I'm going with 6 175w panels, 60x30 inches, canted out to match the curve
of the roof, I'll be able to tilt them inward to match the sun (so, the
sunny side should normally have enough tilt to be ok, the other side will
need to be tilted in rather than out). I have a DC air conditioner, that
puts out about 9k btu and uses about 600w of 12v DC. We shall see how it
goes. I'm only going to go with 200Ah of batteries, as the power is for
running the AC, and I don't plan on having a TV (laptops and fans, mostly,
for usage).

On Wed, Aug 16, 2017 at 12:21 AM, John Phillips
wrote:

> 1How much solar can we mount on our GMC?
> If you really want to commit to solar, it is possible to mount from 6 to 8
> SolarWorld 350 XL mono solar panels (79x40 inches with mounting hardware).
> Mount the panels on rails just over the roof air conditioners. 8 x 350 =
> 3600 yaaa but if you get 2500 watts from the charge controller, you will be
> doing really well. The other factors come into play are how much of it do
> you need now and how much do you need to store for later. A 2500 watt
> system should be able to generate 15,000-watt hours per good sunny day.
> How many days do you want to store?
> If you stay with 12 volts 15,000/12 = 1,250 usable amper hours per day.
> Lead acid batteries need to use 50% of name plate rating or less so you
> need 2500 AH/day using a 4 to 6-hour charge/discharge rate.
> If you plan on doing this with 6-volt CG2 golf cart batteries, 50 would be
> a possible number, two series groups of 25 in parallel. It 'd be good to
> use the 100-hour rate, but the peak Sun power does not last 20 to 100
> hours. If you are planning on a multi-day battery array maximum current
> does not have to be increased unless you plan on having a heavy discharge
> load. Now that the first-day current is taken care of the second day does
> not need another 50 batteries. I did not do the math but adding 30 more
> batteries should come close to a 2-day storage solution. Anyone for a
> trailer to carry the batteries?
> The battery sizing is based on storing all the power the maximum array can
> produce in a day. If you are using some of the power, you will not have
> enough energy to fully charge a dischared battery in a day. If you do not
> have enough battery, the charge controller will not harvest all the
> available energy. A lithium battery system becomes very attractive before
> we get to 80 CG2 batteries.
> By adding a soft start circuit to your air conditioner and using the solar
> array as well as some battery it is possible to run an air conditioner some
> of the time. An additional side effect is the solar cells act as a shade
> for RV roof. It is surprising how much cooler it is under a solar array
> than it is in the hot sun.
> As a side note, standard home roof and ground mount systems have to
> withstand 100 MPH wind gusts from the least favorable direction, and they
> are at an angle rather than flat.
>
> Disclosure:
> I designed and installed my home solar system using three different
> ratings of the SolarWorld XL mono panels. As time went on the panel ratings
> increased and the price decreased. The panel name plate ratings total 9180
> watts DC and the YC500A inverters name plate rating total 7000 watts. There
> are times the inverters cannot harvest all the energy the panels produce.
> Today my system generated 52590 Watt hours with a peak of 7150 watts at
> 2:01 PM. July's ouput was 1.6MWh, and I paid $1.05 for energy. I do not
> have any direct experience with charge controlers.
>
> On Tue, Aug 15, 2017 at 7:46 PM, Jim Kanomata
> wrote:
>
>> Solar is great when the weather is great. When the dark clouds stay
> around,
>> your not going to be singing the same tune.
>> We have installed 200 watt kits and found they are great only when
> weather
>> is good.
>> Always keep your generator as a stand by like the spare tire.
>>
>> On Tue, Aug 15, 2017 at 5:41 PM, Matt Colie
> wrote:
>>
>>> Ken,
>>>
>>> As usual, what you wrote is accurate - for the larger part.
>>> But,
>>> There is the case of the GMC 23s with the house bank in the front.
> Then,
>>> someone upsized the cables from the isolator and to ground as #4 AWG.
>> So,
>>> when departing from a weekend of dry camping (with the OE reefer) the
>>> alternator belt will squeal and get a surface glaze that makes it even
>> worse
>>> than it was.
>>>
>>> And I am thinking, "It is an old design 80 amp alternator, what is
> going
>>> on??"
>>>
>>> I got a new belt and reset the experiment at home. This time with a
> Bell
>>> current probe attached to a Fluke....
>>>
>>> Fire up!!
>>> What The ??
>>> Squeal !! 96 Amps out of the machine and all of 80 to the House Bank.?
>>> !Shut it Down.! Lets not do that again. That started the dual belt
>> plan.
>>>
>>> We go back on shore power and guess what??
>>> Nothing, that's what. And that is with a PD 9145.
>>> The best it would do was 27 amps into a 60% house bank. (So much for
> the
>>> 45 rating.)
>>> Shortly after I got the coach (and fried the first of 2 4Ds), I
> replaced
>>> the buzz box with a PD9145w/wizard.
>>>
>>> It turned out that the culprit here was the #10SAE (~9.4AWG) from the
>> back
>>> to the front that not only supplies all the house electric to the fuse
>>> panel in the back but is expected to do the reverse to recover the
> house
>>> bank from the buzzbox. At only 27 amps, the voltage drop between the
>> PD9145
>>> and the bank was 0.8V. So available charge E was only 13.6.
>>>
>>> This story could go on a lot longer and there are actually many parts
> of
>>> this that have been condensed. I would love to have you think I got
> all
>> of
>>> this figured out this fast.
>>>
>>> Matt
>>> --
>>> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
>>> Electronically Controlled Quiet Engine Cooling Fan
>>> OE Rear Drum Brakes with Applied Control Arms
>>> SE Michigan - Twixt A2 and Detroit
>>>
>>> _______________________________________________
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>>>
>>
>>
>>
>> --
>> Jim Kanomata
>> Applied/GMC, Newark,CA
>> jimk@appliedairfilters.com
>> http://www.appliedgmc.com
>> 1-800-752-7502
>> _______________________________________________
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>>
>
>
>
> --
>
> *John Phillips*
> _______________________________________________
> GMCnet mailing list
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>



--
Plato seems wrong to me today.
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