Installing solar on the boat was on our project list for some time now, along with 125 other items of which we are proud to say only a handful remain! Solar panels aren’t new, but have come a long way in terms of size, weight, and energy output. Installing solar on the boat gives us a certain level of freedom from having to run our engine as the only way to charge our batteries when we are away from the dock.
Let’s review, because for non-boaties this can be confusing. At the dock we plug a little yellow power cord from our boat into a power outlet on shore. This gives us all the AC (alternating current) power we need to power the following items on the boat, outlets, microwave, refrigeration and battery charger. Other items such as lights, navigational instruments, radio’s and even the simple act of running water which requires a pump, operates on DC (direct current). Everything running off of DC uses precious energy from our batteries in order to operate. Similar to how the lights and radio work on your car.
We use both AC and DC items at the dock, but when we find ourselves away from shore, we say goodbye to thought of using anything that is powered by AC and have no choice but to use items that are only powered by DC. At the dock our AC powered battery charger takes care of topping off the batteries. Away from shore, the only way to charge our batteries would be to start the engine. Starting the engine is not the end of the world, but what if there was a way to charge the batteries, allowing us to save money by conserving fuel and electricity? Oh wait, there is!
Now, let’s bring you up to speed.
Over the last few months we’ve been busy! We switched from using three Prevailer Gel batteries to using four Seavolt Group 31 AGM batteries (made by Deka / East Penn). The previous Gel batteries were exceptionally reliable but after 6 years they were weak and on their way out. We noticed our alternator on the engine would charge the batteries at too high of a voltage, thus overcharging them. We had no plans to upgrade our existing alternator, and we wanted batteries fully compatible with its 14+ charging voltage.
Changes we made:
- Upgraded our AC battery charger from the 20-year old original to a Professional Mariner ProNautic p30
- Installed a Victron Energy 600-S battery monitor.
- Ordered and built our solar setup, which included the following:
- Solbian 125W flexible solar panel – about 1/8th of an inch thick and only 5 lbs!
- Genasun GV-10 Maximum Power point tracking (MPPT) charge controller
- 10 awg wire that runs from the panel to a bus bar in the engine room, which in turn is beefed up to a 4 awg wire running to the batteries.
- The positive (+) wire has a 150amp ANL fuse installed near the batteries (AYBC standards say it should ideally be within 7 inches of the battery post, and we are somewhere near that distance)
All in all, it was a fairly easy installation. The trickiest part was snaking the wire from the engine room to the batteries mid-ship (often the case).
Our solar setup was informed by a well-respected marine guru who goes by the name “Mainesail”, and his site is a fantastic collection of detailed and knowledgeable articles on a wide variety of cruising topics:
We have been charging our house batteries exclusively off our solar panel and it works wonderfully! One of the great benefits of our ultra-thin and lightweight panel is that we can quickly take it down and stow it below in heavy weather to protect it. We would highly recommend them and may be adding a second soon!