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Solar Power Planning

By Paul Shard, Copyright 2015. All rights reserved.
Ever since we sailed down from Northern Europe to the sunny south of France and across to the Caribbean I have been hoping to be able to soak up some of this beautiful sun with solar panels. In our northern cruising with Distant Shores II I do not think they would have added that much, but here in the south is the place!! But I do not want to just start dangling solar panels on the boat without thinking it all through. We are proud of the sleek look of Distant Shores II and want to keep that as much as we can.

First I tried to plan an installation with flexible panels that were attached down on deck. Appealing since the lines of the boat would not change. I have seen another Southerly that has this and it was very tidy. There were 2 problems. With the available deck space, the amount of solar power added would not be nearly enough to satisfy our needs! It would be great to have a little to top up power when hauled out in the boatyard but it wouldn’t make much difference to our power budget afloat. Secondly the position on deck would mean the panels were often shaded by mast, rigging etc, so power produced would be even less. Unless you have a catamaran with large open deck spaces, solar panels mounted on deck will produce much less than you might hope for.

So I went to work planning an arch that I thought would complement the sleek looks of the Southerly 49. I am planning it in aluminum for lightest weight. Here is my first draft at a solar arch on the stern. Drawn to scale the sailor is 6’2 to walk under it.

What power do we need?

If you are going to plan solar power for your boat, knowing what you use is a definite starting point!
No denying that aboard Distant Shores II we are a power hungry boat! We have all super efficient LED lighting, excellent Frigoboat fridge freezers, efficient Caframo fans and more modern efficient equipment. Our 2 MacBook Pro computers are often on as we are aboard rough-editing the next episodes of Distant Shores Sailing Adventure TV show. It all adds up. Now that we are in the tropics both our fridge/freezer and our top loading freezer are using more power here in the warm climes. Our budget for power has crept up to nearly 300ah/day at anchor - about the same as we use at sea! 300ah X 12V = 3600 watts.

This plan will allow me to install 3 panels each producing 155 watts for a total of 465 watts. West Marine estimates a solar panel might produce 5 times its rated in a day in the USA (hopefully we’ll get more in the topics?). To get our daily production estimate we can multiply 465 by 5 hours of full sun as a simplified formula = 2325. So we might be getting 65% of our daily use.

Do you know how much electrical power you use on your boat?

Check out this blog on calculating your power usage with an overview of the process…

Planning a trip to the tropics? Solar Power might be in your future… here is an episode of Distant Shores below… you can download the whole 24 minute episode to view on all your devices…
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