50a RV going off-G!

[fobb$57]

Hello all, thanks for having me.
I am needing to put together a system for my 50A camper.
My two main priorities here are budget and longevity of the system.
I will never use more than one 15k btu A/C at a time and the ONLY appliance I will need running constant is a 7cu ft fridge. Cooling is a luxury and I can employ wood heat in the cold months. I have alternatives and not afraid to time my daily usage and forego the conveniences to have power for basic requirements.
I will have a 3550w gen backup.
Basically I would like the CAPABILITY to use more appliances when conditions are ideal, with consideration of budget first.
The panels would prob be mounted stationary on a carport roof.
My estimation lands me at something like (8-10) 300+ watt panels, but I would appreciate any and all inquiries and insight yall can provide here..

Im still learning electrical.. Ive read up on batteries some.
Im wondering for my application would it be better to have say (10) batteries rated 12v 35Ah or (4) at 12v 100Ah?
And wondering about the experts thoughts on arranging banks parallel-in-series.. seems like the way to go but im trying to wrap my head around it all and decipher what would be best for my particular situation..

[chrisski]

If budget is a priority and using solar to generate the power, start with some sort of energy audit. If you go to a sight Like PV watts for your area, you can figure how much power you can produce.

I was floored when I found out what it would take to run one roof top AC, which is what I think 15K BTU is. I didn’t go through with a whole lot of thought on the build, but since the panels would not fit on my roof, and a lot of batteries would be needed, it was looking like I’d need a 10’ enclosed trailer to act as a powerhouse and haul panels around. I also think you’re into forklift battery territory.

If you’re in one place, it may be realistic,

This is my build with Four golf cart batteries set up for 12 volts., three charge controllers, and 1350 watts of panels, I can watch all the TV I want and charge all the cell phones and tablets, not laptops though. That will last me at least five days. If I need to turn heat on, than the propane heater’s electric fan draws 8 amps, and this takes me to about 2 days. When using the microwave, I turn the generator on. I also have a propane fridge. I take my RV out a few days a month, but with the system I got I could live full time with the propane fridge and running the generator for the microwave.

[Mike90250]

Sadly, the mini fridges have lousy insulation, but hey - fridge company is not buying the electricity. And many RV fridges use a 12V heater to emulate the propane (instead of a compressor) so now you are really burning the watt hours vs a compressor. So nail that down first.
Air Con - generator only, unless you want to use a LOT of batteries and a 24V system. Running a air con off 12V batteries is dangerous because the inverter consumes an unsafe amount of amps at 12V.
And 35A batteries are a no-no. plan on using 6v 200ah golf cart batteries - wired 2s 2p

[fobb$57]

Well I would typically have around 5 hours of good sunlight, and this system would be stationary no moving it around.
So if I figure correctly with ideal conditions and (10) 325w panels, I could expect 14.5Kw a day conservatively figured.
Yes the AC burns up some power. I guess 3Kw startup, then about 1500w an hour. Makes me wonder if there is a way to start up on gen power then transition over as its running..??
Why do you require three charge controllers?
Im still trying hard to take all this in, havent even looked into the requirements for controllers and inverters yet..
I also have the option of propane for the fridge. I was just figuring its around 200w an hr. But like I say everything else I can either go without or have zero-cost alternatives for most of the time which is the way id like to stay and avoid fuel use. Next closest absolute necessity would be water heater which I plan to switch on just for a couple hrs every other day when I want a shower.
Good to know about the batteries, thank you.
So bearing in mind that the A/C would be my biggest draw in the summer and I wanted to use it through the hottest 6 hours of a hot sunny day, which also prob coinciding with good supply from 3250w of panels, how many of those golfcart batteries would I be looking at roughly?
You reference wiring them parallel-in-series, right?

[chrisski]

Well I would typically have around 5 hours of good sunlight, and this system would be stationary no moving it around.
So if I figure correctly with ideal conditions and (10) 325w panels, I could expect 14.5Kw a day conservatively figured.
Yes the AC burns up some power. I guess 3Kw startup, then about 1500w an hour. Makes me wonder if there is a way to start up on gen power then transition over as its running..??
Why do you require three charge controllers?
Im still trying hard to take all this in, havent even looked into the requirements for controllers and inverters yet..
I also have the option of propane for the fridge. I was just figuring its around 200w an hr. But like I say everything else I can either go without or have zero-cost alternatives for most of the time which is the way id like to stay and avoid fuel use. Next closest absolute necessity would be water heater which I plan to switch on just for a couple hrs every other day when I want a shower.
Good to know about the batteries, thank you.
So bearing in mind that the A/C would be my biggest draw in the summer and I wanted to use it through the hottest 6 hours of a hot sunny day, which also prob coinciding with good supply from 3250w of panels, how many of those golfcart batteries would I be looking at roughly?
You reference wiring them parallel-in-series, right?

Five hours of good sunlight is what's listed on PV watts? If so that's pretty good. I get between 5 and 8 hours a day in Phoenix, and that 8 hours is with a 14 hour long day.

The 3 SCCs is because I've got three completely different panel sets for my RV.

Just try an energy audit and see how much you need. For overnight storage, I decided on 4 golf cart batteries that cost $1K and store 5.3 KWH of energy and I can use 2.6 kwh of that. As those batteries add up for things like AC and an electric water heater, the cost turned me away from those things.

My batteries are 2S2P. Once you get beyond 3 parallel batteries, you really need to go to a higher amp hour battery.

[fobb$57]

Five hours of good sunlight is what's listed on PV watts? If so that's pretty good. I get between 5 and 8 hours a day in Phoenix, and that 8 hours is with a 14 hour long day.

The 3 SCCs is because I've got three completely different panel sets for my RV.

Just try an energy audit and see how much you need. For overnight storage, I decided on 4 golf cart batteries that cost $1K and store 5.3 KWH of energy and I can use 2.6 kwh of that. As those batteries add up for things like AC and an electric water heater, the cost turned me away from those things.

My batteries are 2S2P. Once you get beyond 3 parallel batteries, you really need to go to a higher amp hour battery.

Yes sir, the annual average is a little over 5 with the worst month being Jan at somewhere around 3.5
Im thinking about having a bank of 8 those gcart batteries 2s2p. Now I understand that would be more storage than what a 3Kw array would produce on even a good day, but im still learning the capabilities of these systems, so my next question can you divert say half of your active solar production to charge batteries while also actively using the remainder? And if so, how?
Would this be a good ratio of array/storage?