halfmoonhomestead
New User
- Location
- Maine
- Occupation
- Engineer
I'm about to purchase a cabin in the middle of the woods. The house site is completely off grid, with a small solar panel array, some lead-acid batteries, and an ancient pair of 20-amp inverters, providing your typical residential 240/120V single phase power.
Now, we plan on making this cabin our permanent residence, and we know that the 2.2kW solar array just won't be enough for us in the darker months.
There are really two options to increase our power supply: First, we can get a bigger array and more batteries. I'm sure the dated inverter and charge controller will need to be replaced as well, and we would probably want a Generac or something similar to provide power for those long periods when the sun just refuses come out. After all things said and done, even if we were to do most of the labor ourselves, we're probably looking at a $10,000-$20,000 price tag, if we're lucky.
Then there's the second option: we connect to the grid! The road is about 800 feet from the house. Paying the utility company to run service to our house would most definitely be more expensive than vamping up our solar setup. Plus, we don't want to see ugly power lines run through our beautiful land.
But then I did some calculations, and realized that laying some underground cable might be feasible. 120V, 5% drop, 800 feet, aluminum wire at 30 amps requires 4/0. And you can get 500 feet of direct burial 4/0-4/0-4/0 from Home Depot for $3000.
So here's the plan:
Has anyone ever done or heard of something similar to this? Am I insane or does this actually make sense? What am I missing?
Now, we plan on making this cabin our permanent residence, and we know that the 2.2kW solar array just won't be enough for us in the darker months.
There are really two options to increase our power supply: First, we can get a bigger array and more batteries. I'm sure the dated inverter and charge controller will need to be replaced as well, and we would probably want a Generac or something similar to provide power for those long periods when the sun just refuses come out. After all things said and done, even if we were to do most of the labor ourselves, we're probably looking at a $10,000-$20,000 price tag, if we're lucky.
Then there's the second option: we connect to the grid! The road is about 800 feet from the house. Paying the utility company to run service to our house would most definitely be more expensive than vamping up our solar setup. Plus, we don't want to see ugly power lines run through our beautiful land.
But then I did some calculations, and realized that laying some underground cable might be feasible. 120V, 5% drop, 800 feet, aluminum wire at 30 amps requires 4/0. And you can get 500 feet of direct burial 4/0-4/0-4/0 from Home Depot for $3000.
So here's the plan:
- Build a little shed at the entrance to our driveway
- Ask the utility company to install service for our "shed". They'll need to pop in a transformer and a meter. Not 100% sure what that would cost, but I'd guess $1-2K?
- Dig an 800 foot trench with my backhoe from the shed to our house
- Throw in 800 feet of 4/0-4/0-4/0. $6000 with 200 feet leftover to use elsewhere
- Connect the wire to a transfer switch at the main panel in the house with a 30-amp breaker. Down the road, it would be nice to upgrade to a grid-tied inverter so we can sell power back, but for now it would just be treated as a backup, completely separate from our current setup. Batteries drained? Flip to the grid.
- Where I live, permits and inspections are rarely needed for anything. You can build a whole house by yourself and no one bats an eye.
- I know 30 amps is not much, but it's 50% more than our current inverter output! Besides, our range, dryer, and hot water heater are all propane, and we heat with wood. The biggest load would be when we have a toaster, coffee pot, and microwave on at the same time.
Has anyone ever done or heard of something similar to this? Am I insane or does this actually make sense? What am I missing?
