Solar Panels

Over the past year we have experienced a noticeable increase in inquiries regarding solar panels. At the 2014 Vancouver International Boat Show, we had a couple of solar panels on display in our booth and they were a constant topic of conversation. It may surprise you to know that the reason many boaters are turning to solar is not to save on operating costs but to add to their quiet time at anchor and to be kinder to the environment. As an added bonus, the technology is getting better and the cost is coming down.

Options  The two main types of solar panels are crystalline (rigid) and thin film (rigid or flexible). Thin film are roughly half as efficient but are far more reactive under low light situations like a typical West Coast overcast day. Crystalline panels last a lot longer and are usually guaranteed for about 20 years whereas the typical thin film panels are less than half of that. The great thing about the thin film panels is that they are lightweight, flexible and can attach to your existing bimini with Velcro, snaps, or zippers without changing the aesthetics of your boat. You no longer need a giant, silver domino hanging on your boat railing.

Thin film panels, such as the Solbian Solar Light Series, use mono-crystalline silicon cells and are incredibly light. The 80-watt panel weighs 1.3 kg and is only two mm thick. They can be installed with up to 25 percent curvature on a bimini or awning, but can be installed on a rigid surface and you can also walk on them. This allows them to be permanently installed for the boating season.

There are a number of mobile options such as the foldable or rigid crystalline SunForce, the flexible, rolled PowerFilm panel or the Ganz Marine weatherproof panel. Another option is the Dura Lite Blue Fibreglass solar module: these panels are slim, lightweight and claim to have double the output of conventional thin film panes. Made from a laminate of fibreglass and sunlight-resistant polyester film, they claim to be almost unbreakable. These panels are designed to be put out in the sun to charge a battery and then stored away. They are available up to 20-watts and are a good solution for maintaining you starter battery.

Daily Output  One of the most common questions we get about solar panels is how much daily output should one expect from solar panels in southern B.C. cruising grounds? Without getting too involved in the nitty gritty of a long calculation, there is a shortcut to convert watts, the unit of measure used to quantify the output of a solar panel, and the realistic output in daily amp-hours (Ah). Simply, take any solar wattage and divide it by either four if you are optimistic on the output, or divide wattage by five if you are conservative. For instance, a 100-watt solar panel should provide optimistically 25 Ah/day or conservatively 20 Ah/day.

Now that we can easily quantify the daily Ah output from a solar panel, how many watts of solar panels should a boater get for their vessel? Aside from the obvious factor of cost, there are other points to consider: your daily power budget and the amount of physical space where the panels can be mounted.

An Example  Let’s take my own Catalina 36 as an example. During the summer months I have a daily Ah budget of about 100 Ah per day, which is typical for mid-size power or sail vessel. Since my boat does not have a genset I want the solar array to potentially generate all the daily power.

By wanting to maximize daily solar output, I decided to cover all the available space on both the bimini and the dodger. Luckily, flexible solar panels come in many different sizes and this allows one to maximize the area to be covered. In the end, I was able to accommodate six solar panels on my existing canvas. There are two square 50-watt solar panels on the dodger, each on either side of the boom. The bimini has a total of four panels, three rectangular 100-watt panels side-by-side and one rectangular 50-watt panel just behind the backstays. All in all, this totals 450 watts of solar panels.

There was no need to create a mounting structure to accommodate those panels, my canvas maker, La Fabrica was able to affix them directly on top of the existing canvas. With 450 watts of solar panels my daily Ah output varies between 100 Ah to 125 Ah.

Other Considerations  Not all boaters will want to match their daily power consumption with a solar array. Many boaters choose to have a solar array that will extend their time at anchor without using conventional charging. For instance, a solar array for your boat could extend your time at anchorage from two days to three days.

A common concern on the West Coast is the lack of sunlight during the day. This is true during our rainy, winter season but often boaters who install solar panels boat from May through October when there is more than enough sunshine. Another concern is the high cost of solar panels. If your decision is based purely on generator run time and dollars per hour, then solar is not for you.

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At the end of the day, Solar provides a lot of green benefits. There is no additional exhaust or petroleum byproducts released into the air and water. It allows you to stay at anchor longer without the noise, vibrations, and fumes of your generator. To top it off, if you are sitting in the sun relaxing wouldn’t it be nice to know that your solar is hard at work?

About the author: Jeff Cote is a systems design engineer and owner of Pacific Yacht Systems, a full service shop delivering marine electrical and navigation solutions for recreational boats. Visit their website and blog for info and articles on marine electrical systems, projects and more:

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