Years ago when I spent as much time as possible sailing the waters of Long Island Sound on my 26 foot sloop, solar power meant a small panel or two that couldn’t do much more than generate the illusion of energy. Things are very different today with extremely efficient solar collectors and energy storage systems that reap the benefits of lithium-ion technology.
Sophisticated onboard solar equipment and systems can make sailors pretty much energy independent--but there’s a big caveat. These systems can be mighty complicated--way beyond wiring up a few simple panels. Few among us have the skills needed to design and install a proper system. Below is part 1 of an article written for Marine Electronics Journal by Julia Carleton, an electrical engineer and specialist in marine solar power installations.
Our goal in running the story is twofold: to dissuade anyone who thinks whipping up a sophisticated solar energy system on their boat is a do-it-yourself project; and to provide any boater considering solar power with essential topics to talk about with a qualified installer.
-Jim Fullilove, MEJ editor
By Julia Carleton
Twenty-five years ago, energy independence on a cruising boat was only for hearty souls requiring few comforts and willing to tarnish the aesthetics of their pride and joy with enough solar panels mounted that they could leave their sunscreen behind. With today’s technology it is not unrealistic to expect many of the comforts of home without having to run to the dock to plug in or fill up the diesel tank at every opportunity.
This is all possible while also enjoying quiet sunsets with no generator running and spending time in port exploring rather than troubleshooting. A reliable, efficient energy storage and charging system that caters to the unique characteristics of each cruiser is at the core of making these expectations a reality.
While manufacturers like Victron and Mastervolt can provide almost the entire lineup of products necessary to keep the nav lights on and the coffee maker brewing, there are some drawbacks to using a single manufacturer. The most significant one is that with such vast product lines, it is hard to stay on the cutting edge of everything, leaving space for smaller, more specialized companies to develop competitive and in some cases superior products. There is also a strong possibility that integrating a foreign component into the system will eventually be necessary and when that time comes, it might take some work to coax them into a cooperative relationship.
Better components all the time
Though the recreational marine market is small and therefore relatively slow to develop on the technical side, energy storage and charging products are steadily improving. Alternators are becoming more efficient and powerful. American Power Systems provides an alternator rated at 360 amps @ 12 volts that fits in the stock position. Reliable and safe lithium batteries are on the scene providing more Ah (amp hours) with far less weight and in a tighter space. Lithionics has managed to squeeze 555 Ah into a case roughly the size of two 12-packs of beer and weighing only 119 pounds.
Solar panels are reaching higher efficiencies with new products coming on the market regularly. Solbian Energy has teamed up with Merlin Solar to integrate Panasonic’s HIT cells, claiming 24% efficiency into semi-flexible panels less than 1/8 inch thick. With a properly sized and designed system a cruiser can enjoy more power-hungry amenities including microwaves, freezers, TV/entertainment systems, electric winches and windlass and even air conditioning and water heaters, all without the extra space, weight, and complications of a generator. All of these advancements mean higher currents, more heat, more complex programming requirements and higher stakes if something goes wrong.
The above factors have led to an emerging need for third-party energy system designers that have the time and resources for thorough system review, analysis and planning based on the unique characteristics of the boat and user. These designers should have knowledge of many different product lines and the ability to weave them all together into a robust and efficient system. Designers and installers are in agreement that this time investment on the front end pays off down the road during installation and testing. Projects of this complexity require seasoned installers willing to take on jobs that are far from run of the mill and could involve diving deeper than expected.
Design: more than meets the eye
The design process is simple in its approach yet complicated in its implementation. Size the energy storage system based on the boater’s daily loads with a 20%-40% buffer to increase battery life expectancy. Choose the type of charge sources based on how the user generally uses their boat then spec out those components based on the size and type of battery bank.
This seems fairly straightforward. The complication comes when all the components need to work together and be protected if there is a system fault. For example, if there is a high-voltage cutoff on a lithium battery, a scheme needs to be in place to turn off the alternator before the battery disconnects to avoid burning out the rectifier diodes. If there are batteries of different chemistries—thereby requiring different charge parameters—there needs to be a means to seamlessly keep all banks charged without wasting any precious power that is being generated. And the list goes on.
Enter the installer
Collaboration between the designer and installer is a key piece of the process. A system that looks good on paper might have some holes in it upon further inspection from an installer’s perspective. Steve Ecker, with Maine Yacht Center in Portland, ME, shared a story about installing a high-output alternator in an engine compartment that was just too small to adequately dissipate the heat generated by the alternator. Installation included both intake and exhaust blowers to remove the excess heat from the space but the alternator was eventually dialed back to keep the temperature down to an acceptable level.
From inception to commission, there must be a continuous dialogue relaying specifics on existing and proposed components, loads, dimensions and eventually the details on programming when the installation is coming to a close. Bruce Schwab of OceanPlanet Energy, a Bath, ME, company providing custom system design, reports that in a couple of cases this dialogue lacked critical details and some large loads went unreported, resulting in design changes after components had been delivered and installed.
Quality is key
Even if the system is expertly designed and perfectly paired with the user and space, the success of the system is still entirely dependent on the quality of the installation. Cable sizing and over-current protection are only the tip of the iceberg for installation concerns. Solar charge controllers have burned out due to installation without drip-loops. A seemingly innocuous tiny load installed between the battery management system (BMS) and the battery in a lithium system can result in a damaged battery. A single stainless steel washer installed between conducting surfaces on an alternator can result in excessive heat build up which can blow fuses or even start a fire. There are countless failure modes and the pressure is on for an installer.
While taking the time for a high-quality installation is important, it is also imperative to budget time for the shakedown. When asked for his advice to other installers regarding these systems, designer and installer Brian Johnson of BRJ Solutions in Seattle, WA, said, "Make sure to work some system grooming time into the customer’s mind. They need time to test in the area. It’s not like when the installation is done, they can just sail away.”
About the author
Julia Carleton is a partner and system designer at OceanPlanet Energy
, an integrated marine energy solutions company based in Bath, ME. She is an electrical engineer and holds a USCG Master 500 GRT Upon Oceans credential.
Next week: Lithium batteries and high-output alternators