Help Sizing for small off grid Cabin.

[malfestus]

Hello!
I am very new to solar in general but am looking to start collecting the gear needed to power a fully off grid small cabin.
In no way do I intend to rely on electricity for many of the modern common comforts, but I would love to be able to at very leas reliably run two main things plus some possible other items on a reliable basis.

In order of priority:
1. 1 to 2 5 cu foot chest freezers.
2. A small ductless air conditioner.

Bonus items:
-A light once in a while.
-A laptop/phone charging once in a while
-Possible power tools sometimes.
Id like to start with something that can at very least handle the chest freezers, but running the AC unit during sleeping hours (estimated 8ish hours a day) would be lovely. I DO have a generator but would like to not have to be running it or fueling it all the time.
I have been interested in the MMP all in one's but am unsure with which one would be a good starting point and what to aim for for a battery bank.
Any helpful souls care to provide some basic assistance/suggestions? I would very much appreciate it.

Thanks~

 

[Rednecktek]

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round ) and help figure out which parts and pieces you're going to want to get.

 

[GLC]

Hello!
I am very new to solar in general but am looking to start collecting the gear needed to power a fully off grid small cabin.
In no way do I intend to rely on electricity for many of the modern common comforts, but I would love to be able to at very leas reliably run two main things plus some possible other items on a reliable basis.

In order of priority:
1. 1 to 2 5 cu foot chest freezers.
2. A small ductless air conditioner.

Bonus items:
-A light once in a while.
-A laptop/phone charging once in a while
-Possible power tools sometimes.
Id like to start with something that can at very least handle the chest freezers, but running the AC unit during sleeping hours (estimated 8ish hours a day) would be lovely. I DO have a generator but would like to not have to be running it or fueling it all the time.
I have been interested in the MMP all in one's but am unsure with which one would be a good starting point and what to aim for for a battery bank.
Any helpful souls care to provide some basic assistance/suggestions? I would very much appreciate it.

Thanks~

From experience, my 1 ton ductless unit pulls between 900 and 1300 watts when it is on.
One of my fridges pulls 1.4 kilo watts per 24 hour period. This equals to about 60 watts an hour.
So for how may hours are you going to run an AC?
Lights and phone charging are no issue especially if you are using LED lights. Power tools are another issue.

So an AC running 8 hours per day = 8000 watts. If this is at night time you will need at least 8000 watts of battery storage of LIPO4 to go from 100 percent to 0 in the batteries.
So add a fridge running during no sun collection times add another 1000 watts of storage.
Now we have 9000 watts of storage needed just for those two appliances. using 12 volt batteries in series for 24 volts, you will need 8, 12 volt / 100 AH batteries or 9600 watt hours of battery storage. That is if you started off with fully charged batteries and you take them down to 0 every morning. You will need a minimum of a 3000 watt 24 volt inverter and probably better to be a 4000 watt.
Now if you get appx 5 good hours a day of unobstructed sunlight you will need a minimum of 1800 watts of panels. Lets say you use a 300 watt panel that is rated at 38 open volts circuit with 8 amps per panel. You could go 3P/2S giving you 24 amps and 76 volts. With this and the 1800 watt mark of PV, you may need a MPPT controller of like 80 amps to cover the 1800 watts needed of PV . You could possibly use a 60 amp controller but you will only be able to harvest the 1500 watts at a time but since you are over paneling you could collect more PV in early and evening times. Bear in mind that this is just a minimum. For what you want to accomplish , I would plan for a system at least 20 to 30 percent larger.
These are just quick estimates nothing etched in stone.

 

[Bluedog225]

Welcome. The ac is a big deal. It will dwarf all the rest.

Without the air con, you could have all you need with a small 12 system, automotive/rv stuff, and 12 volt (e.g. ryobi) power tools. And a small LiFePO4 battery.

Maybe a 2 step while you get ready for air con.

 

[12VoltInstalls]

1. 1 to 2 5 cu foot chest freezers.
2. A small ductless air conditioner.

Bonus items:
-A light once in a while.
-A laptop/phone charging once in a while
-Possible power tools sometimes.

By ductless A/C do you mean a mini split?
Need to know the wattages…

Do you have a budget in mind?

Do you want enough battery to go a day or two of rain/clouds?