Solar Panels at Sea

Tonya Ricketts and Captain Dave Pickering 

Among all the advances in power technology for boaters, one of the most popular is adding a solar panel to boost power onboard. Solar panels are especially useful when boats are "off the grid" while cruising or on a mooring and unable to plug into a land line at the dock. Panels come in many shapes and sizes, some flexible and some rigid, and they can be placed virtually anywhere on deck or mounted to existing framework.

When one of my best customers wanted to add a few panels to his boat, I naturally said, "Why not?" Although I have added panels to many sailboats, his was a power boat that presented some special challenges. When we first met about the project, he showed up at my shop with a folder of research, photos, and ideas — as usual, he had done his homework!

His boat is a Formula Thunderbird, a 36-foot Performance Cruiser, with existing canvas that consisted of a bimini enclosure going back under a fixed factory fiberglass arch. I had created a new enclosure for him last season, so I was very familiar with his canvas design and framework. The panels he had purchased, Sunforce/85 Watt Crystalline Solar Panels, had to fit on top of his existing bimini framework and be strong enough to handle the load under speeds up to 22 mph with a 25 mph headwind, totaling 47 mph over the panels! Usually on a sailboat, the panels can be just offset with a Gemini mount to sit directly on top the bimini frame. However, this customer’s frames were bigger than the solar panels and, of course, none of the spans matched up. This meant that I would have to create a separate structure to attach the panels to, so they would sit above the current bimini. This separate structure would then have to attach to the bimini — but how???

The best solution we came up with was to add handrails to the sides of the bimini and to attach the separate structure to those handrails. The customer was all for this, given that he needed some handrails on the sides anyway. He has only a six-inch walkway going forward to the deck, and his current lifeline rails didn’t go back all the way to the arch. The new handrails not only worked for the structure, they added safety and security for those going to and from the deck.

The handrail addition was easily executed by adding Gemini standoff side mounts. The forward mount worked perfectly with the join in the canvas of the top front windscreen and side panels. The aft mount, however, did not, and I had to cut an opening in the panel to allow the mount post to come through to the outside. I then cut rails using 1-inch tubing to match on each side. T-brackets for the upper solar structure were placed forward and aft on each rail before riveting on the rail eye ends and attaching them to the boat. (I always rivet my handrail ends for extra support and safety.)

Once the handrails were attached, I could determine the measurements for the upper structure. Because the structure had to sit above the bimini canvas, I needed to measure the height from the handrail to above where I wanted my structure to stand. I also had to get a width measurement forward and aft at the exact length of the solar panel, which was 47 inches. There was some room for error, but the panels needed to attach to those bars at the location of each hole on the bottom of the panel, and they needed to be placed in the proper location for the bow to take the weight of 25 pounds each.

After marking the handrails for port and starboard, forward and aft, I took them off the boat so I would have them in my shop when I bent the structure. This enabled me to do a dry fit of the panels on the table before installing them on the boat. I have found from experience that it is much easier to work out problems in my shop, getting all the fittings in place and installing the panels there, rather than when hanging 8 feet up in the air on a moving boat. It makes for fewer headaches and lets me know what to expect when doing the final installation.

I bent two one-inch stainless steel bows flat (with no crown) for the structure to hold the panels. I then attached eight Gemini split rail standoff side mounts onto these bows and laid everything out on the table. One thing I found out early was that there was not enough clearance under the panel to fit a screwdriver when attaching the panel to the mount! So, the screws on the mounts were changed out to hex head cap machine screws to allow a socket wrench underneath for tightening. It took about two hours to bend the bows and dry fit the mounts and panels on the table. At last, I was ready to meet my customer.

At the boat, we first put on the handrails and then the two bent bows. After stepping back and looking at it all, we decided to cut down the bows a bit. It took two cuttings to create a profile that we liked, and then we were ready to install the panels. Before putting them on, however, we discussed where the wires should run. This is very important as it affects which ends will face forward and aft. Usually, the wires need to run with the least possible length to the battery area. In this case, my customer wanted to run everything to the fixed fiberglass arch, so we placed the panels with the wire box to the aft. It was kind of windy that day, but we were able to get the first panel in place and loosely fitted before doing the second panel. Once both were in place, we made some adjustments with the set screws on the T-mounts to make sure that the forward-to-aft placement on the boat worked well. Finally, we tightened everything down nice and snug. Because we took the time to make the design visually pleasing, it looked like the panels were part of the existing canvas structure.

Since adding the solar panels, my customer can run everything on his boat without having to top off his batteries. On a sunny day, the two panels produce 170 watts of peak output, and they produce half of that on a cloudy day. To ensure that he did not "cook" his batteries, my customer also installed a 12-volt digital charge controller. He can now run his fridge continuously on the mooring and not have to empty it after every weekend cruise. He can even keep ice cream frozen!

Going solar provides clean and free energy, without having to turn on a generator that runs on gas, polluting the air and costing money every time it is used!

To find out more about adding solar panels to boats and the Gemini standoff side mount fittings, visit www.GeminiProducts.net.