The first thing to remember is that solar is not cheap! The power itself is free and sustainable, but getting there costs money. You can spend as much as you want chasing a bigger system. I didn’t go whole hog on mine – I mainly wanted to power a few appliances and recharge my rechargeable batteries.
I have a couple of systems set up in different locations, as well as the ability to set up portable arrays. My main array consists of:
- 4 – 85 watt panels & a 30 watt panel.
- These run to a 21 amp ICP charge regulator/controller, and then to a bank of 8 – 12v deep cycle marine batteries.
- Tied to that I have a 2,000 watt power inverter for the 110 household current, as well as 2 – 12v cigarette lighter type sockets to have the ability to run 12v appliances if needed.
I have a problem with this system: I really hate to cut trees, since you can’t replace them in your lifetime. So my system doesn’t get full sun all day. It gets about two-thirds of what it could get, but that meets my anticipated needs. It will power a small freezer, a portable ice maker, a 110v chain saw, and many other items like that.
I have a secondary array at a nearby building that isn’t used to its full potential, but it serves as a backup system.
It consists of:
- 1- 85 watt panel, and
- 2 – 50 watt folding panels that run to another charge regulator/controller and
- only 2 – 12v deep cycle batteries.
- This then runs to another 2,000 watt inverter that is actually a backup in case of a failure of my primary unit.
The panels on this array can plug into the main array using polarized two-way plugs. That makes it modular, so I can add power to the main system as needed.
At my pond I have a shelter house on which I mounted:
- a 30 watt solar panel that runs to
- a smaller charge regulator/controller and then only
- 1 – 12v deep cycle battery
- This runs out to 12v lights in the ceiling of the shelter house, as well as a couple of cigarette lighter 12v outlets.
I can plug in a 400 watt inverter to the 12v system and power most small appliances that I might have there.
Last but not least, I have several smaller panel setups that are extremely portable and powerful. They can provide 12v power just about anywhere that has sun exposure.
Here’s how to build a DIY solar power system, starting with the basic components you need:
1. Solar Panels
First you have the solar panel. This is what generates electricity from sunlight or even artificial light. They come in many sizes, types, prices, and wattages. Power coming from the cell to charge a battery needs a diode in the circuit. Without one, the battery can discharge back through the panel when there’s no power coming in, since the current will flow backward.
Think of it as a one-way valve. Some panels, like the Volkswagen units, have the diode built in. Otherwise it’s built into the charge regulator/controller, if your system uses one.
2. Charge Controllers
Second, if you’re putting together a larger array of permanently mounted panels, you’ll need a charge regulator/controller. It controls the charge rate from the solar panels so you don’t overcook your batteries. These also come in various sizes, types, and prices.
The key thing to remember is that the wattage here must be larger than the total wattage of your panels. I made the mistake more than once – thinking my system would stay a certain size, then having to buy a larger controller once I expanded it. So buy big in the beginning, and you won’t have to buy again later.
3. Batteries
Third, the batteries. The best batteries to use are the deep cycle batteries commonly used in golf carts. But they’re very pricey, heavy, and not easy to find in some places. They usually have to be special-ordered in rural areas like where I live. So I opted for the biggest marine-type deep cycle batteries instead. Though not cheap either by any means, you get what you pay for.
You now have a system that produces and stores 12v power. There are two things you can do with it in this form: hook up an inverter to change the power to 110 volts, or use it as-is at 12 volts.
One update worth knowing if you’re building a system today: lithium iron phosphate (LiFePO4) batteries have become the standard recommendation for off-grid solar in the years since this setup was built. They cost more upfront than lead-acid deep-cycle or marine batteries, but they’re lighter, handle far more charge cycles, and tolerate deeper discharge without damage – which often makes them cheaper over the system’s full lifetime. The lead-acid deep-cycle and marine batteries described above still work fine and remain the cheaper upfront option, but if you’re starting from scratch, it’s worth pricing out LiFePO4 before you commit.
4. Inverters
If you’re using an inverter, here are some things to consider. They come in various sizes, types, and of course, prices. In the most common types, there’s pure sine wave and modified sine wave.
Pure sine wave is more expensive, but modified sine wave is fine for most normal use. If you want a technical explanation of what that means, you can Google it. But simply put, some sensitive electronics require pure sine wave, whereas most will work fine on modified sine wave.
Inverters are rated by wattage, and they’ll show two different numbers. One is the normal usage wattage, and the other is the surge wattage. Some appliances use a bit more power as they start, but level out at a lower wattage as they run. That’s what the surge rating is about.
It’s important to understand how much wattage you’ll need to run the appliance you want to use. There’s a plug-in device called a “Kill A Watt” that runs about $30. Plug it into the wall, then plug your appliance into it, and it’ll tell you exactly how much electricity that appliance uses. It can be an eye-opener in some cases!
Almost all inverters have overload protection and low voltage protection. They’ll auto shut off, sometimes with a small alarm, when over or under loaded.
Buying a quality name brand here is important. I got stung a couple of times with cheap off-brand units that were rated higher than they actually worked. You usually get what you pay for here as well.
What Size DIY Solar Power System Do You Need?
I started out very small and worked up. There are those who power a whole house with their setup, but that’s very expensive and complicated. Plus the upkeep isn’t cheap. A smaller system will serve most emergency needs.
I have noticed the Amish in my area use solar power to run their cash registers at their small stores. They also have little outside phone buildings with solar power to charge the batteries for the fiber optics used in the phone lines. These are all single, small solar panels.
Is Solar Power Worth It To You?
As I mentioned in the beginning, this stuff isn’t cheap. I built it up over a long period of time, so the cost became more affordable. I started very small: a couple of Volkswagen solar cells, a plastic battery box with a built-in 12v lighter socket and external terminals, and of course a deep cycle battery. I added a splitter to that setup, which let me plug in multiple lighter sockets for panels or for power out.
I will post in the future some do’s and don’ts, as well as some tips for use. There’s much to know about solar, but it isn’t as complicated as most people might think – not for the smaller setups like mine.