Reply
 
Thread Tools Display Modes
 
Old 09-14-2017, 08:55 PM   #1
Skoolie
 
T-Bolt's Avatar
 
Join Date: Jun 2016
Location: Lafayette, Indiana
Posts: 188
Year: 2003
Engine: DT530
Rated Cap: 84
Future solar conduit

I will probably have my interior finished before I get around to doing solar. I would like to run a conduit from my roof to the basement for future use. Does anyone know what size conduit I should run for a solar system up to 2,000 Watts?

Sent from my SAMSUNG-SM-G930A using Tapatalk
T-Bolt is offline   Reply With Quote
Old 09-15-2017, 12:42 AM   #2
Bus Nut
 
Join Date: Jun 2016
Location: Orange County, CA
Posts: 860
Year: 1990
Coachwork: integral
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
I have 2040W of panels in two separate individually-tiltable arrays on either side of a central walkway between my two roof hatches. Each array of four panels has its own fused combiner box, from where 4AWG positive and negative cables run through the roof ribs down to the 50A breakers and charge controllers under the floor. Because each array is wired in parallel, their Isc is about 34 amps, so 4AWG welding cable will cause negligible voltage loss. I use aluminum weather-tight Bell boxes bolted to the roof under the walkway that each contain four 12A fuses and two busbars for pos and neg, and the 4AWG cables run from there without interruption to the breakers and charge controllers. Getting the cables from the lower ends of the roof ribs down to and through the floor was a challenge, but I now have continuous conduit to allow easy cable replacement if ever needed.

Don't use too small a cable for any low-voltage high-current applications. If in doubt, go larger! And use a proper circumferential crimper to attach the cable lugs - cheapo hammer-type crimpers are not enough!

John
Iceni John is offline   Reply With Quote
Old 09-15-2017, 11:59 AM   #3
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 5,627
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Using John's example, with 4 x #4AWG conductors would require a minimum of 1" conduit.

I would suggest that you go a bit larger to accommodate future needs.

Google "conduit fill calculator" and you will find resources that will explain how to determine conduit sizing.
PNW_Steve is offline   Reply With Quote
Old 09-15-2017, 03:09 PM   #4
Bus Crazy
 
Join Date: Jun 2013
Location: Picton,Ont, Can.
Posts: 1,773
Year: 1997
Coachwork: Bluebird
Chassis: GMC
Engine: Cat 3116
Rated Cap: 72
Can you describe the route from the roof to the basement, totally outside the passenger compartment or going inside as well?
Going bigger in conduit size isn't a lot more money in any event. Bigger pipe makes for better and stronger attachment of supports and straps.
I'd go minimum 2" with suitable weatherproof fittings.

John
__________________
Question everything!
BlackJohn is offline   Reply With Quote
Old 09-15-2017, 05:36 PM   #5
Site Team
 
JDOnTheGo's Avatar
 
Join Date: Feb 2017
Location: The West
Posts: 1,001
Year: 1998
Coachwork: MCI
Chassis: 102 EL3
Engine: DD 60
Quote:
Originally Posted by T-Bolt View Post
Does anyone know what size conduit I should run for a solar system up to 2,000 Watts?
I admire planning! I am here to complicate it!!!

If you run high voltage panels, you can use much smaller cable (and an MPPT charge controller). I'm living on 1700 watts running down #10 cable at 60 volts. This doesn't sound like a big deal until you start pricing those big thick copper cables - then you might become interested.
__________________
JD - Full timer out west
Missy - 1998 MCI 102-EL3 - 1.7kW Solar - 10kWh Lithium
My Adventures & Build
JDOnTheGo is offline   Reply With Quote
Old 09-15-2017, 06:57 PM   #6
Bus Nut
 
Join Date: Jun 2016
Location: Orange County, CA
Posts: 860
Year: 1990
Coachwork: integral
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Sorry, I forgot to say that I run the two 4AWG pos cables down one side of roof ribs, and the two negs down the other side. This way I can easily fit two cables per rib, and there's no risk of pos and neg being too close to each other inside the combiner boxes. Two 4AWG cables fit very nicely inside a roof rib.

John
Iceni John is offline   Reply With Quote
Old 09-16-2017, 12:24 AM   #7
Bus Nut
 
Join Date: Jun 2016
Location: Orange County, CA
Posts: 860
Year: 1990
Coachwork: integral
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Quote:
Originally Posted by BlackJohn View Post
Can you describe the route from the roof to the basement, totally outside the passenger compartment or going inside as well?
Going bigger in conduit size isn't a lot more money in any event. Bigger pipe makes for better and stronger attachment of supports and straps.
I'd go minimum 2" with suitable weatherproof fittings.

John
I've covered over two windows on each side, and my solar cables and PEX water lines run through them. Crown's construction is very different to other buses', which made it a challenge to put the cables where I wanted. The roof ribs end at longitudinal structural beams above all the windows, and the bodyside ribs start at these beams and extend down to the bottom of the bodyside. This means that I had to bore 1" holes through the beams' 3/8"-thick 90,000 PSI steel to make continuous runs for the cables and PEX, then run them inside the polyiso insulation between the blanked-off windows' inner paneling and outer skin, then through the window sills and down about one foot inside Crown's Dry Wall side walls before coming back through to the inside, then through the chair rails, than back inside the walls to go down through another massive steel stringer that connects the bodyside and floor, and finally for them to resurface inside the underfloor luggage bay where the breakers and charge controllers live. It sounds complicated, and it is! However, the cables and PEX lines are completely protected and out of sight, yet can be replaced if needed without (I hope) too much drama.

And if you're wondering about my mention of PEX water lines, I have a cold water line running up to the roof to feed two quick-connect outlets on the walkway for a washdown hose and brush - this makes cleaning the solar panels easy and safe. Instead of dragging hoses or heavy buckets of water up to the roof, I just open the front roof hatch, climb up through it onto the roof's central walkway, plug in my washdown brush and in a few minutes all my panels are squeaky clean. I also have another cold line running up to the roof and a hot return line coming back down from the roof, both of them for my eventual solar water heating panels that will occupy the last few feet of space after the last PV panels. These water panels will also be hinged to the walkway like my PV panels are, then they can be tilted up to 45 degrees above horizontal for better performance in the winter when the sun is lower.

Yes, it's been a lot of work to make everything this way, but I feel it's the best possible way for my needs. I'm only doing this once, so I'll do it the best way I can.

John
Iceni John is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:07 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×