Solar panel installation wiring

[andyvh1959]

I'll be shingling the roof on my new detached garage next week. In the plans I'll mount four solar panels on the south facing hip, and I'll need to route the solar panel wires through the roof into the garage. I have seen pictures of the wiring and roof enclosure, just wondering if anyone here has done it, what you used, what would you use, etc. I'd position the roof enclosure so it is underneath one of the panels rather than showing on the roof like shown here.

 

[nadogail]

IMHO, Your junction box wants and very possibly needs to be accessible with your panels in place.
If no other reason than solar system trouble shooting.

 

[Git]

It makes sense to locate the junction box where it is accessible.

Here is what my installers did. Junction box at the end of a row of panels where it is easily accessible, but the actual roof penetrations are a couple of feet over, under the panels. And before the "I would never install solar panels on my roof " people weigh-in, you know who you are , Going on 4 years now and ZERO problems

I have 39 panels on 2 roofs with all the conduit running through the attic. The wiring from the South roof runs over to the West roof and then all the connections are made in the junction box go back into the attic and down to the inverter by the main panel

 

[andyvh1959]

Thanks for the input. I'll plan to locate the "flashing box" (don't know what else to call it) near the west end of the panel array. Close enough to be serviceable but not far out enough to stand out on its own. I have seen two cable flashing boxes for RV roof applications but not so far for a shingled roof. I did find one NEMA 3R enclosure, but $125 for a plastic box to sit on the roof? I'll have just two cables going through the roof toe the Combiner box in the garage, then from the combiner box to the charge controller.

 

[andyvh1959]

I am planning the wiring for the combiner box, charge controller and junction box. I plan to use plastic conduit to contain the cables from the solar panels to the combiner box. The junction box will connect the combiner box to the charge controller, and allow access to the connections. Output of the charge controller will go to the batteries, and output from the batteries go to the circuits. Just realized I need to add a ground rod outside the back for the solar system.

I have four 220w panels, just have to decide if I run them in parallel or series to the charge controller. I feel I might be better off to connect two panels in series, and those two in parallel to the the other pair for 24v to the charge controller. Or am I better off to connect all four panels in series for 48v to the charge controller? The output of the charge controller to the batteries will be 12v nominal. So now I'm shopping for at least two batteries for the 12v circuits. I'm thinking deep cycle AGM batteries. Comments? Thoughts?

 

[MBfreak]

From a cable loss and cost point of view it is wise to run all the panels in series, thereby reducing the current from the sunfarm to the inverter.
Since the watt losses in the cable connection is resistance in Ohms times load current squared , you will need 4 times the area in the cable if you run two parts in //

Ola

 

[laser3kw]

And before the "I would never install solar panels on my roof " people weigh-in, you know who you are , Going on 4 years now and ZERO problems

(que Albert Hammond)... but it never rains in southern California ...

 

[Brandon_oma#692]

Do you have a charge controller yet? What voltage will it accept?

 

[WisJim]

The advantage of series connection of the panels is less voltage drop and therefore less power loss in the wiring. The disadvantage is the excessive power loss from all the series connected panels if even one of them is even slightly shaded. So to me it would depend on how much shading the panels get