Members Are Now Enjoying Solar Powered RC Flying at the Sky Knight Field!

By Gregg Marshall

The idea of a solar panel came from an article published in the December 2009 issue of Model Aviation. It spoke of an AMA club in Arizona who had designed and built a similar charging station. At the time, I, like many who are first entering the hobby, was flying predominantly electric airplanes and mostly park flyers. I had read all the online posts and heard the guys at the club discuss the dangers of Lipo batteries. I had even seen a demonstration of how easily the modern lipo could catch fire fairly quickly.

Wanting to be flying and not charging, I had accumulated several batteries which would allow me to fly constantly while depleted batteries charged. At first I designed a charging station that would plug into the outlet used for towing my RV. That worked well for some time. But I kept breaking the connection. Which led me to just plug my chargers directly to my vehicle battery. The issue here was that they were charging on the front of my hood-raised pick-up truck. Meaning if I did do something wrong, the potential of frying my electrical system or merely lighting my truck on fire was high.

Every time I connected my charger to my truck battery, I was reminded of the article back in December. I also began to notice that the members who fly glow were lugging big, heavy deep cycle or car batteries. Even if not far from their work table, this could be work for many of the older members. Then it happened! No, I didn’t short the truck or catch it on fire. I used it so much I drained the battery enough to require a jump. That was the final straw. So I approached the Executive Board with the idea of the solar charging station on the premise it would not cost the club or membership.

So I began to research the whole concept. I started by re-visiting the AMA article, reading posts on the web forums and in depth Internet searches. There were various thoughts on the requirements but nothing seemed to stand as a solid foundation to designing an appropriate site. Mike McKay and I attended the solar expo at the Oregon Convention Center in hopes of gathering the right information and maybe even get a volunteer to help. That bore absolutely no fruit. We seemed to already have a knowledge base beyond those exhibiting.

While gathering the necessary information to design a site, I began requesting cash donation from various organizations. Requesting donations was difficult only in the sense I had no idea what the final numbers would be to cash flow the project. The first donor was Stephanie’s Café in Sandy, Oregon. Actually, it was Stephanie’s eagerness to donate that led to me really launch the project. In addition to Stephanie’s Café, other local businesses we equally as eager, including Mt Hood Theater, Corban Technologies and RC Hobbies in Portland .

Around the same time, a new business opened in Sandy, Energy Unlimited, which is a residential solar provider. I contacted them and laid out what our needs were. The goal was to be able to charge approximately forty 3000MaH batteries over the period of a day and not take longer than 2 days to recover. Once the necessary equipment was decided, Energy Unlimited put together the list of other parts needed to complete the project. They also allowed the club to purchase all of the parts at their cost. The order was placed for a 175 watt panel from Solar Nation along with a charge controller that would allow monitoring of the panel input voltage, battery voltage and draw.

While the necessary components of the solar charger was being determined, there were various discussions on how to mount the solar panel. Thought was given to safety, theft and vandalism, mobility, location, etc. After many iterations, Sam Bacon volunteered to design a four post shelter with a pitch roof. Before construction began, the roof was changed to a slant roof to provide greater visibility and surface area to be able to add more panels in the future. In June, the shelter took shape and in early July the panel was installed. Paul LaPlante donated two large deep cycle batteries which is charged by the panel and provide the charge to the chargers. Ultimately Sam paid for all of the supplies to build the shelter (click on photos for larger image).

As the 2010 season has wound down, I am very pleased with the results of the charging station. At no time during the season did we ever get close to draining the source batteries. At a late season training night, we had 10 chargers connected charging 20 batteries simultaneously and the lowest voltage recorded on the source batteries was 11.8 volts. That is an outstanding result.

As with many projects, there was an unattended consequence. Not only does the shelter support the solar charging station, it has become the central gathering place of those utilizing the field. It has also spurred thought of adding other shelters for various reasons. It seems to have provided a unification point and an alternate energy within the club. I am looking forward to the seeing what the Solar Charging station is capable of next season.