Sizing the Panels
We last left off by sizing our battery bank. Now it is time to size the solar panels.
This is probably the most critical part of the system. It is, after all, the thing that will charge your batteries! If we do not size it correctly, we will end up with dead batteries a lot of the time. If you are okay with that then fine. However, if you are running something that you consider to be of a critical nature, you will want to make sure that you have sized the panels.
But First, Some Things I Have Seen and Heard
As I have noted previously, I have been playing with solar panels for quite a while now. Since 2001, to be exact. I bring this up because I have seen and heard a lot of, well, let me be honest here, a lot of REALLY stupid things.
- We can’t use solar power because of where we live – we don’t get enough sunlight
- This panel that plugs into the cigarette lighter of my car is actually doing something useful
- I tried solar power and it was a waste of money and time
- You have to have some fancy contraption to point the panels at the sun
- That will never work
Taking these one at a time:
We can’t use solar power because of where we live – we don’t get enough sunlight
Nothing could be further from the truth on this one. Even on the cloudiest of days, my solar panels typically put out 75% of their rated capacity, and this is worse case! Solar panels are also used the world over, from deserts to the arctic. The trick here is to size the panels and batteries accordingly! Think about it. At the south pole, where it is dark 6 months out of the year, and light the other six months, you can easily use solar power. You just have to make sure that your battery bank is sized correctly to supply all your needs when it is dark. You also need to make sure that your panels are sized correctly so they can charge the battery bank when it is light. It does not matter what part of the globe you are on – you get daylight and you get darkness.
This panel that plugs into the cigarette lighter of my car is actually doing something useful
Yes, it is. It is providing enough power to keep the clock running. Maybe.
This is an instance of what I consider selling snake oil. Usually these panels are only putting out a few milliamps of current. This might be enough, as I noted, to keep the clock in the car running, but it is NOT enough to make any real difference.
I have seen people actually try to use these very small panels to power large things. Trust me, the power one of these puts out is not enough to even keep the battery supplied with a float voltage. People tend to want to rely on them for one reason and one reason only – they are cheap. The first thing you must realize is that doing solar right is not a cheap thing to do. Small panels like this DO have a use, but not in this case. If you are considering this method of powering lights and radios, you should stop reading now, as nothing in this document will help you.
I tried solar power and it was a waste of money and time
I hate to say it, but obviously you were not doing solar properly! Yes, solar power is expensive. It is very expensive when compared to using electricity from the grid. Currently in my area, electricity is delivered at the rate of around 14 cents for every 1000 watts. A solar system like I have built has cost me close to the $7.50 a watt range. That is a huge difference! However, my goal is to be able to be without grid power for many many days and still operate my amateur radio station.
But another thing to think about is life of the panels. I spend $7.50 a watt up front. That panel will be able to generate power whenever it is daylight for the next 30+ years. Some of the first panels that were manufactured in the early 1970s are still going strong today.
So, yes it is expensive up front, and the return on investment is a long way off. But being able to have electricity any time without the need for to rely on an outside source far outweighs the price in my situation.
You have to have some fancy contraption to point the panels at the sun
No, you do not. You could come up with something to do this if you wanted, and you can spend lots of money doing it. You will see a benefit by way of higher output from the panels if they are pointed directly at the sun, but you will also be generating power even if they are stationary. The cost of these pointing devices is quite high. There are times when you would want to employ a device such as this, but the system I am using is not one of these cases.
That will never work
It sure does! As I noted, I have been using solar power for quite a while now. I have never run out of power. I live in a location where I was told “we can’t use solar power in this part of the country because we don’t have enough daylight.” I was told I had to have “some fancy contraption to keep the panels pointed at the sun.” And I have been told time and time again “that will never work.” Yet it does. And very reliably, I might add.