It’s time to talk about using electricity in an Earthship. From the title you can probably surmise that this is about using solar and wind to generate electricity, and you would be correct.
I should add here that renewable energy sources, in general, are what is desired. If you live on the coast and can harness tidal power, that is equivalent to what I’m going to talk about here. Similarly, micro hydro and geothermal would also fall under this category. Solar and wind just happen to be the two most common renewable energy sources.
The vast majority of people these days are familiar with solar panels and wind turbines, at least to a point where they understand that they can be used to generate electricity. There are a number of details to be aware of.
First and foremost, as mentioned before in other posts, an Earthship is designed to be independent. That means not connected to an electrical grid. This independence arose from the basic principle of wanting to create a building that could be built anywhere in the world, regardless of available infrastructure. The advantage to this is that if the grid goes down, you aren’t affected. Conversely, if you have issues with your electricity, you aren’t affecting anyone else. Considering how many times a year we have weather that knocks out the power grid, this can be a big advantage.
Once you start down the path of generating your own power, you need to take on a certain amount of responsibility for that. After all, when something goes wrong you are the one who will have to deal with it. There are some companies that will sell you all of the equipment and hook it all up for you. If something goes wrong you can call them, but you should be aware of what you are buying and what you are getting yourself into. It just makes sense if you want to get the most out of generating your own power.
Solar power is pretty ubiquitous these days. If you are interested in solar, some basic things you should research are: the average number of sun hours per year in your area (called insolation), what your power requirements are, what kind of sun-based view you have available to you and what type of system you are looking for.
When generating your own power, you have basically three options in terms of how to set it up: completely disconnected from the existing electrical grid, grid- tied and a hybrid of the two. Off-grid is pretty self explanatory: you are not connected to the existing electrical grid at all. In the case of being grid-tied, this means that all of the power you are generating is being fed directly back into the grid; you aren’t using any of it yourself. The electrical company pays you for the power you generate and this shows up as rebates or credits on your existing utility bill. The advantage to this is you don’t ever have to worry about using too much power. The downside is, if the grid goes down, so do you. It could be a beautifully sunny day, but if the grid is down, you have no power and you aren’t getting paid for all that power the solar panels are generating because the grid is offline.
A hybrid system is where you have battery backup and if the grid goes down, you still have whatever power you have stored in your batteries to use. It seems like the best of both worlds, but this is also the most expensive way to do it as you need more hardware to handle it all. You also need to have a grid line close by to tap into.
Solar panels come in lots of sizes and power ratings. You should probably aim for getting enough panels to generate a little more than double the power that you plan to use on a daily basis. This will help to compensate for cloudy days.
Wind turbines are a whole different ball game. I don’t have any personal experience with my own turbine, but I have done a fair amount of research and talked with those who have tried it. My biggest piece of advice to anyone wanting to try out wind power is to live on the property where you are planning to install it for at least three years (probably five is better) before getting a system. This will give you some idea as to what the wind is like over many seasons. As always, there are exceptions, such as if you live in a coastal region or the prairies where it is windy all the time then you probably don’t have much to worry about. But in areas like where we live (forested hills) wind is hard to come by a lot of the time. Most of the people I have talked to in the area, including some who have turbines, say it’s not really worth it in our area.
Some other things to consider with wind turbines is that they are motors in motion and as a result of that, they will wear out and break. Solar panels have no moving parts so they don’t have that problem. Also, there will be times when there isn’t enough wind to turn the blades as well as times during storms when there is too much wind and it may destroy your turbine. Remember this if you are in tornado alley.
The vast majority of wind turbines are the horizontal axis kind. Those are the ones with the blades all facing into the wind, like in the picture below.
These are generally speaking the most efficient, because their blades are facing directly into the wind. They also get the most wear and when really strong winds come up, most susceptible to damage.
The main other type is the vertical axis wind turbine. Here is a picture of one they have at Earthship Biotecture in Taos, NM.
These ones are less efficient in terms of the amount of wind the blades capture, as only one side of the axis catches the wind and the other pushes against it. There are lots of online articles about them and I’m sure the technology has changed over time, but this type of turbine are favored by Mike Reynolds. According to him, they take less wind to start turning, don’t spin as fast in strong wind because of that push back effect and last longer without needing repairs. If this is true, then if you amortize the average power generation over time between a vertical and horizontal axis turbine, taking into account down time for repairs, you might come out ahead with the vertical axis turbine simply due to the fact that it doesn’t break as often.
Of course, no discussion of off-grid living would be complete without talking about batteries. Your basic battery used for power storage for an off-grid home is the lead-acid battery. These are the same type used in golf carts and marine settings (boats). These are the cheapest, but by no means are they bad. They do require maintenance, however. You need to keep them topped up with distilled water as the electrical reactions use up the liquid over time. I do our battery maintenance once a month.
You can get sealed batteries and they have gel batteries as well. You may have heard about the company Tesla coming out with a battery solution of their own using Lithium-Ion batteries (the same type in your phone). I have looked into this somewhat as it seemed like a nifty thing, but it turned out to be not as nice as I would have hoped. First, it is not just a battery, as it includes a built-in charge controller, inverter and computer to control the whole thing. This isn’t very convenient if you already have an inverter and charge controller. The system is meant more for a backup/hybrid grid-tied setup. Also, it requires a connection to the internet to function (so they can give you over-the-air updates and monitor your usage). Ummm, no thank you.
There are other options out there as lots of companies are working on battery technology. In the end, it usually boils down to what you are looking for, what is available and what you can afford.
These are all the types of things you get into when you start thinking about going off-grid. For some people it is very interesting and they jump right in. However, there are many others who don’t want to be bothered with it all and just want power when they flip on the switch. Personally, I like knowing how much power we’re making and using and we manage our usage to match what we make.
We have been running our solar off-grid system now for over two years and we love it. We do have a generator as a backup for those long stretches of cloudy days during winter. We wouldn’t need it as much if we added more panels to our system. That will happen eventually when we get our Earthship up and running.
I do apologize for this article taking so long. I have worked on it several times, but it was degrading into long descriptions of Volts, Amps and Watts and I was trying to keep it a little simpler. If you do have any questions about this, feel free to leave a comment.