My Off-Grid Solar-Powered Air Conditioner

Reader Contribution by Cam Mather
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I always thought “air conditioning” and “off the grid” didn’t belong in the same sentence, unless it was suggesting that you COULDN’T have air conditioning off the grid. But like so many things in my life I have discovered that foundations can shift and reality can be altered.

Since moving to our off-grid home 13 years ago we have suffered through heat waves. I am not one of those people who like the heat. I love winter. I love being cold. In the winter I can just keep adding layers until I am warm. I find heat inescapable and debilitating. Of course you can’t grow food in the winter, so summer seems like a pretty essential season. But that doesn’t mean I have to like it.

I suppose if I lived in a city and had an air conditioned house, and office, and car, and didn’t have to grow food during droughts, I’d probably love summer too. But summer just wears me out. Early on in a heat wave I can still function, but after a few days I start dragging more and more. First I lose my appetite, which isn’t a good thing because I’m still burning calories working in the garden. Heat waves are usually accompanied by a drought so watering the gardening becomes a full time job. I’m in the garden by 6 a.m. but I usually can’t work much past 11 a.m. and so I have to wait until after dinner to finish up.

I think what wears me down the most is not sleeping. I end up sleeping on the couch on the main floor, which is usually cooler than my second floor bedroom, but it’s never a restful sleep. So after a few days of not eating properly and not sleeping, I feel like a dirt bag.

As I’ve described before, we have a solar domestic hot water heater that produces more than enough hot water for us at this time of year, especially since we often swim in a local lake during a heat wave, and we aren’t particularly anxious to have hot showers or baths. We also have the diversion load dumping excess electricity into a second hot water tank. So a few days into a heat wave when we are making lots of hot water and not using much, it gets scalding hot. And since these two hot water tanks are in our bedroom, they help to heat up the room just a bit more to make it really uncomfortable for sleeping. Yes, I know, what am I doing with hot water tanks in my bedroom?

Turns out when they built the house in 1888 they hadn’t considered solar domestic hot water heating. Well, they hadn’t actually even considered inside plumbing, so the only way I could configure the system was to put the tanks in the bedroom. Michelle has written blog posts about what she thinks of them. It ain’t pretty, but it works.

So this summer I said “enough!”I bought a 5,000 BTU “Haier” window air conditioner. And it’s working great! It’s helping to make this heat wave, which is unbelievably brutal and relentless and unending, seem tolerable. I’m not eating enough and I’m spending way too much time in that relentless heat trying to grow food, but at least I’m sleeping. I have a refuge.  

I keep kidding Michelle that we need to start eating dinner in our bedroom.

I did not approach this purchase lightly. I realize that the HFCFCs or whatever the chemical that replaced CFCs is better, but not perfect. But it was $100 and it’s making a world of difference. It draws about 500 Watts of power. When the sun is out my solar panels are making over 1,500 Watts, so it’s using about 1/3 of my output. So I’m running all my other loads, including the water pump, which is going full time, and still have enough to run the air conditioner. I am not using the “dump” or “diversion” hot water heater very much, so our water is just very hot, rather than scalding.

Now Bill Kemp’s off-grid house has been air conditioned for a few years but Bill built an insanely efficient house, so I just assumed I was scuppered with one built in 1888. Bill recommended this unit to me and when he heard how well it was working he went out and got one. Here’s a quote from an email he just sent me.

“I was looking at how they managed to get so much cooling with so little energy. A very simple design takes the water removed from the air and pumps it over the condenser radiator (the hot part that blows the heat outside). The water dripping over it cools the unit as the fan blows the heat away. Same process as how the human body cools itself. Funny that no one thought of this until recently???”

This is what I love about knowing Bill. He buys stuff and takes it apart to see how it works. His wife Lorraine calls it “MacGyvering” stuff. But then when he figures out how it works he can describe it with analogies that I understand.. i.e. the air conditioner works just like you sweating. Now that I can get.

When we first started using it Michelle commented that it couldn’t be dehumidifying the air because it didn’t drip water out the back like all of the other AC units we’ve seen in action.

So the heat wave continues and I am getting a reasonable amount of sleep. My grass is brown. Any plant that doesn’t produce food is in crisis and is not getting any water. Trees are dying. Toronto, which usually gets 74 mm of rain in July, has had 4 mm. My gardens are crying out for rain. All I can give them is well water from the house and drip-irrigated water from the dug well in the vegetable garden. But all my food crops are doing OK. You can tell that at a certain point a lot of activity in plants shuts down when it gets too hot. They just can’t function properly. I’m hoping for a bumper crop of “tropical” sweet potatoes and peppers and all my heat loving plants. There has to be some upside to these summers.

And thanks to my “off grid, solar powered, pretty environmentally friendly and efficient air conditioner,” my personal “feeling like a ‘dirt-bag’ factor” has been remarkably reduced. And all off-grid! Who’d have thunk it! What next? Maybe an electric car I charge off the system! The skies are the limit now!

Photo by Cam Mather.

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