Conduit and PSPV

Discussion about the Power System PV Combiner (PSPV)

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sneaky

Conduit and PSPV

Post by sneaky » Thu Jul 06, 2006 10:55 am

Since the PSPV has only one 1" hole, does anyone have any advice on the number and size of conduit for the following scenario:

2/0 wire (one positive run, one negative run)
#6 grounding wire
power coming to Wattsun tracker

Is a 1" conduit enough for two 2/0 wire runs?

Do I need a separate peice of conduit for the AC power coming to the Wattsun tracker?

I assume I need a separate piece of conduit to run the grounding wire and this conduit needs to attach to the PSPV?

Finally, do I need to know the exact locatoin on the pole of the PSPV prior to getting the conduit in? Can the conduit be connected with a coupler if it is too short? The pole height out of ground is ~ 5.5'.

I wonder if the Wattsun power cable will get in the way of the PSPV. Does anyone have any ideas with this?

Sorry for the dumb questions, every PV installer I speak with has been hands off on the pole installation part. They're quick with list price quotes on equipment, but silent on some of the process. Therefore, any help from this board is tremendously apprecaited.

Thanks!

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Post by mvrck » Thu Jul 06, 2006 11:59 am

1" might not be big enough for 2/0... You should use a conduit hole punch to make the hole larger. You can get the hole punch from http://www.HarborFreight.com. See item 91201.

I used 1 1/4". I think you can go to 1 1/2" without getting too close to the 1/2" holes.

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sneaky

Post by sneaky » Thu Jul 06, 2006 1:33 pm

How does this tool work?

sneaky

Post by sneaky » Thu Jul 06, 2006 1:49 pm

Sorry, Mav. I found the answer on the harbor freight site.

Thanks for the tip!

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Post by sparky » Thu Jul 06, 2006 4:21 pm

A good quality hole saw works just fine. Pre drill 1/4" and then use the hole saw with the 1/4 " center bit.

Just finished my 3rd Wattsun and I would use the UL watertight and metal
(gopher tight) flexible conduit. The 1" will fit 3 # 4's or you could run 2 and bond to the metal in the conduit.

The Wattsun uses 24 V input to track 2 # 12's from the battery to the tracker is fine as it uses 20 watt hours per day. They sell voltage conversion boards but you should really think about 24 V battery minimum!

Sorry about the following posts how do you delete them?
Last edited by sparky on Thu Jul 06, 2006 4:35 pm, edited 2 times in total.

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Post by sparky » Thu Jul 06, 2006 4:22 pm

A good quality hole saw works just fine. Pre drill 1/4" and then use the hole saw with the 1/4 " center bit.

Just finished my 3rd Wattsun and I would use the UL watertight and metal
(gopher tight) flexible conduit. The 1" will fit 3 # 4's or you could run 2 and bond to the metal in the conduit.

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Post by sparky » Thu Jul 06, 2006 4:22 pm

how do you delete??????????
Last edited by sparky on Thu Jul 06, 2006 4:30 pm, edited 1 time in total.

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Post by sparky » Thu Jul 06, 2006 4:24 pm

A good quality hole saw works just fine. Pre drill 1/4" and then use the hole saw with the 1/4 " center bit.

Just finished my 3rd Wattsun and I would use the UL watertight and metal
(gopher tight) flexible conduit. The 1" will fit 3 # 4's or you could run 2 and bond to the metal in the conduit.

sneaky

Post by sneaky » Thu Jul 06, 2006 5:05 pm

Thanks, sparky. Redundant posts are okay by me. They make me reread everything more. :grin:

Well, providing the Wattsun tracker power issue is still unsolved in my mind. It is one I need to get my head wrapped around. The power center will be in the basement 130' away. I don't know if it is better to run DC or AC because of this.

Any advice you have is greatly appreciated.

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Post by sparky » Thu Jul 06, 2006 8:46 pm

I assume you will do all of this to code and since you are grid tied you will have to have it inspected.

Since I know you are 48V battery you have 2 choices. Buy the 48v system board from Wattsun or run from 24 volts of your 48 volt bank.
The 20 watt hours per day will not imbalance your system in any measurable way. It is also the most reliable as the 48 v board is yet one more piece of electrronics to fail.

I suppose you could run off AC but it definately would require seperate conduit and an ac/dc supply as the Wattsun is DC 1/12 HP

Remember you will need to know alot to make this fly with a building inspector ! or you could be very lucky and they'll just sign everything

Run the panels in groups of 5 at 60V ! It is very cool and I will respect you in the morning...................................................But if you have them already and can't get more........

The trackers can have a couple months backlog. Where are you located?

I have run # 10 150 feet for the 24v track motor. The drive circuit is designed for very high loss wiring or to run off small sunrise currents.
It is your solar output wire that you want less than 1.5 % loss.

sneaky

Post by sneaky » Thu Jul 06, 2006 10:46 pm

Indeed, there'll be inspections, hence the need to do it right the first time.

I already have 12 panels.

sneaky

Post by sneaky » Thu Jul 06, 2006 11:05 pm

Sorry for not giving all the answers, sparky. The tracker has been on order for six weeks or so. It is due any time.

I am getting the concrete poured on saturday, thus all of the questions with conduit sizing and grounding. I originally wanted to have a sign company do it, but they all wanted $2500, and suggested a very shallow hole (4') w/o any rebar reinforcement. I felt kind of skeptical and priced it out at much less doing it myself. I know how to work concrete so that is not such a big deal. It is all of the little parts and such relating to the PV wiring, breaker boxes, etc., that I need some guidance on.

Anyway, my goals are not to hack this, so I can take my time and do it correctly. But I am inexpierenced enough to know when and where to ask for help or clarification and I VERY MUCH appreciate the kind help people have offered on the Outback forum. :cool:

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Post by Kent Osterberg » Fri Jul 07, 2006 2:23 pm

Sneaky,

You can increase the KO on the bottom of the PSPV to 1.5" without much trouble. However 1.25" is sufficient for almost any installation. 1.25" conduit will handle 2/0 wire. You'd need a #4 ground wire with 2/0 conductors.

The lugs in the PSPV are only designed to accept wire sizes 1/0 or smaller so you might consider smaller wire. With 16 SQ 175 modules wired in 8 strings of 48-volts, I'd use #2 copper and a #6 ground wire. At the present price of copper, larger wire isn't giving you much for the extra investment.

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Post by sparky » Fri Jul 07, 2006 2:42 pm

Pouring cement on Saturday ! So Conduit will hold 2 # 2, 1 #6, And 2 #10s, You could just conduit the tracker location and tie in the 130" later with the snake you put in the tracker conduit.

You want that tracker to look real normal to an inspector so have the conduit come out of the cement up to the PSPV. Some want it to stand-off the pole a 1/2 inch or so but that can be finessed later. In your spare time a UFER ground in the cement as well as a few ground rods would be nice. Also a good time for code check electrical a 15 dollar book at Home Depot.

sneaky

Post by sneaky » Mon Jul 10, 2006 1:48 pm

Thanks again, sparky.

The pole is now fixed in concrete with three pieces of conduit neatly embedded in the concrete and running up the pole. It all looks really good and even better when I paint it.

Next weekend my tasks will be to string the cable, install the ground and mount the PSVP onto the pole.

Looks like #2 wire for the PV and #10 for the tracker. I have conduit installed for PV wire, tracker wire and ground.

Now this stage is completed, I have a new set of questions:

Can I use the same conduit for both the #2 and #10 wire?
Anybody have any cable pulling techniques to share? I have ~ 130' to pull.

Thanks again for everyon's help. I'll post pictures if anyone in interested in seeing the progress.

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Post by sparky » Mon Jul 10, 2006 6:38 pm

Sure run the DC cables altogether. At 130 feet you will need lots of soap.
A wire snake is one way but if you are frugal you could use a union on the conduit and only have to pull 65' twice.

#2 can be a bear so make sure the conduit is big enough!

sneaky

Post by sneaky » Mon Jul 10, 2006 9:17 pm

Thanks sparky. I'll use 1.25" conduit. Do you think #2 and #10 will fit? I am okay to run #10 in its own 1" conduit since the conduit at the pole is there, however I could save money by not having to and use that conduit at the pole for future expansion.

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