Off grid cabin system upgrade

[ms314]

I recently built an off grid cabin ~500 square ft near the White Mountains in NH. I installed 400W of solar, a 12v 50ah SLA battery and 30A charge controller, and roughly 150W of loads that are wired to 12v (I have LEDs that run on 12v, some phone/laptop/cordless tool chargers, and a composting toilet fan that has to run 24/7). In the next few years I would really like to upgrade the system to accommodate intermittent AC loads up to 3kW - I'm hoping to get an induction cooktop (currently using propane) and level 1 EV charger. Ideally this would be under $5k doing the installation myself.

I realize I should start by upgrading the solar and the batteries and probably switch to at least 24v. I'm planning on adding an additional 2kW of solar and switching the batteries to 2 100ah silicone salt batteries (https://absak.com/product/bolt-12v-100ah-silicone-battery/) wired in series for 24v. Currently I have 4 12v 100W panels wired in parallel. I've never installed this much solar and want to be careful about safety. I'm planning on just wiring two sets of 1.2kW in parallel and putting that in series but that's still 100A... any advice with wiring would be great. Could I put more in series for a 48v input at the charge controller even if my battery is 24v? Or would this depend on the charge controller?

For the inverter, I guess I'm looking for something with built in charge controller and an option for 12/24v DC output for my DC loads, but since I can't find a product like that I'm wondering if anyone has suggestions. I could just get a charge controller/inverter for AC loads, and then get a 24-12 dc-dc step down wired directly to the battery, but I would prefer some type of protection from over discharging. Any suggestions on reliable brands for inverters or other electronics?

Thanks for the help, I appreciate it!

 

[mvonw]

If the property is worth investing in, I'd spend a bit more and get a 48volt system. It's not a lot more money and you have a lot more flexibility. Do you have a well? Generator?
I'm in the Whites and just did my own system for my off grid cabin. Because the property is so unique, it was worth investing in, but I did all myself except the ground mount installation, but mounted the panels, trenching, wiring etc, myself. I used a Sol Ark 12K and could not be happier with it.

 

[ms314]

If the property is worth investing in, I'd spend a bit more and get a 48volt system. It's not a lot more money and you have a lot more flexibility. Do you have a well? Generator?
I'm in the Whites and just did my own system for my off grid cabin. Because the property is so unique, it was worth investing in, but I did all myself except the ground mount installation, but mounted the panels, trenching, wiring etc, myself. I used a Sol Ark 12K and could not be happier with it.

I'm leaning towards 48V too after doing more research on batteries. I'm hesitant to get a really big inverter like because of the cost and my DC loads. But I'm thinking it might be cheap/simple to just get a MPPT controller and separate 3kW non-smart inverter. There are pretty cheap 48-12 step down converters that could power my DC loads. I do have a well but it's pretty far from the cabin so I might get a stand alone solar pump and carry water in.. still figuring that out. I do have a 3 kW backup gas generator.

 

[mvonw]

Are you using the cabin in winter? Is your well dug or drilled?, what kind of pump? Water pumps tend to drive the size of a lot of cabin systems..

 

[12VoltInstalls]

I’d suggest keeping the current system as is. There will be little economy in building on the existing system.
Then build the new system as you wish- with the advantages of having the 12V stuff and the basics covered, the redundancy could be seen as advantageous- or once the new system is proved out sell the existing components to someone who can use them.