Hodgepodge system help.

[Reverend Freeze]

II live off-grid in the Arizona desert, and my Generator gas bill is killing me! scored a bunch (150) of Hanwha SolarOne panels, model SF260-36-1P280. I purchased 3 Renology Rover 30A MPPT charge controllers, which I believe can handle 4 panels per charge controller (please correct me if I'm wrong) and a 4000/8000w pure sine inverter. I'm going to be purchasing 8 6V golf cart batteries to wire together into 2 24v batteries, which I understand I need to do before I wire anything, but I'm looking for a resource to show me how to wire everything together, and a list of any extra components I'm going to need to set up my system so it is both safe AND expandable (the ultimate goal is a 10KW system.

Mods or Admins: apologies if this is posted in the wrong place. Please move if necessary.

[SunEagle]

Hello Reverend and welcome to Solar Panel Talk

I see a few issues with your system.

First off while a 30amp MPPT CC can accept 4 of those 150w panels using more than one CC connected to the same battery bank may result in them fighting each other.

Second a 4000/8000w inverter can easily draw more than 200 amp from the batteries which will require big wires and fuses. Connecting large wires to small terminals is an easy way to create hot spots and fires.

Third, while you can build a system expanding one can be a big expense. You would be better off getting an 80 amp MPPT CC which will accept about 2000watt of panels for a 24v battery system. That CC will allow you to expand your system then going with more smaller amp rated CC's.

And finally any parallel wired battery system can create unequal charging and discharging which will kill off one or more of those 6V units.

[chrisski]

Just getting into this recently and building my first system, I toned down my expectations a little bit so that I would run the generator on some high draw stuff, and other than that, I would pull the normal non-large load stuff from my panels and battery pack.

I found with the small generator I had, I went through a gallon of gasoline in for hours, and run continuously for a day, and then day after day, that would be a big deal. So, I when I see myself turning on the toaster, I will power up the generator. For refrigeration, it will be propane powered. Same thing with my water heater. My first go with the propane powered fridge was one gallon of propane lasted three days for night temps of 50 and day temps of 80. I also see myself needing to tuen on the generator for hours at a time to charge batteries on a cloudy day. Not counting the initial costs, I think the cost of this free solar energy will be five times what it would cost to have line power, just because I will need to replace some expensive batteries every few years.

For specifics of my system which is intended to be less than a quarter of what you want, it will be 600 watts of 12 VDC solar panelswired to 36 VDC, going into a 100 volt 60 amp MPPT charge controller, charging 400 amp hours of batteries, which is hooked to a no bigger than 1000 watt inverter. With this, my expectations are that I will be able to brew with an electric pot a single cup of coffee, maybe a couple of times a day, run the lights sparingly in my RV, watch TV, and charge cell phones. If I use a 1700 watt 1.7 liter kettle, I will need to turn the generator on. As far as expandability, I have the option of going to 24 VDC by adding another 600 watts of panels, and I do that with instead of roof mounted panels, I will use ground mounted panels.

The amperage I was using in the DC wire size calculator was a bit more than what @SUnEagle mentioned. I came up with 42 amps at 24 V per 1000 watts. So for a 4000/8000 watt inverter, that's 166 amps normal, 332 amps surge. Those would be some thick wires. As I read the reviews on Amazon about some of the inverters, even the smaller ones like mine are way underpowered battery wise and do not have thick enough wires. Wire runs I was measuring as needing 0 gauge wire for, people would be using 6 gauge wire and giving 1 star reviews for the inverter not working because it either did not pull 1000 watts or even smelling insulation burning when used used, which IMHO is extremely dangerous and the bad review their fault. I've had to change my battery and inverter placement so that the inverter sits as close to the battery as possible, preferably with no longer than 2' cable runs.

I'm taking about four more months until I start drilling into the RV to put panels in it. I want to get this as close to possible correct the first time. If I rushed into it, I would have been in trouble.

For the resource, when you find it let me know. I'm either archaically schooled or self taught. A lot of the guys here either work in the solar industry or are engineers.

[Mike90250]

You need to consider wiring those 8 batteries into a 48V bank, instead of two 24V banks