100 ft. is a lot more acceptible. Huh... I'll have a look at this. We're doing quite a bit of excavation, anyway, for the build...
Reality Check on Building a Family-Sized Home Off-Grid
- Thread starter djparnell
- Start date
HalfBaked
Ever the student
This is also how I do it. I built a passive solar off-grid house in the woods on my 30+ acres, renting my house by the road.
1400sqft, south facing. The south wall is all floor to ceiling windows with a 3' roof overhang. This keeps the sun out in the summer but allows it to penetrate deeply in winter.
I didn't want to live the same as before. I wanted simple, quiet independence and to feel like I'm on vacation in Costa Rica every day. (Live in the hot, humid southeast)
I spent a lot of time with the solar audit in the beginning to see exactly how much power I needed and the equipment required to provide it.
I have a standard size fridge, chest freezer, mini split, tv, starlink, dishwasher, instant pot, microwave, toaster, washer and clothes line. OD propane HW, propane stove. 2 5lb tanks a month.
Use about 8kwh a day. 25kwh lifepo4, 5.5kw pv, 48v 3kva inverter. Running for almost a year now, have not needed the generator yet.
I do pay attention to what the system is doing, but a year has shown me that isn't necessary. We use whatever we want when we want.
Nobodybusiness
Solar Sponge.
Our design philosophy are similar.
Build for peak demand.
Everything in the house is something you can get at big box store.
Or regular HVAC place.
I have considered adding 3 rd inverter to just shove the demand far beyond anything possible now or future.
Plus the added benefit of being able to add more solar.
My current 6 MPPT channels are full.
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I think your correct in most cases for most people , but the price difference depends on where you are and the price for both type fuels…
The price you negotiate for propane can make all the difference…YES , I said negotiate…!
I have been doing it this way for the last decade once I learned the fact about the business of propane ….before that I paid retail like most everyone…
You don’t want to just ask how much is it …and say OK …..God himself didn’t set the price…
Some guy at a desk did… who is he..? He’s just someone who wants all your money …
There can be huge margin in the propane price and it can be negotiated…
No one walks in and say..hmmmmm that car say it’s 55,000 dollars on the window sticker…
Write him a check babe, Let’s buy it…
Nooooo…
I structured a deal for propane always at least a dollar or more less than the normal retail price posted on the wall each day.. …to refill my small 20.lb tanks is the same price I pay for my 500 gallon tank per gallon …about 8 dollars each or less …..the sign on the wall says it’s 18.00…and no one ever questions it…they just pay it….
I have 12 20 lbs tanks and 2 30’s for back up for my big tank…I questioned their price on my first visit and wound up with a decent deal..for the last decade…
Ya have to ask….they surely won’t offer ….he he he.
The going rate around here for truck delivery if you just order it at the normal price is near 2.60 to 4 dollars per gallon plus tax and inspection fee, BS things , and anything else they can think to add to it……
On the last fill up for the 5 little tanks and the big one I’m paying 1.80 per gallon period…don’t know about this fall yet…
You can’t negotiate easily with a power company… unless you are a whopper of a big company …
Don’t be a guppy…beat ‘em up a little bit…they will surly beat you up if ya let ‘em..
J.
chrisski
Solar Boondocker
- Joined
- Aug 14, 2020
- Messages
- 5,470
Build the power line or don’t rent.
I can’t get my family or house guest to obey limits on solar nevermind a renter who’s driven his EV up there and will rig a level 2 charger with an extension cord to an outlet with one leg and an extend cord to another. I see off grid as you having to take many extra trips there.
And then you put up a second off grid cabin and it won’t get better.
If you are not constantly thinking about energy conservation, off grid is not for you.
I don’t think you will have a build and forget situation you desire by yourself, nevermind with renters.
Are there any off grid cabins where you are and if so how long have they been open for?
Snaketzu
New Member
Exactly. YOU buy a 1k gallon propane tank, the propane company is not going to want to lease you one if you don't use much. Then, you watch the price and buy one delivery per year at the cheapest rate you can get. Propane gets a lot cheaper when purchased this way.
Honestly for off the map living you should be supplementing your structure heat with wood. If you have very many acres of forest at all, just the deadfall will support a decent sized structure.
And if the EMP or CME hits, you will be cooking and heating water for a looooong time.
Ha! This is why I posted this here - a reality check. To your point: I don't know of any large-scale off grid operations. I'm not saying that they don't exist; but, if they do, I've not found them yet. And agreed about the the EVs, in particular. I do own a Tesla, and it was a shock to know that the battery was basically the size of a home-based battery bank. Not a good option to charge on a solar operation.
seneysolar
Solar Addict
My 2 cents-
Just size the system for yourself. Get a decent generator thats setup for auto start and the renter income can refill the propane tank if you get some energy hog renters. Set some rules and take a deposit. Just like no smoking and no RV hookups, you can have a no EV charging rule. I suspect 95% will respect the energy usage.
Seems silly to spend $100k for electric in a 1200 square foot house.
Solar panels are still decent price, so over panel like you were thinking but thats all i would do in excess.
Snaketzu
New Member
I'm an electrician not an HVAC guy. I didn't know that heat pumps were getting this efficient and capable. That's very interesting.
When I said heating with electric was inefficient I was speaking of resistive heating elements, I should have been more clear.
This is exactly my concern for anywhere that sees severe winters much less upstate New York. Setting things up to require what are probably the largest loads during the months of the lowest production doesn't match up well. A combo system with a heat pump and propane back up below a certain temperature would do it. I would use a high efficiency wood stove for the back up heat but OP sounds like he's not going to be living there full time for a while yet and wants things to run as automated as possible.
chrisski
Solar Boondocker
- Joined
- Aug 14, 2020
- Messages
- 5,470
I think a Tesla battery is 50 kWh to 75 kWh. A house battery that big is unusual. My Rv has 13 kWh which is huge for an RV and my house had 20 kWh which is average.
Snaketzu
New Member
I installed 96 400W panels on the roof of a purpose designed barn, 4x EG4 18k, 8x PowerPro 14.3kWh batteries. It effectively runs his entire property, 2 barns, 2 wells, 3500sqft house, pool. As far as I know he hasn't paid for electricity since but it was installed last fall, hasn't been through a summer yet.
BUT
He still has his grid tie and his low temp heat, cooking, and hot water are propane.
I don't know how much more large scale things would get for a single property, to be honest. This system would probably handle an EV with ease (he wanted it overdesigned and was willing to pay for it) but I want to see a year's worth of usage patterns before saying for sure. Based on his previous electricity billing and the calculated system output, he could charge an EV a few times a week no problem.
I have had a couple of the 1000 gallon tanks ..I have never been charged rent for one …All 5 companys I dealt with will not fill or work on a tank that’s not there’s.. they will dig it up for you and replace it with their tank usually for cheap ….but I hear that can vary depending where you are…
I do pay 75.00 dollars rent a year for my 500gal…but they all wanted to set the 1000 free if I filled it up…I usually filled it once a year( 800 gallons- 80%).
I didnt get the 1000 this time as it too big to easily hide at this place…
Your right, wood should be factored in as supplemental heat…( your furnace could break ) and even a source of electric back up too ( temporary use) ..
Generally I have found the best time of year up here is in July and august… it can make a big difference when you fill up.. Timing is everything…
This is what I've been looking for. Where is he located - i.e., what is his sun exposure? Also, what is his consumption? My primary residence is a little larger than that, and with 4 people, or consumption was approximately 33kwh per day. (Heating, hot water and stove are gas). Id love to know how often the generator is running. Any chance that he'd speak to me?
I specd it at 96kwh for the house. My model Y is 81kwh.
This sounds like a great set up!
Snaketzu
New Member
Unfortunately, probably not. Very private guy for reasons I'm not allowed to discuss. Signed an NDA for that project, something I've never done before. I don't have remote network access to it either.
He wanted a second barn for horses and he had it built to the south of the house on the north end of a large pasture so it has 100% exposure. Layout was west to east so half of the roof had perfect 180 azimuth orientation with the roof angle set at 28 degrees.
We used combiner boxes with breakers on the strings instead of individual MPPT modules because it is not an occupied structure and doesn't have to have rapid shutdown. It is also a single massive array pointed in the same direction so uneven loading is not an issue.
His annual average daily use was in excess of 70kWh and his production is way more than that. He knew that and wanted enough PV "to cover that roof" and that's what he got (meaning the south facing half of it).
You can get the same production out of fewer panels on a ground mount with bifacials but something on this scale would be radical overkill for two 1200 sq ft cabins or any normal house. He has two wells just on the house grounds one for livestock, two barns, a pool, and an older house that was nice but obviously not very efficient. There was a lot of exterior lighting as well that wasn't LED.
Again, note that he is NOT off grid, he doesn't have a standby generator and his batteries are only being utilized for backup capability.
sunshine_eggo
Happy Breffast!
ksmithaz1
Solar / EV Junkie
I put in an openevse charger., I have two EV's. This would be the one thing that could be a big wrench, however I would provide the charger and connect it up like I do, to a control and make it part of the rental agreement you may only use the provided L2, it may not provide consistent output but will give you any overproduction available. I'd give guidance for daytime charging and bill if you detect an EV type load to cover the generator/propane. I went a little beyond, scripted /controlled so mine only allows charging when the solar batteries are at specific target SOC's, and ramps up the rate as long as I am at the target. Currently my batteries are at 70% with a target of 71 at this time of day, thus the charger would be disabled. I ramp up charging current from 8A in 1A increments as long as the SOC is > 3% over the target. I ramp down in 4A increments if SOC falls below the sliding TGT. I sample every 2 minutes. SOC > 95% (my target ceiling) ramps to 32A immediately. My target floor is 20% at 0730. I will bleed off power from the batteries in the early AM , might as well as long as I can get a full charge (to 90% or so) the next day. I got happy and wrote a script, but the openevse has some integrations where you can do similar things with various platforms to control charging. I would not let this be a deterrent. $100K buys a lot of propane and extra battery. 200KWH in 4 full-size RUIXU racks would set you back around $50K. If at 100% it would charge a Tesla from ZERO and run the house for two days with zero sun. Not sure how many people will be scrambling up there in the grayest gloomiest winter with an EV, but with the artificial government push, the number of EV's will be increasing.
Most people with EV's going up to a cabin, even on grid, don't assume they will have access to more than 120/15a, which is pointless with most electric vehicles these days. The other thing would be to put in an L2 pay station, beef up the batteries, and let the genny take up the slack. Supporting an EV is not that complicated. You'll want a security camera in your parking area/garage.
dougbert
Solar Addict
watch erin and josh who went totally off grid in W Virginia and have been for 5 years.
13kw of arrays, XW+ inverter, backup generator. Josh is an electrician and they built their own system
here is their playlist of solar videos they made
13kw of arrays, XW+ inverter, backup generator. Josh is an electrician and they built their own system
here is their playlist of solar videos they made
Quattrohead
Solar Wizard
That is one heck of a system. Is it possible you could technically describe how you put it all together for example how many batteries connected to each inverter and how that was done for load sharing, how are the inverters paralleled together, how is the PV divided up between the units etc
Hi @djparnell and welcome to the forum. Well, I can't help you too much right now except for my planning, but feel free to follow my progress over the next year or two. My wife and I are building an off grid barn/garage (36x44) with living quarters over it right now (should be weathertight in July) and then a 40x40 home either late this year or more likely next (contractor availability). We're in midcoast-central Maine and given that our current home just a few miles away just sold quickly, we're going to be living there starting in September, in the barn quarters until the house is built (will be pretty nice barn quarters, so not too much of a hardship). So, we'll be decent test subjects, in a real world situation except that we'll likely be less wasteful than renters (we have a house we rent out on VRBO and renters are often horrible about energy use).
I can say that once you solve the heat problem, off grid appears to be attainable. I have several friends in the area who do it now. We're going with a heat pump (not propane) dryer and electric stove with induction cooktop, and heat pump hot water heater, and even then my math says its perfectly achievable as long as we don't try to heat with electric. Both buildings will have R40 walls, R60 ceilings, triple pane (U-factor 0.18) windows but even then, heat (not AC, as summer brings sun) is the real problem. So, we're installing a propane boiler with hydronic heat, and air source heat pumps for AC and even shoulder season (when the sun cooperates) heat. I see no need for air circulation other than an ERV, which accomplishes that and far more, so I respectfully suggest you rethink heating and consider hydronic, as water is a wonderful heat transfer medium - much more efficient than air.
Where things will get interesting for us is when we also install an air-to-water heat pump, once Mitsubishi releases their new model to the US. We'll then automate the hydronic to switch back and forth between that unit and the propane boiler based on outside air temp (not the biggest factor actually) and sun availability (that's the big factor), as the source of heat for the buffer tank. It may take years to break even on that, but since I gave up golf and avoided a boat I need an expensive hobby
.
Where I THINK (we're going to find out soon enough!) many people go astray is a feeling that they need many days of battery backup, no matter what happens. If my math is right, we'll have about 4-4.5 days of battery in the building we're occupying as our primary residence (first the barn quarters, then the house) at just 42KWH of battery, with normal energy use, if we don't use electricity (heat pump) for heat. I'll report back on that through the winter. And if I'm wrong, well, we'll just recharge with a few hours use of the generator, which most people seem to forget or think they need to avoid. If I must recharge even once per week in the worst weeks of the year by running the generator for a few hours, I'm fine with that. It becomes a tool for avoiding a grid connection rather than an emergency backup. Might be worth considering that view. Anyway, once we start the install in a few weeks I'll start a thread in Show and Tell and document what happens.
I can say that once you solve the heat problem, off grid appears to be attainable. I have several friends in the area who do it now. We're going with a heat pump (not propane) dryer and electric stove with induction cooktop, and heat pump hot water heater, and even then my math says its perfectly achievable as long as we don't try to heat with electric. Both buildings will have R40 walls, R60 ceilings, triple pane (U-factor 0.18) windows but even then, heat (not AC, as summer brings sun) is the real problem. So, we're installing a propane boiler with hydronic heat, and air source heat pumps for AC and even shoulder season (when the sun cooperates) heat. I see no need for air circulation other than an ERV, which accomplishes that and far more, so I respectfully suggest you rethink heating and consider hydronic, as water is a wonderful heat transfer medium - much more efficient than air.
Where things will get interesting for us is when we also install an air-to-water heat pump, once Mitsubishi releases their new model to the US. We'll then automate the hydronic to switch back and forth between that unit and the propane boiler based on outside air temp (not the biggest factor actually) and sun availability (that's the big factor), as the source of heat for the buffer tank. It may take years to break even on that, but since I gave up golf and avoided a boat I need an expensive hobby
.Where I THINK (we're going to find out soon enough!) many people go astray is a feeling that they need many days of battery backup, no matter what happens. If my math is right, we'll have about 4-4.5 days of battery in the building we're occupying as our primary residence (first the barn quarters, then the house) at just 42KWH of battery, with normal energy use, if we don't use electricity (heat pump) for heat. I'll report back on that through the winter. And if I'm wrong, well, we'll just recharge with a few hours use of the generator, which most people seem to forget or think they need to avoid. If I must recharge even once per week in the worst weeks of the year by running the generator for a few hours, I'm fine with that. It becomes a tool for avoiding a grid connection rather than an emergency backup. Might be worth considering that view. Anyway, once we start the install in a few weeks I'll start a thread in Show and Tell and document what happens.
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Another consideration for your planning is any local zoning, and building codes, not to forget State health department requirements as well. Single family dwellings versus commercial property can be quite a shock for those first encountering them. For instance you may need a sewage treatment plant. The potable water may be required to be inspected routinely. You may even need to budget for a on sight person if you have several rental buildings to maintain.
My neighbor has a house they put out for rent on one of those online vacation rental sites. It has been a failure in terms of how much effort it has been and where the house is located there is no local or state requirements. They are now attempting to just sell the place.
My neighbor has a house they put out for rent on one of those online vacation rental sites. It has been a failure in terms of how much effort it has been and where the house is located there is no local or state requirements. They are now attempting to just sell the place.
Snaketzu
New Member
I didn't even know these existed. This forum is awesome.
Snaketzu
New Member
Each of 4 18K has 24 panels wired in 2 strings with a DC disconnect.
We didn't want to mess with fused bus bars for the battery bank, so the bank is in fact divided in two and the banks SOC will need to be monitored for divergence. There are two sets each of four batteries paralleled together and wired into two 18K.
I had to completely rebuild his service to make this work within a reasonable budget and it wasn't easy. We started with a 320A service with two 200A panels tapped off of it, with feeders for a pool panel and a barn panel and circuits for two wells all wired into those panels as well as the house loads (this is a common arrangement). In addition, we were adding a new 60A barn panel, and he wanted the system to A) run the entire property and B) automatically switch to battery backup mode without any manual intervention.
My solution is a bit unorthodox.
I used a gutter and tap blocks to split his service into four service drops of 60A fused disconnects (complies with 230.40 Exception 2, 230.46, 230.71(B)) Each 60A service disconnect feeds one 18K inverter. Each 18K inverter output is wired to an adjacent 60A breaker in its own enclosure (complies with 690.12(C)). Each 60A inverter output is then run to a Square D NQ 400A distribution panel at the house. This panel has four 60A breakers for the inverter inputs, two at each end of the bus bar (complies with 705.12). The house panels are fed with two QOB2150VH breakers from this panel. The pool panel, both wells, both barns, the AC condenser, and an SPD are also fed from this panel. The Square D equipment was expensive but the ability to get a single phase 400A panel with bolt in breakers up to 150A without a special order made this a unique solution. I was able to get a used copper bus 400A 30 space NQ interior so that took some of the sting out of it. This panel and its enclosure and breakers still cost around $4k.
Only 18K inverters or those with similar capability can be paralleled in this manner so that they comply with 705.13 and Section 706. Again, I want to state clearly that you can't parallel inverters like this UNLESS they have a Power Control System (PCS) that complies with 705.13 and the 18K inverters do (that's why they are all connected with a control cable).
This effectively downsized his service amperage available from 320A to 240A but based on load calculations this is more than enough. Likewise the two house panels went from being fed with 150A instead of 200A but all of the outdoor loads were refed from the new distribution panel so there weren't any issues.
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dougbert
Solar Addict
so sweet to read of such installations and skillset
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