We’re often asked for details and specs on our solar/wind setup, especially when we talk about the abundance of power we have 9 months of the year. That abundance of power (and honestly, lack of battery storage) means that we’ve come up with some pretty extravagant ways to use the free glut of summer power.
I’m not complaining, I love being able to live in modern luxury while off-grid 9 months of the year. The other three power-starved months are another story…
Nonetheless, you asked for it, you got it. Here’s the story of our system.
When we found our off-grid homestead, we were intimidated. We’re agriculturalists, not tinkerers.
Both of us lack the mechanical aptitude to repair a car, regardless of how much time we put into trying to learn. A whole-house solar system was daunting, to say the least…
Beyond that, we were moving in blind, with no spec sheets or system documentation. The builder/owner had died, leaving no notes about the design. Much of the system was unfinished, literally open wires alligator clipped together dangling in the basement.
The house had been vacant for 2 years, and some of the system was in disrepair.
It took us over a year to get it functioning on a consistent basis, and even longer to feel like we even understood the basics of the system. After 5 years on our homestead, we’re still learning every day, and making improvements anywhere we can.
AC and DC Wiring
The entire house is wired in both AC as well as DC wiring. The wall outlet plugs are set up with two different outlets, and all critical systems run on DC (direct current) electricity straight from the batteries.
That includes the refrigerator, chest freezers, lights and heat pumps for radiant floor heat. That means that the inverter can be turned off at night to conserve electricity.
The AC side of the house powers things like our computers, the well pump and other modern electronics that you’d use during daylight hours.
Our setup has a total of 12 solar panels. Four of the panels are on our attached greenhouse, and they provide shade for the plants during the hot summer months.
During the winter months, the solar angle changes and they don’t shade the plants. When the snow flies, the heat in the greenhouse means that the panels melt out quickly.
These 4 panels were enough to supply the house with electricity, and did so without a backup generator for 10 full years from 1997 to 2007.
Later, a shop/office was added and 8 panels are high up on its roof. These panels are more modern, installed in 2007, but they’re still 10 years old and not as efficient as today’s panels.
The roof on the shop is super-insulated, and holds snow for long periods, meaning that these are encased in ice during cold spells.
When the shop roof is iced in during the winter months, we tend to get some power from our wind turbine to help make up for the loss of solar.
To get the specs on the greenhouse panels, we took a picture of the specs sticker on the back and zoomed in. Those things are way up there, but since they’re on the greenhouse at least we can see the back of them. But this spec sheet shows that they’re 300-watt panels.
The panels on the shop are still a mystery. We’re going to assume they have the same output, but we’re not exactly taking them down to check.
If they’re all the same, our total solar generation capacity is 3.6kW.
Take a look at that close-up picture, there’s a lot of information there.
Here’s a translation:
Pp: Maximum nominal power (ie these are 300W panels)
Voc – Open Circuit Voltage. Theoretical maximum voltage with zero resistance
Isc – Amperage with Short Circuit. Again theoretical maximum with zero
resistance, as if you took the two wires from the panel and short-circuited them together
Vp – Voltage at max power ie ideal conditions
Ip – Current (Amperage) at max power
Notice 17.5 volts * 17.1 Amps ~ 300 Watts
For more information on translating solar specs, check out this article.
These are some old panels, circa 1997. Energy efficiency has improved over time. If you’d like to know how much, check out this graph from the National Renewable Energy Laboratory.
Our wind power comes from a Bergey XL1 (1kW) wind turbine on an 80-foot guyed tower. The problem is, we hardly ever see wind.
We’re located in a micro pocket where there’s hardly any wind, even above the tree line. The air is still, and the wind turbine only turns during storms or in foul winter weather.
Why was it installed? Good question.
Our house was built by a solar contractor, and he needed to train and practice installing wind systems. What better way to learn than to install one on your own land?
Even if the wind did blow, a 1kW model is relatively small for wind power. I did a bit of research as to costs and found that about half the cost is in the tower. For ballpark figures, the turbine itself is about $4500 new, and the tower is roughly $3000 plus installation costs.
The manufacturer recommends a 6kW setup to power small homes and energy-efficient farms, but one of those will set you back about $22,000 plus tower and installation.
In our case, the wind turbine actually is really helpful just for the tower, even though we don’t get much wind. We get our internet through a radio internet provider, and the receiver in the picture above only works because the wind turbine gets it above the tree line.
Hooray for high-speed internet, but an 80-foot tower is a pretty expensive way to get it when you’re not getting much wind…
The generator was added after the initial owner died, as a requirement imposed by the insurance company before the sale. The house ran without it, under careful stewardship, for 20 years.
Under our inexperienced stewardship, the generator saw heavy use our first winter, and still a good bit of use every winter since.
It’s a Kohler Model 8.5RES rated for 7.5kW.
It’s wired so that there’s a bypass and the house can run directly from the generator even if the inverter, batteries or the rest of the system isn’t functioning. We can also run it back through the inverter to charge the batteries. Both have come in handy, believe it or not.
When we blew a fuse over a holiday weekend, the batteries weren’t charging from the panels, and the generator couldn’t get power to them. We were still able to run the AC portion of the house directly from the generator.
We have a 24-volt system, with three 8-volt lead-acid batteries (Model: Rolls 8CS25P). Since output depends on how quickly you draw them down, here are the actual specs per battery:
394Ah @2hr, 640Ah @8hr, 853Ah @24hr, 1,156Ah @100hr
If you’re slowly using your batteries at a baseline level, they’ll keep the house powered a lot longer. In the wintertime, unless we’re actively charging, we don’t use anything but the base load of the freezers if we can help it.
I often see others quote their battery capacity in kW. Since battery output varies based on how quickly you draw them down, it’s hard to give a good number in kW.
A reader sent me a note telling me that there is, in fact, a convention for how battery kW hour ratings are developed:
“The Rolls Surrette batteries you have are 820 amp-hours @ the 20 hr standard rate. Since you have three 8 volt batteries in series, the amp-hour capacity of your bank is also 820 amp-hours.
With your 3×8=24 volt system, you would therefore have a total theoretical battery bank capacity of 820×24=19,680 Watts-hrs (or 19.6kWh).
Since you NEVER, ever want to discharge your bank more than a 50% depth of discharge, your total usable bank capacity would be 1/2 of 19680 Watts-hrs = 9.8kWh. That 9.8 kWh value is the only one you want to consider quoting, and that is the real total MAXIMUM energy budget you can use before you absolutely must fully recharge your bank.
In reality, I think that a 20% maximum depth of discharge (I.e., staying at 80% capacity) is the best way to extend your battery bank life. Using just 20% for your bank would mean an energy budget of 3900-4000 Watt-hrs per charge cycle. My guess, based on your house description, is that would be close to your daily power usage, so that would only give you 1-2 days autonomy between complete recharges.”
That seems pretty accurate to me, as we do tend to have 1-2 days of complete autonomy on our batteries if there’s absolutely no sun (or the batteries are encased in ice in the winter).
I would absolutely love a longer period of energy independence between solar re-charges, as often we have no sun for longer than that. Ideally, I’d hope for at least 3-5 days, and then we’d almost never need a generator.
The previous owner was running 16 batteries of a type no one seemed to be familiar with. They were completely dead and wouldn’t hold a charge, and we replaced them when we moved in.
We were told that these three Rolls batteries would be more than enough. In hindsight, I would have gone with double the capacity. We fill them before noon in the summer and are power scarce with a lot of generator usage from December through February.
Inverter & Charge Controllers
Our inverter is a Magnum Energy MSH-RE series inverter model number MSH4024RE. It’s rated for 4000 watts of continuous power output, or up to 5800 for a 5-second surge.
Since our system is a bit cobbled together, we’re running one Outback C40 charge controller and two Outback MX60 controllers.
Full System Specs
Solar: 12 Solar Panels, 300 watts each, for 3.6kW
Wind: Bergey XL1, 1kW wind turbine
Battery Model: Rolls 8CS25P
Battery Specs: 394Ah @2hr, 640Ah @8hr, 853Ah @24hr, 1,156Ah @100hr
Battery Output @100hrs: ~27k watt-hours
Inverter: Magnum Energy MSH4024RE, rated at 4000 watts continuous output
Charge Controllers: Outback MX60 and Xantrex C40
Any questions? Leave them in the comments below.
I didn’t see what state this is, and the nearest, well big town.
What is the name of contractors, and contact info.
This is in Vermont, in Washington County. The home was designed and built 20 years ago, and the contractors are no longer in business.
Hey Happy New Year! I just stumbled across this site while researching attached greenhouses. As it turns out, my wife and I just bought an off-grid home in Johnson, VT and much of the system seems to be very similar to yours. Our place hasn’t been lived in in 3 years because the previous owners died, we have the same Kohler generator (does your run off propane?) and I believe we have the same batteries and inverter. We had the batteries installed this past summer by a great guy named Nathan Skorstad, but haven’t purchased or installed any panels yet, we have many trees to cut down first. We call our place Baumhaus. My wife is from Germany and baumhaus is treehouse in German, which is how we think of our home.
Anyways, we’ve been looking around our new house and thinking about how to make it more efficient and slightly larger and more off-grid, I guess you could say. We just had a baby and are both self employed so we’ve had a lot of time this winter so far to look around and day dream. Sufficive to say we will be reading through your blog for the foreseeable future. Your house looks beautiful by the way. I’m hoping to come across some interior pics around here somewhere.
Wonderful and happy to have you! We looked at a number of places in Johnson, so I wonder if you ended up in one of them, lots of nice places out there. Yes, the generator runs on propane, and if you find someone to service it that you like, send them our way! We always have trouble finding help when it has issues.
I’m hoping to put up more interior pictures, and a tour that’s more than just the solar specs at some point. We have 2 young children, both under 3, so currently, every surface is covered in boogers, thrown spaghetti, blocks and plush toys. Someway, when I dig out I’ll be able to take a few respectable pictures. Hopefully soon, wish me luck!
Great info! Just wondering which brand/model DC refrigerator (and freezers) you got that works for you. We have heard mixed reviews on some brands and would love to know! Thanks!!!
Hey Jaime, happy to help!
Our refrigerator is a Sunfrost RF16 (http://www.sunfrost.com/RF16_efficient_ac_dc_refrigerator.html) and it works wonderfully. The tech support has always been great anytime we’ve had an issue. I called looking for recommendations for repair people, and they laughed and said there’s no need for a repair person, they’re simple machines and he could troubleshoot it over the phone. I described the issue and he told me how to fix it in about 5 minutes.
Our chest freezers are from SunDanzer (https://sundanzer.com/product/dcr225-dcf225/) and we’ve never had any issues what so ever with them.
Awesome! Thank you so much!!! 👍🏻😊
Eric, do you know how to get in touch with Nathan Skorstadt? I used to work with him at Independent Power LLC in Hyde Park. I work for Peck Solar now and we only do grid-tied solar. I’m trying to direct off-grid business back to Nathan, but I’ve lost his contact information.
We are moving to Colorado (330 average days of son) to build our dream home out of shipping containers and incorporating Earth Ship technology elements. Looking forward to this going to take 3 years. We will purchase the approximately 40 acres debt free and cash flow the rest. Husband ‘bring home the bacon’ and I manage the property improvements. (I have a construction & safety management degree.)
Sounds like the perfect setup! Good luck with your adventure =)
Hello, what is the rough average price for an off grid homestead in Vermont? Say 10 acres like yours. Also what size system would you need to not have to run a generator? ( all renewable). Finally how much wood do you burn in a year? I just came across your website and love it! I’ve always wanted to do the same thing but was afraid I was not technical enough. The fact that you weren’t either is so inspiring that I think maybe I can do it. Thank you so much!
It depends. The average price of a home in Vermont is around 250k, and you can find off-grid homes with land for under 100k in remote areas or over a million if they’re a serious mansion. Off-grid is generally cheaper, because they have a smaller set of people that want to buy it, but it’s really going to depend on the specifics of what you’re buying. There are affordable options to be sure though.
Our setup would be big enough to never run the generator and live in total comfort if we were in an area with good wind, had a gravity well for water and a battery bank twice as big as what we have. Pumping water uses a lot of electricity, our batteries are too small for our system and our windmill is almost useless in our location.
For wood, we heat 2 buildings with an external boiler through radiant heat. Both are super insulated. Our house at 1200 square feet, and a shop/office that’s a garage on the first floor and office above (about 2000 square feet). Originally we were burning hemlock which has a low BTU because we had a lot of it, and you can burn it if you have an external boiler. That took about 6 cords a year. This winter we used dry hardwood, which is what most people use anyway, and even though it was a cold winter we only used 3 cords.
You can really get a livable house with land for $100,000? I realize it will be small and remote but that is encouraging. What would you say is the necessary income to have for a family of 4? This is fascinating. Thanks.
Thank you! Was that 100000 for land and a house? Also did you mean3 cords of wood for both the 1300 sq ft house and the 2000 sq ft office? Thanks
Simple analysis on Solar power from you. May I know how many years has those Rolls battery have been in use.
They’ve been in use 6 years as of this fall (2018).
Fellow Vermont Off-gridder-and-Enginerd
Some help with your battery sizing questions….
Off grid flooded lead acid batteries are usually (by reputable battery manufacturers) quoted by their 20 hour rate. That 20 hr rate is important to know, because, as the industry standard value, it is the “capacity” by which all of your charge parameters should be set on your charge controllers to maintain proper battery life.
The Rolls Surrette batteries you have are 820 amp-hours @ the 20 hr standard rate. Since you have three 8 volt batteries in series, the amp hour capacity of your bank is also 820 amp-hours. With your 3×8=24 volt system, you would therefore have a total theoretical battery bank capacity of 820×24=19,680 Watts-hrs (or 19.6kWh). Since you NEVER, ever want to discharge your bank more than a 50% depth of discharge, your total usable bank capacity would be 1/2 of 19680 Watts-hrs = 9.8kWh That 9.8 kWh value is the only one you want to consider quoting, and that is your real total MAXIMUM energy budget you can use before you absolutely must fully recharge your bank. In reality, I think that a 20% maximum depth of discharge (I.e., staying at 80% capacity) is the best way to extend your battery bank life. 20% for your bank would mean an energy budget of 3900-4000 Watt-hrs per charge cycle. My guess, based on your house description, is that would be close to your daily power usage, so that would only give you 1-2 days autonomy between complete recharges.
Our off-grid house is on its third system configuration, so no worries if ther are more “lessons” to come!
Oh the lessons definitely keep coming. I feel like we stumble into new knowledge about our system and the various components at least every few weeks. Keeps it interesting to say the least. Thank you for the info above, and it’s always nice to connect with a fellow Vermonter and off-grid nerd. *waves hello across our small cozy state*
Thanks for sharing! We live in southern Ohio in a big valley. We are completely off-grid and learning as we go also. We have a 48 volt battery via solar or generator that also has the bi-pass to run the house directly on generator. And yes, we’ve had use for that also LOL! We are looking into adding wind as another back -up as we find we need it for winter when the sun is lower on the Earth and doesn’t shine much. We luckily have a wood stove for heat. For 5 winters, we’ve used our Hardy heater and at times the inside wood stove. The Hardy heater was such a drain on our batteries, we gave it a try this winter without it and are using so much less wood, probably using 1/4 of what we used to! I’m also interested in learning more about your radio internet service. Currently we have satellite since we aren’t connected to anything and are limited for usage and is constantly very slow. Seems like you can never have enough back-ups to your back-ups. We have a couple creeks that run by the house also but we’ve found out they are just ‘too’ far away for the amount of electric it would bring.
Hi Ashley, what a beautiful home! I’ve been researching solar panels as my parents are thinking about making the switch and just came across your article. Thanks for sharing your insight, it sounds like a really great system you have going on.
Wonderful, glad it was helpful!
Helping grandson set up off grid in north part of Arizona. Have lots of sun and wind. We can purchase used great shape solar panels for $50 each. They come from solar farms that upgrade to latest and greatest. Most are about 6 or 7 years old and 250 watt. Any ideas on amount needed for family of seven (5 kids under Elevation is at 6000 feet or so.1 Have 40 acres 20 miles from town – St Johns and no power or natural gas. Haul water from common well 1 mile away. And good books you recomend?4)
I wish I could help you, but I’m definitely not expert enough to help with sizing a system.
Is the water borehole / well or spring. If it’s spring consider a hydraulic ram pump. We are spring fed. The spring is 220 m horizontal and 60 m vertically below the property and it is pumped up via a hydraulic ram pump which will be celebrating it’s hundredth birthday in 6 years time. We replaced the drive pipe in 2015 and refurbished the pump using the same company which made it! Blakes Hydram… Now part of another ram pump company (sold 2022).