Off-Grid Solar for Full-Time Residency

[Old Man Oldman]

Hello everyone. I'm putting up a pair of yurts that I will [eventually] use for my permanent residence. I am close enough to town that I can connect to the grid, but the power company won't hook me up unless I have a septic system, and I plan on using a gray-water system and a composting toilet instead. For that reason, I would like to do off-grid power. I'd love to hear from anyone who has done this on their own, either using a 'turnkey' kit or assembling one from parts. Cheers, Doug

[hierony]

I'm planning on going solar slowly--I need to wire up my 24 V lights, get the 12 V water pump setup better, get a low power (300W?) & high power (1.8-2 KW) inverter, then finally large batteries & solar panels, maybe a generator. I do things the hard way though, so I might just buy solar cells and make my own panels.

I use about 2 KWHr a day (electric lights, kitchen, laptops/chargers). No hot water though

Right now I run off a 50 ft 10 ga extension cord from the power pole. It seems weird electric won't put in a utility pole--that's often the first thing to go up when anything gets built (power for contractors to run tools). I understand they won't attach it to a yurt, but I know pump houses that have their own box...

[Old Man Oldman]

I spoke to a guy from our electric co-op and found out why they won't put up a pole for a residence unless you have water & septic but they will do it for a business: businesses must pay 100% of the cost of putting in that pole. The electric company is happy to foot the bill for extending a power line to a residence with water & sewer because they know that even if you move out after a few months, someone is likely to take your place, making the utility pole a sound long-term investment. I plan to get a propane tank (provided they don't have the same water&septic prerequisite for service!) so that will provide hot water. I will probably also get a propane refrigerator to keep the electricity consumption down. Those things are awfully expensive though -- 2x-3x the price of a comparable electric fridge.

[Jafo]

I have an off-grid solar setup at my camp (yurt). I have a bit of experience with this. Much of the answer is going to depend on how much power you expect to be using a day?

[Old Man Oldman]

I filled out an "off-grid daily load worksheet" that I found on an solar power website, and came up with about 4300 daily AC power watts. The two biggest contributors to that total are the water well pump (I assumed it's 3/4 hp but I have no idea) and a clothes washer.

[hierony]

Ah, the electric co-ops that serve rural areas operate differently than the larger corporations--here they charge $20 base monthly fee vs $6 for the larger power companies.

I've two ac chest freezers, one of which I converted to a fridge. Together they average around 35 watts continuous (840 W*hrs daily). Fridge is 5 cu ft, freezer is 3.5 cu ft. Works decently, though takes up a little more floor space.

Solar is expensive. A crude estimate is somewhere around $1000/KW of panel and $120/KW*hr battery (at a quickly wearing 100% discharge), plus all your wiring, controllers, & inverters, and installation. It pays to reduce your usage as much as possible...

I haven't seen many numbers for what it takes to run a well off solar--probably highly variable (depth, pump, water usage). Pumping irrigation water gets expensive even on grid-tie systems. If you don't have power, I'm guessing you don't have a well yet either. I'd be tempted to setup a large cistern in an (insulated or not?) shed and pump it full running off a generator--fill it up once every few days or every week? Once a month if you're really good with your water usage. Then you don't have to worry running out of power and not having water, getting a 240 V inverter, etc.

There's also solar water

heating

...

[Jafo]

If you are in a place where you do not have to worry about freezing, you may want to consider pumping to a holding tank, that way you can pump when you have surplus power.

From your workload sheet + room for growth and unexpected usage, let's say you probably use 6kw a day. You can't size the bank to hold just 6kw. You should really only plan on using 20% of your battery bank up at any given time, otherwise you will quickly kill your batteries. So we need a bank capable of holding 30kw.

Now we need to consider your battery configuration:

Ampere hour to Kilo watt hour Conversion | EverydayCalculation.com

Most of your batteries come in 12volt and you can wire them in series to get them to the voltage you desire. Note, the higher the voltage, the more costly things become. For arguments sake, let's say you were going to go with 24 volts like Hierony and myself have. That would mean you would need 10 of these batteries (the best non-lithium based batteries IMO):

https://www.amazon.com/dp/B004FWAXU6...rldwidecreatio

wired in series + parallel (Btw, you can get them cheaper here). Using the cheaper source, that comes to about $6,497.10. Wiring, fuses, etc., probably more like $6,750.

You will now need a 24v inverter (pure sign) to handle preferably double the wattage you expect to use at any one time. Here is a 1,500 watt, 24v inverter that I have for my setup:

https://www.amazon.com/dp/B00153BE6A...rldwidecreatio

I am imagining you might need more than 1,500 watts though, so price accordingly.

Then you will need panels enough to be able to charge and maintain your bank. This gets a bit trickier because it depends on voltage, location, sun and type. A very rough rule of thumb though is that the panels themselves should cost about half the battery bank, so expect another $3,000 in panels and probably another $1,000 for the rest of the equipment including a good charge controller which is absolutely necessary.

So we are probably looking at a minimum of a $12,000-$15,000 initial investment, which a lot of room for variables. Let's not forget that the best battery banks still must be replaced often, so you will have to shell out another $7k in about 5-10 years.

You may also require a propane backup generator for days with extended cloud cover.

Enphase ( https://enphase.com/en-us ) may have some good solutions too, but I would be surprised if they come in cheaper than that as they use Lithium batteries.

Now there are ways to shave off costs.. Use propane for cooking and water

heating

. Wire everything to use LED lighting. Consider pumping to storage tanks using a wind turbine or some other solution. Etc..

I hope that helps!

[Old Man Oldman]

Originally Posted by hierony

Ah, the electric co-ops that serve rural areas operate differently than the larger corporations--here they charge $20 base monthly fee vs $6 for the larger power companies.

I've two ac chest freezers, one of which I converted to a fridge. Together they average around 35 watts continuous (840 W*hrs daily). Fridge is 5 cu ft, freezer is 3.5 cu ft. Works decently, though takes up a little more floor space.

Solar is expensive. A crude estimate is somewhere around $1000/KW of panel and $120/KW*hr battery (at a quickly wearing 100% discharge), plus all your wiring, controllers, & inverters, and installation. It pays to reduce your usage as much as possible...

I haven't seen many numbers for what it takes to run a well off solar--probably highly variable (depth, pump, water usage). Pumping irrigation water gets expensive even on grid-tie systems. If you don't have power, I'm guessing you don't have a well yet either. I'd be tempted to setup a large cistern in an (insulated or not?) shed and pump it full running off a generator--fill it up once every few days or every week? Once a month if you're really good with your water usage. Then you don't have to worry running out of power and not having water, getting a 240 V inverter, etc.

There's also solar water heating...

I actually do have a well. Its pump is powered by a 240v gasoline generator. I have thought about the cistern approach -- I'm guessing it would need to be insulated, as I'm in central Ohio.

Thanks for your suggestions. Lots of food for thought here.

[Old Man Oldman]

Originally Posted by Jafo

If you are in a place where you do not have to worry about freezing, you may want to consider pumping to a holding tank, that way you can pump when you have surplus power.

From your workload sheet + room for growth and unexpected usage, let's say you probably use 6kw a day. You can't size the bank to hold just 6kw. You should really only plan on using 20% of your battery bank up at any given time, otherwise you will quickly kill your batteries. So we need a bank capable of holding 30kw.

Now we need to consider your battery configuration:

Ampere hour to Kilo watt hour Conversion | EverydayCalculation.com

Most of your batteries come in 12volt and you can wire them in series to get them to the voltage you desire. Note, the higher the voltage, the more costly things become. For arguments sake, let's say you were going to go with 24 volts like Hierony and myself have. That would mean you would need 10 of these batteries (the best non-lithium based batteries IMO):

https://www.amazon.com/dp/B004FWAXU6...rldwidecreatio

wired in series + parallel (Btw, you can get them cheaper here). Using the cheaper source, that comes to about $6,497.10. Wiring, fuses, etc., probably more like $6,750.

You will now need a 24v inverter (pure sign) to handle preferably double the wattage you expect to use at any one time. Here is a 1,500 watt, 24v inverter that I have for my setup:

https://www.amazon.com/dp/B00153BE6A...rldwidecreatio

I am imagining you might need more than 1,500 watts though, so price accordingly.

Then you will need panels enough to be able to charge and maintain your bank. This gets a bit trickier because it depends on voltage, location, sun and type. A very rough rule of thumb though is that the panels themselves should cost about half the battery bank, so expect another $3,000 in panels and probably another $1,000 for the rest of the equipment including a good charge controller which is absolutely necessary.

So we are probably looking at a minimum of a $12,000-$15,000 initial investment, which a lot of room for variables. Let's not forget that the best battery banks still must be replaced often, so you will have to shell out another $7k in about 5-10 years.

You may also require a propane backup generator for days with extended cloud cover.

Enphase ( https://enphase.com/en-us ) may have some good solutions too, but I would be surprised if they come in cheaper than that as they use Lithium batteries.

Now there are ways to shave off costs.. Use propane for cooking and water heating. Wire everything to use LED lighting. Consider pumping to storage tanks using a wind turbine or some other solution. Etc..

I hope that helps!

I had already shaved a lot when I filled out that spreadsheet-- propane water heating and cooking, propane fridge, no TV, etc. I specified one 60W bulb for lighting, thinking that 6-8 LED lights would approximately equal one 60W bulb. After I nuked the washing machine, coffeemaker and toaster from my setup and changed the well pump from 3/4HP to 1/3HP, I got the daily watt consumption down to about 2200.

$15K up front and $7K in 5-10 years? That's rough, but on the other hand I'm looking at $10K or more for a septic system I don't really need, and paying the electric company every month. Decisions, decisions.

Thanks for the information. This is a lot to digest but it's very helpful.

[Jafo]

Originally Posted by Old Man Oldman

I had already shaved a lot when I filled out that spreadsheet-- propane water heating and cooking, propane fridge, no TV, etc. I specified one 60W bulb for lighting, thinking that 6-8 LED lights would approximately equal one 60W bulb. After I nuked the washing machine, coffeemaker and toaster from my setup and changed the well pump from 3/4HP to 1/3HP, I got the daily watt consumption down to about 2200.

$15K up front and $7K in 5-10 years? That's rough, but on the other hand I'm looking at $10K or more for a septic system I don't really need, and paying the electric company every month. Decisions, decisions.

Thanks for the information. This is a lot to digest but it's very helpful.

If you can shave it to 2,200 then you could get away with a smaller system. If it were me? I would look for cheaper ways to do the septic. Is the soil sandy? You could dig it by hand really and just put in the smallest tank allowable (as you won't be using it). That's what I would do, try shaving costs off the septic.

I like my off-grid system, but I wish it were possible to get grid power. I would do that in a heartbeat. There just is no power for miles from my camp. My small system (two of those batteries) came to about $3-4k as I recall when all was said and done.