By Steve Smith
A small, affordable solar power system for your off-grid cabin. This article is for the beginner with little knowledge of the subject.
I am not an electrician. In fact, I have pretty much zero experience in electrical work other than when we designed and installed a solar power system for the camp house at the ranch. Before we finished the cabin, I began researching the subject online and I must say, after reading many articles and watching many YouTube videos I thought my head was going to explode! Through the process, I have managed to simplify it down to a manageable concept and cut through much of the technical clutter.
Please note that I am not an electrician and far from an expert on the subject. You should take safety measures and seek the advice of professionals to avoid danger. The electricity at the camp house has been intact for about three years now and we haven't had any mishaps and it has worked very well. As far as safety, danger, and liability is concerned you have been warned that I am no expert, so you are indeed on your own; that said, this has worked well for me. I recommend that you do a lot of research on the subject, ask other people who know about electrical and be very careful.
The Basic Concept
I found it easier to think of the solar electrical system like a horse water trough with a hose going into it. The trough is the battery, the water is the electricity, the horse drinking the water is the load or what you are using the energy to power, and the garden hose is the electricity coming into the battery from the sun and solar panel. You want to keep the garden hose turned on just enough to keep the trough water level relatively constant while the horses are drinking and to stop flowing when the trough is full.
The goal is to find the right mix of batteries, solar panels, and power consumption to keep the battery almost full at all times. Draining the batteries down and recharging them over and over again diminishes the life of the cells.
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| 2 100W Solar Panels |
Be Realistic
When I was dreaming up our power system, I imagined running a small window unit, coffee maker, small refrigerator, lights and several wall plugs. We've had the ranch since 2005 and never had power and really never missed it. We seldom used the generator for that matter. We used Coleman lanterns for light. The only electricity we actually need is lights, wall plugs for phone chargers and maybe a small fan.
We planned to have a light in the middle of the central living area, a light over the kitchen prep area and another above the table where we eat. We have since added a bedroom with a light and two wall plugs as well as a back porch with the same. On the back porch, we put one outlet down low near the doorway and one up high and in a corner so that we could energize string lights.
The Basic Components To Get Started
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| 30A Charge Controller |
There are many directions you can go but here are my recommendations based on my experience.
Amazon proved to be the best resource for procuring supplies. The $10 Prime membership will save you a bundle on shipping. I highly recommend that you NOT shop Harbor Freight for SOLAR COMPONENTS.
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The wire coming in from the solar panels to the
charge controller on the wall and then to the batteries. |
COMPONENTS:
1 or more 100W solar panel ($120-$150)
1- 750W or higher power inverter ($50-$125)
1 (or more) deep cycle battery ($100)
1 30 amp charge controller ($35)
Heavy gauge wire from the solar panel to the charge controller and from the charge controller to the battery
Wiring the cabin
To wire the structure, do so as you would any house for the light fixtures, wall plugs, switches, etc. If you want the safety and status of including breakers and what not, do so. If you are like me and not so savvy regarding residential electrical, try thinking of your lights and outlets as a big set of Christmas lights, or an extension cord. Imagine the light string or extension cord has outlets and switches in the line and has a regular household male wall plug on one end that will be plugged into the inverter receptacle, which will energize the run. I turn off the inverter when I leave which turns off the power to the system. I created two circuits and put wall plugs on the ends and plugged them into the two available receptacles on the inverter as if the wiring, light fixtures, and wall outlets were just a big, homemade extension cord.
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Power inverter-Inside of the cabin- Black plug is connected to the wiring of the house
that has the lights and wall outlets. The red/black lines go through the wall
and outside and are connected directly to the batteries. |
Setting up the system
Once all your wire has been pulled and you have planned out where your light fixtures, power outlets, and switches will go, install your power inverter in a place that makes sense, keeping in mind that you will be connecting the wiring circuits to the inverter. On the other side of the inverter, there will be the posts, to which you connect the wires, that go to the 12V batteries. The way I did mine is I put the inverter on the inside of the cabin and drilled a hole in the wall leading to the outside. I ran the large gauge cable from the inverter, through the hole to the outside, down the wall and connected to my 12V batteries. I then mounted the charge controller to the outside of the cabin (see photos) and ran wiring from the charge controller to the batteries and then ran wires from the charge controller to the solar panels. The charge controller has wire receptacles for the solar panels and for the batteries.
So, the sun hits the panels sending a trickle charge into the charge controller, the charge controller evaluates how charged up the batteries are and shuts off the charging of the batteries once they are full to prevent damaging them. From the charge controller, the power goes into the batteries (until they are fully charged). The batteries are connected to the inverter and the lights and outlets are plugged into the other side of the inverter. Of course, the inverter changes the electricity from the batteries into regular household power. It's a bit unconventional but straightforward (once you get your head around it) and as long as you are very careful and keep it turned off when not in use it seems to be pretty effective and safe. I have had no problems in the last 3 years of semi-regular use.
Recap/summary:
Solar panels (facing south)- wires from the solar panels go to the charge controller.
Another set (pos./neg) of the same kind of wire goes from the charge controller (little black box mounted on the outside wall) to the batteries.
Larger wires (pos/neg) go from the batteries (which are being charged by the solar panels and monitored by the charge controller) through the wall, into the cabin and connect to the positive and negative posts on the power inverter.
The house wiring has a regular male household plug on the end that plugs into the inverter, which energizes the line giving power to the outlets and light fixtures. On/off switches are placed before the lights so they can be turned on and off as per your needs.
By Steve Smith
