Panel Used:
64W - 3.88A

Sunlight Energy
Mike, WB8VGE

My Solar System

Solar power is a lot more fun than I thought it would be. It’s also cheaper than it’s ever been. Since my wife and I do a lot of camping I wanted to have solar so we could take less batteries. But I couldn’t see building up a solar system just for a few weekends a month. So, I took some steps to make sure my power could be where I needed it, 24 hours a day.

Note: By clicking on any of the images you see you can get a closer look.

First the panel. There are a lot of panel types and sizes to chose from. Some have a glass coating, and are more efficient but glass breaks and it would be hard to take one like that camping. The other popular type is a little less efficient, but it’s slightly flexible and has a heavy rubbery covering making it close to impossible to break or scratch. Perfect for portable use.

On Field Day a friend of mine, Larry, WA7MSK, camped with us at the site. I started getting excited as he pulled out a 2.5 amp panel on a nice long extension cord and pointed it at the sun. Of course I was all over him with questions.

He showed me how the newer designs could handle a little shade on part of it without shutting the whole panel down as the older ones would. The newer ones have a bunch of smaller cells all in parallel with diodes to protect any shaded cells from drawing power from the sunlit ones. The current production goes down as it’s shaded, but that’s about all. Heat is something to think about when using a panel. It’s best to keep it from laying flat because of the heat build-up. It reduces the efficiency of the panel. When camping a simple dowel rod to prop it up is all that’s needed - and that lets you adjust the angle to the sun.

He proceeded to show me a meter panel he had built using a couple of digital volt meters. He had them wired up to display the battery voltage and the current to AND from the battery. So at night he could monitor the drain because the current would show a negative number and while charging during the day it would be a positive number. Without leaving his camper he could tell if it was time to move the panel by the current it was generating.

I eventually bought several of these at a hamfest for $10 each, and have seen them at the Frys Electronics stores for $15. Of course any metering system would work, but the digital ones do negative and an analog would have to be switched or diode protected if used in line with the battery and the loads.

I was hooked. It was affordable and looked like a lot of fun and useful too. So, off I went to the solar store. Actually, there aren’t many places that sell the panels, at least not at reasonable prices. You’ll find most of the best buys are from people working out of their homes or small businesses. One of the large panel manufacturers actually gave me a local contact - so they are a good source for dealers in your area. Try to stay away from the RV and camping dealers if you are looking for a good price. They usually include a lot more than you need as ‘package deals’.

The thought of not having enough power always (needlessly) worries me. So I picked a panel that turned out to be far more than I actually least with my current demands. Before selecting a panel you need to think over some points.

    1.How much sunshine do you get? Here in Arizona, no problem - the Yukon - a problem. (Of course, their panels will stay cooler)

    2. What is your total needs, current wise. Measure all of your gear for current drain individually. Think about your operating habits and calculate your current needs in total amp hours per day. Remember, transmitters might draw as much as 20 amps when running 100 watts on CW. Of course you are listening most of the time, and even at high speeds your key up 60% of the time.

    3. Determine your storage capability. I selected a gell cell deep cycle car battery. It doesn’t leak or put out much in the way of gases. But, gell cells have lower amp hour ratings than regular car batteries. Again, this is determined by your needs and sun shine amounts. Mine has a rating of 52 Amp Hours (AH) and is more than enough. It’s actually recharged on a sunny day by 11 AM because of my usage rates. I know people who have 1000+ AH arrays of batteries - and they can pretty much light their homes and run many small appliances.

Once you know your needs you’ll know what size panel and solar controller you’ll need. Actually, you should assume at least 50% more usage just in case. That should cover those cloudy days during any rainy season you might have in your area.

I custom built my mount for my roof to allow me to install and remove the panel easily so I can take it camping. We have a tent trailer and now we can get away with one battery for weeks at a time, and not run a noisy generator to bother other campers.

I used heavy gauge aluminum and pretty much built the complete mount on the fly. It turned out simple and somehow used every inch of metal I had bought for the job. As you can see, it slides in and out from the front allowing access without getting up on the roof. It took one day (in 107 degree heat) to build this mount.

To allow for fast connection I used a regular power plug assembly box and snap door, but I used a low current 220 type plug. It looks like a regular AC power plug, except the two flat pins are flipped so they line up with each other. These are also marked well so I could keep track of polarity easily.

From the box under the eave of the house I ran regular house wiring across the attic and down the wall of the shack. I use a finished shelf board to feed my coax through and in this case brought the lead from the outside out a hole in the board. I then mounted the solar controller to the board making it a nice neat installation.

The solar controller is a simple device that takes care of the battery and panel. It charges the battery during the day, stops charging when a certain voltage is reached, and stops until a lower voltage is reached. It then comes on again keeping the battery at it’s peak without boiling it. During the day I see the LED turn on and off regularly. The more drain I have the less time it’s on.

You select your controller by the amount of current your panel can generate. My panel is rated at 3.88 amps but I’ve seen it peak at almost 4.5 amps. Arizona sun I guess. This controller was $40. Information is in the side bar. Installing the controller couldn’t be easier. You have 4 screw terminals, two for the panel and two for the battery. Done.

As I mentioned before, I have two panel meters connected to the system at all times. These are cheaper meters that require their own power source, and can’t use the same battery it’s measuring. I can’t even share a battery between the two meters. However, a battery will last months and months, so it’s not a big deal.

The meters are wired such that the voltage meter is directly across the battery showing voltage at all times. The current meter was a little harder to install. What you have to do here is wire the meter for 200 mills at maximum reading. Then, figure out what size shunt to install. I ended up using a little chunk of the same wire as the house wiring. Turned out an inch was all it took. The current meter is in line with the battery lead and it’s BEFORE the solar controller or any load. This allows measurement of the current, both positive and negative at the battery. If I see -.5 I know I’m drawing 500 mills from the battery. The sun can be shining and I might have 2.5 amps going into the battery, but with the 500 mill load it would show 2 amps. This gives me a good feel for the current status of the loading and charging of the battery.

I have a few older tube type radios that I enjoy, and they obviously don’t run on my system. I do have a 24 hour a day packet system running off solar and an IC-706. From my calculations I could run that on receive 24 hours a day also with no worries. I also have an automatic antenna tuner and some fans that run from the 12 volts. It’s very easy to run any of my QRP gear from it and I have plans to add some 12 volt lighting to the shack. DC lighting is probably a little quieter too.

If you have any questions please feel free to send me some e-mail at .


Dave, AI7R