Solar panel advice needed - Montana Owners Club

WorkerB · 10-12-2009, 06:08 AM

I have been working toward getting solar panels. I'm looking for pros and cons of roof vs. ground mount solar panels. It looks like most folks go with roof mounted panels but I have seen others that have ground mounted panels. If I go with roof mount I am limited in size where if I go with ground mount I can go with fewer larger higher output panels. My big concern with ground mount of course is theft and vandalism. Rather than reinvent the wheel I figured I'd go to the subject matter experts! I am pretty comfortable with how I would mount roof panels but any ideas for ground mounting would be appreciated.
Thanks,
John

sreigle · 10-12-2009, 10:37 AM

John, Robbie Simons (simonsrf) has a full solar array on his rig. He and Alice spend the majority of their fulltime life boondocking in some gorgeous sites. If you can locate his membership on the members page you might consider emailing him for his suggestions and experiences.

If I recall, some time last year Robbie told me they'd spent one night in a real rv park in the prior three months. Something like that.

WorkerB · 10-12-2009, 03:49 PM

Hi Steve,
Actually, that was my first thought. The last time I saw Robbie he said he was getting a little tired of so many trips up to the roof to reposition his panels. I'm looking forward to hearing how people store and transport ground mounted solar panels. I saw lots of people last year at Quartzsite that had solar panels out and not on the roof. They were not in our group. If I remember correctly we did have one MOCer in our group Charlie 8.1al had a ground mounted system. I don't think he had issues with wind.
See Ya,
John

bigmurf · 10-12-2009, 04:33 PM

I used a ground system for two 80 watt panels. Got tired of storing them and put them on the roof along with two more 120 watt panels. I don't tilt the panels. If I need more output I will just add more panels. There is a lot more room on the roof if needed.

**Carl n Susan** · 10-12-2009, 05:54 PM

John: I am pretty sure it was Crossthread (Bill N.) that had the ground mounted (is that a real term?) solar panels. He got it at Costco and I think it was intended to just re-charge his batteries. Charlie didn't have solar AFAIK.

WorkerB · 10-12-2009, 06:39 PM

Carl,
If you are sure it was Bill, I stand corrected. I believe he had 3ea. 15 watt solar panels. I didn't notice if they just sat on the ground or were staked so they couldn't blow over in the wind. I also plan on charging my batteries but I'm curious if folks reposition their panels several times a day for best power production. If that is the case is there hardware built in to the framework that allows the panels to move or does the whole array have to be moved and re-staked to the ground?

ols1932 · 10-12-2009, 11:00 PM

Quote:

quote:Originally posted by WorkerB

Hi Steve,
Actually, that was my first thought. The last time I saw Robbie he said he was getting a little tired of so many trips up to the roof to reposition his panels. I'm looking forward to hearing how people store and transport ground mounted solar panels. I saw lots of people last year at Quartzsite that had solar panels out and not on the roof. They were not in our group. If I remember correctly we did have one MOCer in our group Charlie 8.1al had a ground mounted system. I don't think he had issues with wind.
See Ya,
John

We have the roof-mounted solar panels--four of them, each one 125 watts. We never go up on the roof and reorient them, just leave them flat. Have had them six years now and they've worked fine. I personally would not want to haul aroung a ground type array and have to keep setting it up.

Orv

gojodo · 10-13-2009, 02:48 AM

We have four roof mounted panels and leave them flat as well as others, except when using them in the far North, like Quebec this year. The reason I prefer the roof mount is because my batteries are being charged while driving down the road. As to which is better I would say the ground mount only becomes an advantage when you want to park for a long time under trees and you are not traveling much, pretty much stationary.

gojodo · 10-13-2009, 02:53 AM

By the way we have four AM Solar Panels rated at 100 watts at 2l.5 Volts with 44cells, much higher than most panels. These provide adequate power to run everything except my air conditioner in clear skys.

simonsrf · 10-20-2009, 05:23 AM

John,
I had 4 solar panels when I USED to point them. I then bought 2 more for a total of 6, they are all roof mounted. With our usage in the winter time, we found we don't have to point them, we have enough electricity stored for our needs when we conserve.

These are AM Solar panels.

On the other hand, in winter, if I tilt them toward the south, we get an increased amount of power which is very convenient having an abundance of needed electricity.

Like at Quartzsite, where I know we will be there for an extended period, I tilt them and leave them that way for the entire time.

BTW, it was Bill (crossthread) who had the Costco solar panels. He only used them to trickle charge his batteries.

Sgrob47 · 10-22-2009, 05:40 AM

John ,
I'm like Robbie have 6 AM solar panels on roof, and 6 batteries for storage. I don't tilt my panels unless I'm going to stay in one place for 2 or 3 weeks, like Quartzsite. Don't really see a reason to tilt panels the gain I get is about 4 to 5 amps. I have so many batteries cause I run a chest freezer all the time on the inverter, plus like the option to watch TV and run my Hughes internet dish whenever I want. Also nice to know that batteries are charging while driving down the road. Since I'm also a fulltimer no place to store panels for ground use. I also have a Onan 5500 propane generator in case there is no sun for couple days. Might want to checkout www.amsolar.com they do sell a self install kit. See you in Quartzsite.

Steve, AKA 'Wonton Steve'

WorkerB · 11-03-2009, 03:41 PM

Well I guess the roof mount wins! I was really expecting some debate like which is better 3/4 or 1 ton. I guess it was not to be. So... I found solar panels that will work on the roof. 6 ea. 80 watts per panel. I'll pick em up tomorrow morning. Just had eye surgery this AM and doc says no lifting for a week. Now if the snow will just hold off till then so I can install them. Thanks all for the advice.
John S.

simonsrf · 11-04-2009, 03:52 AM

John,

The solar panels wires all comes to a single junction combiner box. I plan on having a cord built from that combiner box so that I can take the panels off the roof and be able to locate them in a different place if needed ....well, that project IS on my todo list...

NO heavy lifting!...need to save your strength for Quartzsite.

BTW, The Quartzsite Rally is only 73 days away...

jretz · 11-04-2009, 04:24 AM

John, remember to remind Roxanne to be careful when she loads the panels. Are you sure 6 panels will be enough power? You may have to add 2 or 4 more batteries. I was looking at my batteries and figured I could but 2 more behind the ones I have.

WorkerB · 11-04-2009, 03:01 PM

Robbie, Where are you going to relocate the combiner box? Down the fridge vent and inside the Monty? My book sez I can run #8 wire for about 25 feet from each panel to the combiner. #10 wire only goes about 16 feet. Should I reconsider moving my combiner box inside? What issues am I missing?

JRetz I'm afraid the weight police are going to get me. The panels are adding 120 more pounds. The new freezer is light BUT it's empty. Spec sheet sez 170 Lbs. when full. I need to bring wood to Q. For me, adding two more batteries are out of the question. I'm going to have to lighten up. Maybe I need a 1 ton! He, He, Sorry I couldn't help it!
See Ya,
John

simonsrf · 11-04-2009, 05:15 PM

John,

My combiner box is on the roof....just a central point that connects all of the panels together

I don't know enough about it to tell you what wire I'm going to use, or where it will be located...I leave that up to my good friends at AMSOLAR....they figure that sort of thing out, and I reward them with money.

bigmurf · 11-05-2009, 02:27 PM

My combiner is on the roof also. It is under the frig vent cover.

scattershot · 11-05-2009, 04:39 PM

Simonsrf, I see you subscribe to my method of home repairs and modifications. Write a check! Couldn't be simpler.

firetrucker · 11-05-2009, 08:31 PM

John, I found a wire size calculator that recommends 12 AWG wire for a 25 foot run (round trip) for a 3% voltage drop at 8 amps. That's a lot easier to handle, and cheaper, too, than 8 AWG, and you could probably use at least 14 AWG without serious loss, or 16 AWG if the length is 10 feet or less to the combiner.

WorkerB · 11-05-2009, 11:54 PM

Morning Bob,
I used a slightly different chart that calcs a 2% loss. I tested the panels and they averaged 4.3 Amps into a fully charged AGM Battery. I already bought double insulated #12 wire to run on the roof from the 6 panels to the combiner box on the roof. From the combiner box to the 30A Controller in the battery compartment I am running #6 AWG which BTW is the largest wire size the controller will accept. I have that wire on hand as well. I need to fabricate roof mounts for the panels. That is something I can do indoors as the weather is predicted to be nasty at least until Monday.
I'll keep you advised as I progress.
John

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