Having been living with our solar power now for over a year (installed Sep 2016), I thought I might share a few of the things we’ve learned over the passed year living with it.
I guess one of the first questions people wonder about, for our area, would be “is it worth it?” This question does have several dependencies, but overall, I would say definitely YES! The more we hear about how the cost of grid electricity is going up and up, we are so glad we aren’t part of that. Especially up here where power outages are not uncommon. We never notice when this happens.
The other fun thing, especially during the summer, is that you can use as much power as you want during the day. In fact, this is recommended as this is when the sun is up and your batteries are being charged. Compare that to being on the grid (here in Ontario anyway) where they charge you extra for the power you use during “peak hours”. This always felt like being penalized for working from home.
Of course, whether it is worth it for you will depend heavily on how you expect to use it. Power used is based on energy and time (thus why your electric bill is charged by the kilowatt-hour). If you want to do a lot of work in a short amount of time, you will need a lot of energy. Anyone considering going off-grid should take some time to do some research. Figure out what things you are using right now, what appliances, kitchen gadgets, bathroom widgets, computers, TVs and so on. After you have that list, figure out how long you use each of those items everyday. Add all that up and you’ll get a rough idea of your daily use.
As a heads up, anything that uses electricity to generate heat will be a fairly big power draw. Hair dryers, hair curlers, hair straighteners, hair crimpers, space heaters, electric stoves, electric clothes dryers, toasters, electric waffle irons, clothes irons, soldering irons, electric welders… (you get the idea) will all draw a lot of energy. I put that in bold because how much power they draw will depend on how long they are used for. Unfortunately, most of all of those things I just listed have a long warm-up period before you actually start using it, so that will add to the time. Something like a microwave, which does draw a lot of energy, but it doesn’t have a warm-up time, can work to your benefit. Generally speaking, how long do you really run your microwave? Usually under 5 min. It may have a high energy draw, but it is a short amount of time. Compare that with something like a slow cooker, which draws less energy, but is used for long periods of time and you may find the slow cooker kills your off-grid system. If you can’t live without your slow cooker, we highly recommend a thermal cooker instead.
When we moved up here to the trailer, we knew we would be going off-grid so we did the tough thing and got rid of all of our electric based heating devices. This included a really nice toaster oven we had, which was difficult to give up at the time. Now we don’t even think about it. We only have three solar panels at 250W each so our system isn’t huge. That being said, the seasons affect it big time.
From March until October, everything is golden. We get enough power to handle all of our needs without having to resort to using a generator as back up. This includes things like power tools and vacuums that draw a lot of power. For that stuff, we usually just wait for a sunny period.
From November to February, in this part of the world, it is cloudy more often than it is sunny. Also, the days are a lot shorter, so even when the sun is out, you don’t get a lot of time to recharge the batteries. Additionally, if your batteries aren’t kept in a temperature stable environment (ours are out in the cold), this will impose further energy loss to you for usage as it will take more energy to charge the batteries when they get cold. This is where having a generator as backup is necessary.
We have a little control unit with an LCD display attached to our inverter that tells us various things.
In the above picture you can see that we are in Bulk Charging mode and we have an input voltage coming from the batteries at 58.0V. If the inverter is telling you it is charging that can only mean one thing: the generator is running. When the generator isn’t running, we just have a read-out of what the voltage is coming from the batteries. There are other things we can check, but I find the voltage is the most useful. We have a 48V system and having lived with it for over a year now, I have a pretty good idea of how full the batteries are based on the incoming voltage.
If that 58.0V I mentioned above seems high, it’s not. Think of your batteries like a car tire. If your tire is full at 30psi (around 207kPa) then you will need a compressor that can generate more than 30psi to fill that tire. That’s just the nature of the physics. In addition to that, as far as the batteries are concerned, the colder it is, the more voltage (electrical pressure) you will need to fill the batteries. During the summer, we can top out the batteries at 57V, but during the winter, we can push it up to 62V before they are filled. The charge controller we have handles this automatically using temperature compensation.
Incidentally, that increase in voltage when it is cold comes with one interesting factor: the resistance in the wires drops as it gets colder, so you gain some extra voltage in the winter. If you can keep your batteries somewhere more temperature stable (like a garage), that would help a lot. Lead acid batteries don’t like it when they are cold.
There are other battery options, some of them are quite new and I would be fascinated to try them (e.g. the Tesla Powerwall), but they can also be more expensive. Depending on the added advantages (e.g. no maintenance, higher power storage), the extra cost may be worth it.
The things we mainly use our power for are the lights in the trailer, our laptops and charging our phones. Sometimes we’ll use a blender or hand mixer, but it’s definitely not every day. We don’t run any of the big power tools during the winter, as the shop isn’t heated and it’s not fun trying to build stuff when your hands are freezing. During the warmer months we do run a miter saw, table saw, electric planer, skill saw, compressor and a few other things. All of those have a big draw when they start up. The miter saw draws between 1100-1200W while it is running, but how long does it take you to make a cut: 5 seconds or less for most things so the energy usage is fairly small per cut.
I can’t say I was an expert going into the whole solar power thing, but I had done some research and I did have some classes on it when I did the Earthship Academy. I knew enough so when I went to talk to the guy at Solar Depot, I wasn’t a complete noob. I’m not an electrician, and I didn’t wire the thing together, but I do have a pretty good grasp on how to monitor it and maintain it.
In the end, if you can figure out what your needs are, do a bit of math, you can figure out what size of system you are going to need. That being said, you could build a system so huge that you could run just about anything. However if the cost of your system is so high that you will never recoup the loss, when compared to being on-grid, then there isn’t much point. If you can cut back on your usage so the cost of your power system is reduced, it can definitely pay for itself within a year or so.