. My controller would take all four in series but then I would take a big hit with any shading.

We camp in the mountains/foothills the majority of the time so solar is often not that effective when boondocking. I end up running the generator for 30 to 45 minutes each day to top things up.

Thanks,
Peter

[uncle_bob]

Originally Posted by Peter C

Yes I considered a junction box and definitely would have gone that way if I ran heavier gauge wire to the controller.

I do have four Renogy Eclipse 100 watt panels that I hope to install this week. I am planning configure a 2 and 2 parallel - series. With using the 10 awg factory pre-wire I am concerned about too much amperage if I go 100% parallel. My controller would take all four in series but then I would take a big hit with any shading.

We camp in the mountains/foothills the majority of the time so solar is often not that effective when boondocking. I end up running the generator for 30 to 45 minutes each day to top things up.

Thanks,
Peter

Hi

The 10 gauge wire is fine for four panels and still would work for six. That assumes you run them in parallel. If you do a series / parallel setup ( 6 done as 3 strings of 2 each or 2 strings of 3 each ...) you could put a *lot* of solar up there. Yes, there's a bunch of math to back that all up.

Bob

[Peter C]

Thanks Bob,


I was thinking that at approx 20V and 25ish amps (four panels in parallel) there would be over 5% loss on the 10 AWG. I am using the assumption of 35 to 40 feet of wire from the roof to the front DC distribution area (27FB)).

You think that Parallel would be fine at that length? I did trace the wire using the toner so I could run a string to confirm length.


Peter

[uncle_bob]

Originally Posted by Peter C

Thanks Bob,


I was thinking that at approx 20V and 25ish amps (four panels in parallel) there would be over 5% loss on the 10 AWG. I am using the assumption of 35 to 40 feet of wire from the roof to the front DC distribution area (27FB)).

You think that Parallel would be fine at that length? I did trace the wire using the toner so I could run a string to confirm length.


Peter

Hi

40 feet of wire from the normal junction box to the normal DC bus area is a mighty long run. If you are talking about a 40 foot loop then sure.

10 gauge is a mili ohm per foot. A 40 foot loop is 0.04 ohms at 25A that comes out to 1V. 1V out of 20 is indeed 5%.


Bob

[Gene]

When Lewster mounted two 100 w. panels on my roof he told me the factory 10 AWG wire was undersized and ran another cable through the fridge area. Since Lew has an MS in electrical engineering, I believed him.

[dznf0g]

Originally Posted by Gene

When Lewster mounted two 100 w. panels on my roof he told me the factory 10 AWG wire was undersized and ran another cable through the fridge area. Since Lew has an MS in electrical engineering, I believed him.

Yup, per Lews posts back in the day, I ran 6 gauge marine stranded from the roof to the controller. Even though I only presently have 200 watts on the roof.

[uncle_bob]

Originally Posted by Gene

When Lewster mounted two 100 w. panels on my roof he told me the factory 10 AWG wire was undersized and ran another cable through the fridge area. Since Lew has an MS in electrical engineering, I believed him.

Hi

Well, there are others around here who also have that same degree ... the math isn't very hard. I've gone through it *many* times in these threads ....

Bob

[dznf0g]

Originally Posted by uncle_bob

Hi

Well, there are others around here who also have that same degree ... the math isn't very hard. I've gone through it *many* times in these threads ....

Bob

That's true, and I did too. I wanted to "future proof" the wiring and I prefer a parallel system for my needs and lifestyle. Running the wiring to the roof is a chore. Once and done.

But 10 gauge was simply too small.