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Small Cabin Forum / Off-Grid Living / Solar Size Up
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shovelshort
Member
# Posted: 6 Sep 2012 04:17pm
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I posted above that I already have the following: (1) MPPT30 solar charge controller 12V/24V/48V 30A max current(1) Xantrex XPower 1000W inverter 12V battery system compatible only(1) Sharp 230W Polycrystalline panel VOC-36.9V Isc-8.45A Vpmax-29.3 Ipmax-7.85A 600volts max. I also have (2) 6V Interstate Batteries model GCZ-XHD-UTZ 122mins@75amps 232 AH.

I'll be honest I don't really know the difference between an MPPT charge controller and what is offered in the package from Missouri. I have no idea what the advantages are with a MPPT controller. What I do know is that theirs has the battery voltage meter built in that I still needed to buy. The package also has all the fuses, cables, and emergency shut-off that I also still needed to buy. All of this for $450 and I think I might be able to sell what I have for $150 (unused in the box). $300 for a system that is set up correctly and I don't have to keep bugging you guys - priceless.

creeky
Member
# Posted: 12 Sep 2012 11:27am
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thanks shovelshort. I had the same sense of frustration. I thought I would go to a store ... point at a "solar system" and say, "I'll take that one." Instead it took me three months and hundreds of kilometers/miles to put my system together.

okay. to start with, your mppt controller will take your 24* volt panel at 8 amps* (*nominal for the purpose of calculation) and turn it into 12 volts at 16 amps. Your basic pwm controller takes your 24 volts and turns it into 12 volts and keeps the 8 amps. You throw away half your power. Trust me, I've already sold the pwm controller I was told to buy and bought a mppt controller.

So the advantages of mppt are two fold. One, it gets more power out of your panel(s) when it's cloudy, or whatever, and it will change the voltage of your solar input to get the most amps of power to your batteries.

Your system is so small, one panel. batteries at 232 amp hrs at 12v, you really don't need to get to0 wired up. Walmart sells excellent pre-made cables that I used for my first system. You need two 4 gauge cables from the battery to the inverter. Pick a length that's good for your system. I think they go to 3 feet I used 18". You need two 6 gauge cables from the controller to the batteries. I used 3 footers, just the way my cabin was set up. And you need one 4 gauge cable to wire the batteries together, I used a 9"er I think. (Positive to negative to turn your 2 6v batteries into 1 12v battery).

That's what I would do (did). Most small systems run the panels to the controller and the controller to the battery and the inverter to the battery with no fuses or disconnects other than the nuts and bolts or plugs on the battery or controller. Most inverters have internal fuses. I sold my Xantrex Xpower after building the bigger system, but it was excellent! and ran tv and lights and charged batteries ... and was wired with 4 gauge walmart cables direct to the battery. It would have been a hassle if the internal fuses had blown, but after a year they never had ... and a friend gave me 50 bucks to take it to his cabin and he's using it there ... and it stills runs great.

So. you have everything. Take a trip to Walmart and then wire it up!

If you do go Missouri, if the controller really is pwm, replace it with the mppt you already have.

There needs to be a smilie that says, here, have a free beer!

Dillio187
Member
# Posted: 12 Sep 2012 11:32am
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definitely fuse any + wire lead from the batteries, charge controllers, inverters, battery monitors etc. This just protects you from a short should anything go wrong.

CEC2012
Member
# Posted: 23 Oct 2012 10:31pm
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battery Specifications

20 amp hour rate:230
5 amp hour rate:174
6 amp hour rate:178
BCI Group Size:GC2
Minutes at 25 amps:448
Minutes at 75 amps:120
Volts:6

project
6v gc2 Duracell at sams club ( 4 ran in series) =24vdc

I am running (8) 2 amp-24vdc led flood lights =20 amps x 8 hrs/day =160 amp hours per day
4x 240 watt sharp modules
45 amp tri-star mppt charge controller
Do I have the hours i need????

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