Help figuring out and sizing off-grid solar system

[chetwynd]

Hi all - I hate to come here and dump this all over you to help me figure out, but I realize that some of you REALLY know your stuff and like sharing your knowledge, and I'd find myself far less confused and frustrated if I could enlist help instead of trying to figure it all out myself.

I have a property in the mountains of Northern California, off-grid, with a well. My goal here is to install some panels and batteries and use it to make my property a bit more comfortable, AND to *potentially* eliminate the need to run my loud and obnoxious generator to power the well pump. It's a property I cannot access in the winter, so I'd bring the batteries up to the property in the spring and bring them home in the late fall. I also only go there off and on throughout the times of year I can access it. Given how much I'd use it, I know this is going to be inefficient.

There are a few things I'd like to be able to run:

1. 4.5 cubic foot fridge/freezer. The one I'm looking at refuses to show a consumption value other than 235 kWh per year. Or, .62 kWh per day.
2. Washing machine. Maybe two loads per week, air dry on a line. Let's say 500 watts for two hours per week. What is that, 1 kWh per week, or .15 kWh per day on average
3. TV: 100 watts, 2 hours per day. 1.4 kWh per week, .2 kWh per day.
4. Lights: let's say 100 watts max, 4 hours per day. .4 kWh per day

So, I'm looking at what, 1.4 kWh per day. At any one time I could potentially be running all of those things at once.

I can get used Sharp NT-175U1 panels for fairly cheap. Can we assume I'll use these?

Electrical Characteristics
Maximum Power: 175 Watts
Voltage at Pmax: 35.4V
Current at Pmax: 4.95A
Short-circuit current: 5.40A
Open-circuit voltage: 44.4V

The panels would be approximately 30' from where I'd have the batteries and charge controller and inverter.

Using the battery sizing tutorial in the stickies:

1400 watt hours X 1.5 (using an inverter) X 2 days of reserve. 4200 watt hours. 4.2 kWh
I don't THINK I'll need more than 1000 watts of panels, so, 12V?
4200 / 12 = 366 amp hours.

Would I want one big battery or multiple smaller ones? If I only need 12v, then I would think a 12v battery or two, wired in parallel?


Without this question being too broad, what should I do?
How many 175w panels do I need? What size/type of charge controller? Inverter?

Thank you for taking the time to read all of this!

Chet

[chetwynd]

Oh, one other variable I'm thinking about is if I ditch the generator that powers the well pump (into a pressure tank), and run that off batteries too. I know that changes things considerably given it's a 240v 1 HP well pump. Is it fairly unrealistic to think I can run that off of a couple of batteries too? It would run something like 30 minutes a day, IF that.

[Mike90250]

> 240v 1 HP well pump. Is it fairly unrealistic to think I can run that off of a couple of batteries too?

That's going to be killer. That will need a BIG inverter to spin up the motor. What about weekly pumping into an above ground storage tank of 2,000 gallons, and using a 12V RV pump to pressurize your house ?

[chetwynd]

> 240v 1 HP well pump. Is it fairly unrealistic to think I can run that off of a couple of batteries too?

That's going to be killer. That will need a BIG inverter to spin up the motor. What about weekly pumping into an above ground storage tank of 2,000 gallons, and using a 12V RV pump to pressurize your house ?

That's one reason I kind of want to keep the well pump separate from this conversation, because I likely will do something like what you mentioned. I don't quite have enough slope to put a tank in the back of the property and gravity feed everything I need, but maybe a pump like you said would work. I don't know enough about it. I also don't know how I'd tie that into the existing system which is really just a well connected to a pressure tank which leads to a series of a couple of hose spigots. I guess a check valve would be needed to prevent it from interfering with the pressure tank and well?