Using Energy Wisely Off-Grid


Inside this Article

Seasoned off-gridder Roy Rakobitsch with his wind- and PV-powered minisplit heating system.
A minisplit heat pump (indoor unit pictured) can move three units of heat energy using one unit of electrical energy, making electric-powered space heating and cooling viable.
Even with the cost of solar electricity at all-time lows, solar thermal collectors are a viable way to heat water off-grid.
Though mainstream refrigerators have become more efficient, units like this SunDanzer are superinsulated and available in either AC or DC configurations, making them ideal for an off-grid energy budget.
The hardest part of cooking with a solar oven is getting into the habit of using it.
Induction cooktops waste less heat than resistance elements.
The Grundfos SQ Flex submersible pump is ideal for off-grid living as it can be powered by a variety of AC and DC voltages, and has a soft-start motor.
The efficiency and reliability of LEDs are perfect for off-grid lighting, but don’t overlook low-tech lighting solutions like daylighting from solar tubes and well-placed, high-performance windows.
The efficiency and reliability of LEDs are perfect for off-grid lighting, but don’t overlook low-tech lighting solutions like daylighting from solar tubes and well-placed, high-performance windows.
Though modern appliances are getting more efficient, sometimes the low-tech, low-energy (and old-fashioned) way is also the most efficient.
Modern portable electronics are often a more efficient solution than old-school components, and often provide a good excuse to upgrade.

Energy management is a key factor for successful off-grid living. I’ve been off-grid for more than 35 years, but this past year—2017—was my first with almost no generator use. I don’t have a large PV array—just under 1.7 kW peak. My two modest wind generators are great contributors, complementing the PV production. But the third crucial factor in my off-grid success is wisely choosing and using appliances.

It’s relatively easy to be off-grid if you have the budget for a large PV array and an auto-start generator—and if you don’t mind using fossil fuels. But many of us try to minimize our wasteful and nonrenewable energy use for environmental and financial reasons, and because it makes our lives simpler and more peaceful. Achieving an off-grid lifestyle that leans primarily on clean energy sources takes attention to the details of appliance purchase, implementation, and management. Each off-grid task has different possible solutions, and every off-gridder has different approaches. In this article, we’ll examine basic energy applications, and survey some longtime off-grid folks on their approaches.

Heating & Cooling

Heating and/or cooling is the largest energy load in most North American homes. When the climate and site lend themselves to capturing free solar energy, passive solar design—coupled with a well-insulated and -sealed building envelope—is still the pinnacle of solar efficiency. If a wide-open solar window is inaccessible at the home site, building a small, superinsulated house is still critical to energy efficiency.

For off-grid homes, burning wood is a common backup or primary heat source. The greenest path here is using selectively harvested wood from your local woodlot and burning it in an efficient masonry heater or EPA-certified woodstove. Common advice had been that electricity shouldn’t serve the heating need, but high-efficiency ductless minisplit heat pumps (MSHPs) are changing this. I recently had a 120 VAC MSHP installed at my off-grid home, though I can only use it in periods of good solar and wind system production. While it uses energy efficiently, it still consumes a lot of electricity—and I’m not willing to run a generator to power it. However, it has reduced my firewood usage substantially.

“Efficient Heating with Wood” by Stephen Hren in HP159
“Efficient Heating with Minisplit Heat Pumps” by Vaughan Woodruff in HP180

Comments (9)

NEKoffgrid's picture

Ian do you really still have a 1984 Sunfrost? Ours is from 2001 or so and still works fine (we've only replaced the door latches). We're about to build a new off-grid home and move, and wonder whether the $$ Sunfrost refrigerator is still a good option. We could go AC this time, but wonder whether the longer lifespan of the DC fridges (and slight savings in power by going DC) would make up for the initial higher cost. Also wondering whether the other DC models (Unique, Sunstar?, SunDanzer) will last a long time like the Sunfrost, as they all cost less.

Ian Woofenden's picture
Yes, my 1984 RF-16 is still working. Actually, the F is not working at the moment -- probably an electronics issue -- but I have two outside freezers and this problem hasn't risen on my priority list to fix. But the fridge has been great for 34 years now; yeah, new latches every several years until Larry got it right, and a few new thermostats.
Sun Frost is no longer making units, and it's not a simple question whether to go DC or not. I'd say that most new off-grid homes go AC, but I'd encourage you to be VERY careful in this purchase, since it could well be the largest single electricity user in your home (depending on how you heat and cool). Your energy generation profile might impact this decision. With sunshine and wind, I don't have many times without a surplus, or at least enough. If I were only PV, I'd go DC just to be more of an energy sipper in the dark times. I've been quite happy with my SunDanzer freezer, and would buy one of their units again in a heartbeat -- the machines and the people are great. It's hard to say if they'll last as long as my SF, but I think there's a good chance.
Best, Ian Woofenden, Home Power senior editor
Mr. Bruce Arkwright, Jr.'s picture

Do you not use a chest refrigerator in a humid/ semi humid area it only collects water at the bottom of the refrigerator!!!! It's a mold generator! I learned the hard way!

Neal Collier's picture

I agree with Fred, Ian, get some more modules! They are about the cheapest things in a system, these days. My boats have arrays as big or bigger than yours! And something to consider, let your electric boat tie into your main system to add PV and battery capacity.

My buddy, Stan-the-Hermit, is presently installing an additional 3200 watts of B panels he bought for well under a grand on our last trip to Miami. This will help him cut back on the expensive propane.

Back to the original subject, SOME of the MSHPs are incredibly efficient, though not all. Look for an inverter type and be sure to check the ratings and not go for the cheapest price. Note, too, that there are MSHPs that will run on DC or have an inverter section that can be directly wired to PV modules. Yup, an MSHP is on my horizon as my rickety SEER 13 heat pump falters, but in the meantime, I am wiring up a new inverter to run the old a/c by day, when not limited by my meager battery stack.

Ian Woofenden's picture
Hi Neal, See my comments to Fred. Adding PV is a great idea in many cases, and it is CHEAP compared to the old days. But there are weather conditions (maybe not in Florida) where adding more will not help the occasional seasonal energy deficit. Best, Ian
Tod duBois's picture

While I think articles like this are great and needed the first sentence of the first paragraph dismisses the reality of cost-effective off grid and I urge authors to use caution when making comments like "is relatively easy". What I think the author was saying is when you have a large budget and can pay professionals a lot of money and buy expensive equipment going off grid is easy, which is true. We see this often with the agenda of going "green" whatever the cost. One needs to think "green" and "greenbacks" go hand in hand. Optimization tools like Homer and direct comparison to grid costs in kwh are key to moving us from odd-ball off grid people to true green infrastructure. We need to learn to beat the grid in a straight up fight or we stay marginalized.

Ian Woofenden's picture
Hi Tod, The sentence in question says, " It’s relatively easy to be off-grid if you have the budget for a large PV array and an auto-start generator—and if you don’t mind using fossil fuels." You need the money up front! But you are buying 20-50 years of electricity prepaid, so it's no surprise that it's "expensive". See my other articles on off-grid living for many comments concluding that on-grid is usually a better option. This article is focused on off-grid loads, and not on comparing on-grid to off-grid. People choose to be off-grid for many reasons. Money is sometimes a factor, when line extension costs are high. But if the grid is there, it's rarely financially sensible to cut the cord. Best, Ian
Fred Golden's picture

There are $200 260 watt solar panels available. It would seem simple to install 4 of these panels and a $25 PWM controller to expand your solar system. That might save you from ever running the generator and save a few hours per month spent on maintenance and fueling it.

Also the heat pump needs unrestricted airflow. Shading it does not improve it's efficiently, causing it to draw in warmed discharge air makes it consume additional power. These new heat pumps can provide twice as much cooling per KW compared with window units.

Propane refrigerators consume huge amounts of power when compared to high efficiency 120 volt refrigerators. However the ice maker will use significant amount of power - if equipped with one.

Ian Woofenden's picture
Hi Fred, I'm not sure exactly what your comments are addressing --feel free to explain. Adding more PV capacity would NOT reduce my negligible generator usage. Adding more wind capacity _might_, but probably not. There are just a few times of year here with almost no sun and no wind. I had literally fewer than 8 hours of generator run time last year, and no maintenance time. Compared to my early years of thousands of hours, this is great! My MSHP pump is in a convenient, open, outside space. It is covered, but not closed in. Best, Ian
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