Adventures in going solar! - Montana Owners Club

WaltBennett · 05-29-2014, 08:55 AM

Pretty much decided on and bought panels, charge controller, cabling and misc. hardware after figuring out how it should be wired. Went with four 100w, 12v panels so I can put them more places. Since I wanted smaller sized panels, I don't need MPPT and the charge controller was only $190 shipped, with remote temp. sensor. Tried getting quotes from two local installers, but decided to do this myself as one said they always went through the refer vent (it's on a slide!) and the other wasn't willing to put in 4 gauge wire.

Was able to get THHN wire, combiner & entry box, plastic flex conduit & fittings and all the misc. at the local Lowe's. Couple tubes of Dicor from a local RV place. The big parts came from internet stores. So far an easy project!

Actually finding a good way to route the two cables from the roof turned out to be a bit of work. I suspected that there was space behind the rounded corner in the bedroom, so I cut a panel out under the sink as carefully as I could. Not that easy as it had about twenty brad nails and another dozen staples holding it in. Was able to salvage the trim and will put it all back together after the install is completed. May even add a shelf which will hide the horizontal cut completely. Got all this done and was able to see that there's clear space all the way to the roof. You can see that I'll have to get the solar feeds to the basement in front of the water & drain lines as the furnace duct is alongside. Total run to the charge controller should be under 16'.

http://s1354.photobucket.com/user/th...20-%20Part%201

Yesterday the panels arrived between rain storms. Today it's raining off and on all day, so I'm putting this up now. Did get a chance to check out a local Trojan battery place. Price is a bit more than I'd like, but then this isn't Arizona. They had T105s and separate battery boxes for them although I'll have to rig a combined venting system.

UPDATE - Stopped raining this AM. Started by taking off the two MaxAir vent enclosures that would have shaded at least one panel. Found one vent cover falling apart at a touch - off to the RV parts place again. Rest of the day spent installing two new vent covers and cleaning the roof & marking joist locations. For those hard core MPPT folks - sorry, but I don't think the almost three times cost is worth the small benefit in this particular system. 400 watts to four batteries via a TriStar TS-45 will do all we need and can still add more panels. If I wanted to live off-grid for days on end, then I'd go a different direction. THHN 4 gauge wire was only $10 more than 6 gauge for 40' - why not?

twindman · 05-29-2014, 01:58 PM

I am sure you did much research on solar before starting a project like this. In case this may provide additional info for you, here is a link to a guy that talks about everything. I didn't re-read the whole thing, but one article I read said the installers mostly don't know what they are doing. Wire size and distance between things if hugely important. So here is the link.
http://www.jackdanmayer.com/rv_electrical_and_solar.htm
(You may have to cut and paste it) Oh, the section on 'Why many systems don't work well' discusses the wiring.
p.s. I decided I didn't boondock enough to warrant the expense....

WaltBennett · 05-29-2014, 03:02 PM

Yes, I've read his as well as a lot of others. All of them (after some get done selling what they want to) come down to saying put in the largest size wire you can. What I can't understand is why solar installers refuse to do this. All I was asking is for someone to put the panels on the roof where I asked and to run 4 gauge down to the charge controller. Sounds reasonable to me, but guess I'm just stupid (according to them).

Bigboomer · 05-29-2014, 03:19 PM

Walt,

Here is the problem, most installers are both lazy cheap. The heavier the wire the more difficult it is to work with. It takes more time to feed the wire, more time to run connections and costs more.

The heavier the wire the less the resistence thus the more efficient the system will be and perform better. For the few extra bucks it will be well worth ovet the long haul.

7.3Ford · 05-29-2014, 04:05 PM

Walt,

I think for four 100 Watt panels, 8 gauge or 6 gauge would have been fine for 12 volts panels in parallel. Using 4 gauge will give you room to add more panels up there.

I went with MPPT, and run around 70-80 volts down from the panels to the controller with 10 gauge wire. From the Controller to batteries is 2/0 AWG stranded copper wire (from welding supply)

7.3Ford · 05-29-2014, 04:18 PM

Quote:

quote:Originally posted by Bigboomer

Walt,

Here is the problem, most installers are both lazy cheap. The heavier the wire the more difficult it is to work with. It takes more time to feed the wire, more time to run connections and costs more.

The heavier the wire the less the resistence thus the more efficient the system will be and perform better. For the few extra bucks it will be well worth ovet the long haul.

Les,

If efficiency is what you want, you are better to put the money in a MPPT control. A MPPT controller allow the panels to operate at the peak voltage where you get full rated power. With a non-MPPT controller, the voltage of the panels is tied to little above the voltage that the batteries currently are at. Most 12 volt panels put out peak power around 14-15 volts, lets say your batteries are down to 11.5 volts, voltage on the panels will be a little about 11.5 volts. This is why a MPPT controller will give you 20-30% more output than non-MPPT controller. With MPPT controller, the voltage from the panels is adjusted for the panels to product the maximum output, and the output is adjusted for the voltage the batteries want.

Bigboomer · 05-30-2014, 01:05 AM

John,

Yes, certainly agree that the MPPT is the way to go but just looking at Walt's setup where he did not go with the MPPT is why I noted the heavier wire and yes 4 gauge is certainly overkill but that should not be the reason an installer would not work with it.

Your point is on the mark in that spending the money up front on the MPPT for a couple hundred more in lieu of the heavier gauge wire would certainly be the better trade off.

**DQDick** · 05-30-2014, 03:08 AM

All of the above is the reason I went with a quality install team and paid them to do it. It is possible to use the heavy wire and get a great looking install. We threw them a bit of a curve in what we wanted our system to do so in my case it took two guys who do it every day at Q a full day and part of the next morning to get it looking great and working to my satisfaction. Take your time and work slowly and you'll have a great installation. Good luck.

**DQDick** · 05-30-2014, 03:41 AM

All of the above is the reason I went with a quality install team and paid them to do it. It is possible to use the heavy wire and get a great looking install. We threw them a bit of a curve in what we wanted our system to do so in my case it took two guys who do it every day at Q a full day and part of the next morning to get it looking great and working to my satisfaction. Take your time and work slowly and you'll have a great installation. Good luck.

WaltBennett · 05-31-2014, 10:11 AM

Spent most of today working on the Monty and actually got some stuff done (for a change!). Had some slight issues drilling through the roof as there was a joist partially blocking where I wanted to go. Everything worked out OK, although the pull box isn't 'squared away' (old military thing I'm still trying to get rid of). I can understand why the one installer didn't want to use 4 gauge as it does take some time to work it through things. THHN isn't very large in diameter though, so I didn't have to open up any huge holes. Got the panels mounted where I wanted them - all to the front, but not blocked by anything. We've never used the bedroom vent, but I wanted that panel far enough away that if we got a second AC it wouldn't kill the panel. The others are still on the high roof part and there's lots of room from more if we ever decide to add. The combiner box is sitting close to where I'll mount it. Going to work on the basement and forward bulkhead tomorrow, mounting and cabling the solar panel disconnect box and charge controller.

http://s1354.photobucket.com/user/th...20-%20Part%202

7.3Ford · 05-31-2014, 06:01 PM

Walt,

Installation looking good so far.

WaltBennett · 06-01-2014, 09:34 AM

Finished basement & front compartment cabling, mounted TriStar and disconnect box. Left several cables longer than needed since I still just have the two 12v batteries that came with the trailer. Decided I'm going to wait until tomorrow AM to mount the combiner box and hook up the panels. My back & knees can use a day off!

UPDATE: Going to be more than one day off. Found I was shorted an MC4 connector set in my shipment and can't connect all four panels. Vendor is sending another, but it'll be a few days. Probably start raining then!

WaltBennett · 06-10-2014, 07:21 AM

Received the connectors & completed all I can to the combiner box until we get a few days of dry weather. This whole week is supposed to be off & on rain though. Put the access panel back under the bath sink & cleaned everything up. Just waiting now . . .

http://s1354.photobucket.com/user/th...20-%20Part%203

WaltBennett · 06-17-2014, 03:19 AM

Finally got back to working on it all, but spent two days troubleshooting a short - I put two screws through the holes in the buss bars to make certain they'd stay in place. Great idea save for the roof insulation foil! Shorted both busses to each other. I'd already epoxied them to the box, so that will have to do. Everything works now & the TS-45 is doing it's thing to the old 12v batteries. Next step is to pick up four T-105s. Can't figure out why individual boxes are only $10 - $20 each and a double isn't less than $80. After the batteries comes a big inverter.

**DQDick** · 06-17-2014, 03:38 AM

Glad to hear the project is moving right along. Bet you'll be glad when it's all done.

7.3Ford · 06-18-2014, 12:24 PM

Walt,

One thing when you connect multiply batteries, make sure you take the feed lines to the Montana off of opposite ends. Otherwise the batteries will not be used evenly. John Hohl told me about that, and I had to re-wire mine. Here is a picture from Trojan Battery booklet.

WaltBennett · 06-22-2014, 01:05 AM

Thanks, John. That much I'd already known about. I had to rewire the two 12v batteries that came with it after buying it last year. The totally NOT knowledgeable dealer had wired the second with 8 gauge to the first which had 4, just adding it on. I'm going to have the drawing rotated counterclockwise with 2 gauge feeds & 4 gauge battery connectors. Working the electrical resistance numbers tells me this will work just as good as all 2 gauge and be a lot easier to make.

WaltBennett · 07-10-2014, 01:15 PM

FINALLY got the inverter w/remote installed & working. Had a weeks junket to upstate NY and a few other things keeping me from doing much until last week. I had wanted to get the battery bank first, but came across a to-good-to-pass-up deal on eBay. 3kw AIMS pure sine wave (has a built in MPPT solar charger too) and a remote for same for under $700. If it works for five years I'll be a happy camper! Spent two days figuring out what circuit was on which leg when two 'pair' had been mislabeled. Rest of the time was taking panels off & running cables. Thinking about rewiring the refrigerator (it's on "Kitchen 2" along with one outlet) after finding out that it'll draw 30 amps of DC to make whatever AC amps it uses. Just forgetting to switch it to propane one time could make a dent in the batteries before being noticed. I was able to get four battery boxes from Amazon (Trojan T105 size) for under $100 - only problem is coming up with a decent venting system. Although I bought them all at the same time to get free shipping, Amazon sent them individually, arriving each on a different day - strange!

Bigboomer · 07-10-2014, 01:35 PM

Walt,

May I suggest using pvc piping to make a connected venting system for your batteries using the existing hose to the exterior.

Good luck,

Les

WaltBennett · 07-11-2014, 01:40 PM

That's what I'm doing Les. I'm trying to work out something that'll come apart easily to check water levels, but still stay together while going down the road. Got something figured out (I think), but I'll have to pull the old batteries & boxes out & put the new ones in to really be certain. We're supposed to be getting a polar vortex next week (believe it or not!) and temps will be 10 - 20 degrees cooler from the 85 to 95 that's been the norm for too long now. Think I'll go get the new batteries then & put them in.

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