The Basics of Solar Power
By Bobby Neal Winters
Last September, I started playing with solar power above the level of the single solar cell. I’d played with solar cells which only generate a little current--it doesn’t hurt to think of them as a single AA battery--but there was just not much that I could do with one. I wanted to go bigger, to produce more power, so I invested in a solar panel.
Here I want to make sure that I am talking to readers who know as little as I did when I started. A solar cell is the basic unit that can produce electricity from the sun and I suppose is a solar panel technically, but when I use the word solar panel, I am thinking of something that has multiple solar cells connected within it. It is something with more oomph. I am thinking of something like what you see here. This is something that can produce 12 volts and can be used to charge a car battery. And in the approach I’ve been following, that is the point of it: charging a battery.
I started out buying the kit you see here along with the power inverter you see here. Let me explain how this works.
You may have gotten to this page by searching solar power, and that’s great, but in thinking about how it all works it helps to think about battery power. In my applications, I will not be thinking about generation power and selling it back to the power company to lower my bill. I don’t have enough money to invest in that. I am interested in having power in places that aren’t hooked up to the electric company. This means that I need to work from stored energy; hence, I need battery.
You may recall that batteries produce direct current (DC) and that many of the appliances that you want to use require alternating current (AC). The inverter is a device that converts DC to AC. You can buy a car battery, hook it to a power inverter, and it will run a box fan or an electric light, or just about [more later on just about] anything that uses AC until the battery is discharged too much. Car batteries are made to be discharged and then recharged. This is where the solar panel comes in.
Solar panels use sunlight to generate a current. That current can be used to charge a battery. Here is where we get a little fancy. I suppose you could use a solar panel to charge a battery directly, but in doing so you risk overcharging which I am told could damage the battery or cause a fire or make something else unpleasant happen. Therefore, you put a controller in the circuit to keep your battery from overcharging.
So the basic idea is to hook the solar panel to the controller, hook the controller to the battery, and hook the battery to the inverter. Then you can plug your appliances into the inverter which will be equipped with outlets.
I got this all set up and it worked great. It worked great until I plugged something into the inverter that was beyond its rating (400w) and fried it. You might think that fuses are supposed to stop that, and they are, but they didn’t. I had to buy a new inverter.
This being experimental, I didn’t proceed in the most orderly way. When you go to Youtube, you can see some very inspiring, very organized, very professional, and sometimes very anal-retentive makers. That is not the way I roll during the learning phase. I basically just strung the stuff together with most of the parts laying on the ground.
Just a hint: you really shouldn’t do that. Sometime during the winter, something got into my controller and messed up the LCD display. Evidently it kept on running because the night light I’d plugged into it kept going, but I became worried that it might catch on fire and burn my wife’s greenhouse down. To prevent this, I bought a replacement controller. Instead of getting the exact same controller, I bought this one because Amazon recommended it.
After it arrived, I made the discovery that the inputs and outputs are smaller than on my original controller. I couldn’t just plug them in. This was frustrating, but as I was going to mount the controller on a board and put the board on a wall, I used this as an opportunity to Okie-engineer a way to
- Go from a larger size of wire to a smaller size of wire;
- Keep the strain off the cables and the controller; and
- Make it easier to remove and add pieces.
The result is pictured below:
I believe my Okie ancestors would be proud of this.
My next step will be to work a second battery into the circuit in order to increase my storage capacity. Then I will get a better inverter to handle higher loads.
This is all being done at the house next door which was a gift from my father-in-law to my wife. We use it mainly for storage, but we do have it hooked to the electric grid. Our use never exceeds the base cost of $15/month. My goal is to ultimately have the house be entirely solar, and save that $15/month cost.