My day has finally come! I've been piecing together a system over the last 6 mos and am ready to begin the install. I have 4 105ah agm wired in parallel, 2-210w Evergreen 12v panelsand 2-145w DM solar panels 12v for 710 watts.Controller is a Xantrex 60-150 MPPT.I've been reading solar threads for quite some time and it seems when you think you have the best route planned out, another post makes you re-think things.The plan, as it stands now, is series both sets of like panels for a 24v input to the controller. The trailer (40'toybox) is pre wired with 8 ga wire. Isc on the 210w panels is 12.11a, Isc on the 145w panels is 8.37a so 20.48a @ 24v. I will continue the 10ga wire from both sets to a combiner box and use the pre wired 8ga to the controller approx 15-18 feet. Then 6ga from controller to batts. 60 amp Bussmann hi-amp fuse/circuit breaker before controller and 70 amp of same from controller to batt. They make 60-70-80 amp. Manual said 75 amp at batt's.I am close to max on the 8ga from combiner to controller but there is still a little wiggle room according to wire chart in manual.It states, 20 amps of 8ga @ 12v is good for 11.1 feet. For 24v DC system multiply distance by 2.No plan to upgrade, only wanted to cry once :BWhat say ye ! Thanks

I would love to see how you made it and affixed it to the camper. Also what is your estimate in dollars constructing it. solar power is something I have been thinking about for some time. Any pictures would be nice.

I am confused about your amps. 710w would be approx 45amps Isc with a 12v system.With 20 something amps with 24v system, the MPPT should make up amps from voltage to add to that 20a and get at least 45amps total.Or that could be all wrong.

Wow!!!. Thats a lot of solar (close to 50 amps at full charge capacity) for 420AH of batteries. Except for running Air Cond you should never need a generatorNice System :)

BFL13 wrote:I am confused about your amps. 710w would be approx 45amps Isc with a 12v system.With 20 something amps with 24v system, the MPPT should make up amps from voltage to add to that 20a and get at least 45amps total.Or that could be all wrong.You are correct, should have approx 18 amps before controller and a bunch more after controller.

tanman32225 wrote:I would love to see how you made it and affixed it to the camper. Also what is your estimate in dollars constructing it. solar power is something I have been thinking about for some time. Any pictures would be nice.Going to do a nice write up with pics, my first crack at this so thought it better to ask some of the more experienced here if this is the best way to wire things up. Could also do 48 volt system but didn't think that would be the best way to go with different size panels?

Solar install | Good Sam Community

26 Replies

bigcitypopo
Explorer II
Oct 06, 2013
Sir, do you have install pics around. I'd love to see the layout and install.
big_buford
Explorer
Feb 21, 2013
Finally got to go camping last weekend. REALLY enjoyed the solar! Weather in the high desert was outstanding so I felt I should give the system a good workout :B

Scrolled threw the daily logs today...

Best day was a peak 530w 177ah 2.39kwh

Camped with a really large group so I didn't get to monitor things like I wanted to, next time.

First day I wrote out a few of the output readings:

8am 12.5v 140w 11.5a

9am 13.5v 292w 21.6a

10am 14.4v 342w 23.6a

11:30am 14.4v 243w 16.9a

710w solar thru 60-150 xantrex MPPT controller and 4- 12v AGM = 420ah bank

Think I'm gona like this stuff :B
wintersun
Explorer II
Feb 06, 2013
big buford wrote:
Xantrex manual

Starting on page 2-7 they talk about grounding the system and also ground fault protection :h

If somebody could put that in layman's terms it would be much appreciated. lol, or how I need to hook mine up!

The controllers are designed for residential and commercial use and need to meet the national electrical code standards. Forget about the grounding with an RV as it does not apply.

It is easier to have a way to switch power off from the C-box and also to the battery bank from the charge controller as you hook up the wires. Once the panels are in the sun they are putting out a charge and a shorting of the controller's connections is likely to damage it and the damage is not covered by the warranty. I used Blue Sea switchable circuit breakers to kill two birds with one stone - saves space when wiring everything in place as well.

Be sure that the Xantrex bus will handle the gauge wire that you are running from the C-box and to the batteries. Many controllers will not take 4ga or even 6ga and you may need to add jumper wires. With residential systems the voltages are higher with more panels connected in series and so the wire gauge can be less than with your setup and its relatively low voltage outputs from the panels.
HiTech
Explorer
Feb 05, 2013
I believe it is fine to leave it disconnected or shorted + to - for a few days, but I will let those with more experience comment. The big thing is not to corrode the contacts in the connectors for the panels and add resistance to the circuit.

Jim

edit - smkettner beat me to hitting enter! :)
time2roll
Nomad
Feb 05, 2013
No harm to the panel
big_buford
Explorer
Feb 05, 2013
Does it hurt to leave a panel disconnected and uncovered on the roof for a few days while finishing up the loose ends? I have never read anything about that? Thanks
KD4UPL
Explorer II
Feb 02, 2013
One charge controllers without ground fault fuses the PV - and Batt. - terminals are common. This is not the case with the Xantrex unit. In wiring up the panels to the controller you must connect the + and - PV input wires directly to the controller. You cannot connect the - straight to the battery. The + and - battery terminals in the controller will connect to the battery. Inside the Xantrex controller is a ground fault fuse. It will blow if more than 1 amp of current flows on the ground. This would indicate that your positive or negative PV wire was leaking current to ground somewhere. In order for the fuse to detect this the controller's ground terminal must be connected to chassis ground. It will work fine this way, or, you could not ground the chassis of the controller, thus disabling the ground fault detection feature, and it will work fine that way too.
Ground fault detection is required for NEC compliant residential installations. I don't know if it applies to RV's or not but I assume you're not getting the RV inspected.
The Xantrex XW is a great controller. I've installed around 20 of those with no problems at all.
time2roll
Nomad
Feb 02, 2013
big buford wrote:
Xantrex manual

Starting on page 2-7 they talk about grounding the system and also ground fault protection :h

If somebody could put that in layman's terms it would be much appreciated. lol, or how I need to hook mine up!

Hard to follow. I think you should leave the bonding fuse as an RV system has the battery negative as part of the ground system.

Figure 2-9 says do not connect battery negative to ground :h
BFL13
Explorer II
Feb 02, 2013
big buford wrote:
BFL13 wrote:
Are the 145s Mono? Poly example would be around 17.4 Vmp with two brands I know of

DM Solar

Sticker says 18.7 vmp, could be an error? I notice is says 18.0 vmp on sticker in photo on amazon ?

I thought I had a system where all poly 12v panels had similar specs/watt, but it's not that easy.

Rating- DM145w, Sharp130w, Sun 139w
Voc- 22.3, 21.9, 21.5
Isc- 8.37, 8.2, 8.74
Vmp- 18.7, 17.4, 17.4
Imp- 7.75, 7.5, 7.94

If you used the 145 with PWM you would get Isc for max amps. Compared with the 130 you should get 145/130 x 8.2 = 9.15 but it has 8.37a
the Sun 139 would get higher amps at high noon than the 145.

If you are using MPPT so Imp matters, then 145/130 x 7.5 =8.36 but it has 7.75

It is just math juggling, but it looks like that "145w" is getting killed on the amps side because the voltage component of the watts rating is way high.

There must be a an advantage why they chose to make them that way at the expense of the amps, but I know nothing about that--just trying to have a system that works for comparing panels and those DM145s are throwing my system off :(
big_buford
Explorer
Feb 02, 2013
mena661 wrote:
Are you asking about grounding a Xantrex inverter?

No sir, the charge controller.

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