The Dollars & Sense of Solar Panels (Blue Water Sailing, February 2005)

By Carolyn Shearlock © 2011 • all rights reserved

Does a large array of solar panels make sense for your boat?  Here's how we decided -- and the answer was a resounding YES!

NOTE: This article refers to our previous boat. Adding significant solar was also the first major upgrade we did on our current boat — read about that here.

Our first major boat improvement was to significantly increase the solar power aboard Que Tal, going from 153 watts to 453.  As a result, we virtually never ran the diesel (or a generator) just to charge the batteries — even with a decent-sized refrigerator in the tropics and a watermaker.  We knew that the solar power would heat up the boat less, but an unexpected bonus was that the refrigerator ran less — the engine compartment was right next to the refrigerator, and not running it sure helped!

As our first big project, we struggled with numerous questions about whether it was worthwhile to do and how it would improve our cruising. I documented our analysis in “Dollars and Sense of Solar Panels,” published in Blue Water Sailing in February 2005. And yes, whether considered on a straight dollars and cents basis or in time saved (and spent on other, more fun, things), adding a bunch of solar panels was one of the best upgrades we made to Que Tal.

Admittedly, solar panels aren’t the right solution for every boat — you have to be cruising where it’s sunny.  But the same framework for determining whether they’d be cost-effective for us, detailed here, can be used for other charging options, such as a wind generator or a gas or diesel generator.

The original article included a large sidebar on places to mount solar panels, with lots of photos. I have placed this in a separate PDF, available here as Dollars & Sense of Solar Panels (Supplemental Info) as putting it all in one made browsers with slow connections crash.

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Comments

  1. The one question that I have , that i did not see information about in the article , was , how many batteries are they running , and are they 6 volt or 12 volt ?

    thank you

    • Carolyn Shearlock says:

      Thanks for asking, Victor —

      We had 450 amp-hours at 12 volts. We actually had 4 Trojan golf cart 6 volt batteries, 225 amp hours each and hooked them together in parallel and series to form the 450 amp-hours at 12 volts. No change in the battery bank in the process of adding to the solar panels.

      Carolyn

  2. Al Felker says:

    1. When on shore power, do you turn off shore power battery charger?

    2. When running engine, do you turn off solar charger?

    I only ask because the solar charger will stop charging once it sees something else charging the batteries.

    • 1. If the shore power was metered, we’d only use it when we needed to (sometimes we were doing power-intensive projects that used way more power than the solar had).
      2. We never bothered to turn off the solar charger as we didn’t see any harm in leaving it on and then we didn’t have to remember to turn it back on when we shut down the engine.

  3. Do you turn off the solar charger when using shore, engine or genset?

  4. What is the best brand of solar?

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