DIY Simple Solar Installation
Harnessing the sun’s rays and converting it to electric energy almost seems like a miracle and certainly not always straight forward. On a sailboat, mounting options for solar panels can be limited and often costly. Information in regards to connecting solar panels to the existing charging systems can be confusing or even misleading. A simple solar installation doesn’t have to be complicated, or even difficult though. In this example we’ve designed a straight forward setup of two solar panels, a low cost charge controller, 12 volt, Ray Marine Tiller Pilot, and USB outlets with appropriate fuses. In this project we’ll not only connect everything and cover the basics, but also reveal the simplest way to install the physical solar panels themselves.
The Diagram
From a diagram perspective adding solar to your existing electrical system can be as simple as connecting a panel to a charge controller and the charge controller to the existing battery, completely ignoring the rest of the system connected to that same battery. Four wires. Plus and minus from panel to controller. Plus and minus from controller to battery. That’s it! Installed Done. Get back to sailing!
In many cases it really is this simple. As an added bonus, most charge controllers can provide real time and accumulated charge statistics. The only two parameters that need satisfying are:
- The charge controller must be compatible with your battery type. (Lithium, Lead Acid, AGM, etc.)
- The charge controller input capacity must match the maximum output capacity of the panel.
Theoretically, no fuse or breaker should be required as the charge controller has the ability to protect the battery. There would however not be any harm and very little cost to follow best practices and add an inline fuse or breaker between the panel and the charge controller.
To take full advantage of the charge controller’s features, the “load” (Everything connected to the battery that consumes power.), should also be connected to the charge controller. This would then provide real time or accumulated consumption statistics. However, it also means you have to match the LOAD capacity of the charge controller to the maximum load expected from all simultaneous power consumers. Often this will lead to a higher cost of the charge controller.
There are two ways to connect multiple panels. Parallel or Serial. There are drawbacks and advantages of either. If shade were not an element that needed considering, a serial connection provides the highest combined output. However in a serial scenario, if one panel is shaded the output from ALL the panels suffers. On a sailboat it’s almost certain some panels will be shaded some of the time. Thus connecting in parallel is by far the more common choice.
here is our final diagram with the solar panels connected in parallel.
Final Notes
Make sure to purchase a few solar specific connectors. They crimp on easily and are weather proof. Your solar panel will likely have these already.
Ensure there is space for air to circulate under the panel as they do get very hot when they produce to full capacity.
The main drawback to installing solar panels with Sikaflex is that if you wish to remove them, it is a LOT of work to remove all the Sikaflex residue.
The Install
A while back I installed a backup auto tiller, necessitating access to 12V at the stern. I had already started thinking of a separate battery, small outlet / breaker panel and solar charging. In addition to powering the Auto Tiller, it would also supply power to a portable freezer without it draining the house batteries on long passages. I decided on a 100 AH LiFePO4 battery.
I also procured the cheapest charge controller compatible with LiFePO4 and with the capacity required. Two 50 Watt solar panels were already in my possession.
Before committing to an actual installation, I wanted to make sure everything worked by setting up a simple testbed.
The above setup is exactly like the final diagram to the left, except I have yet to procure and install the breaker and the light is the actual freezer.
Cutting boards make great project materials on boats. here is the panel with charge controller, Raymarine Outlet and a 12V lighter socket. (The light in the diagram)
The solar panels are simply adhered to the coach top with Sikaflex. I wiped it down with acetone before applying Sikaflex to the bottom of the panel, followed by placing the panel on the coach top. A portable camping stove rested on top of the panel for the first 5 hours to apply some degree of pressure.
