Flexable Solar mounted on mast

[zboss]

Originally Posted by John Holbrook

How long before the design of a boat is dictated by how many solar panels and wind generators can be mounted on it? Getting rid of that pesky mast and rigging would help😄



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There are a few of these on the ICW. Cats that have had their masts and rigging removed, every inch of the cabin top covered in solar panels and the engines replaces with electric.

We have a friend that switched their catamaran over to electric (kept the sails) and he can make 2.5 knots indefinitely as long as the sun is shining. They produce enough power to recharge the boat so it will still run at night at the same 2.5 knots.


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[Stumble]

Originally Posted by DITB

Solar on the mast, just saw it mentioned somewhere else then I found this thread by coincidence.

When considering the angle of incidence of the sun, it is normally for static installations (land based), with surrounding terrain of various sorts and variations. At sea, besides being on a moving platform, one should consider that - especially high up in the mast of a sail boat - there is a lot of reflection coming from the sea. This obviously depends on waves, visibility, cloud cover and such. If you think it doesn't work, think how fast you tan at sea:



In other words:

Morning and evening, you get an optimum angle for that initial boost to get things going and a top-up in the evening before sunset. But all day, a huge mirror around you provides plenty of reflected light.

In theory.

I don't know how significant it is, especially not for those frequencies of light that are reflected.

If someone out at sea has a loose solar panel they can move about, the sun high enough in the sky, try and move it in different directions to see how the yield varies.

It really comes down to $/watt. At the extremes, if the panels are free then you could cover the entire hull wi panels, and the area would generate lots of power, even with low efficiency. Since they are also in a place that won't interfere with anything else, and the weight is low, it's an all around win.

But if the price has to be taken into account... well it probably doesn't work out so well. My guess, and it's just that, is that panels mounted in the hull or the side of the mast will generate less than ten percent of their rated output.

[jamhass]

As has been noted, the angle to the sun is extremely important. The relation is the Cosine of the angle between the normal of the solar panel (i.e. where the panel is "looking") and the sun. Thus when the panel is pointing directly toward the sun (angle is 0) Cos is 1 and power is maximum. At 90 degrees, Cos is 0, so no power at all.

A panel mounted (say "wrapped around") on the mast will point towards the sun only near dawn and dusk, and generally away from the sun at all other times.

Thus, you can't expect such an installation to produce much usable power.

[Salty Mike]

If a mast were covered in thin film solar panel it would be mighty pretty. If those panels were covered in a layer of micro prisms that changed the angle of declination to the sun it might make some usable power.

[valhalla360]

Placing them on sails is just silly unless you are doing something like a round the world race where money is no object. Are you really going to put up your sails at anchor so you can get some solar power? Even just heading to upwind in a channel, you will lose more power from wind resistance than the solar could possibly produce.


For house loads, an arch with a few hundred watts of panels is typically plenty. No need to mess around with exotic installations.

In reality, we are starting to see solar becoming a serious design consideration. Cats are built with large arches and cockpit overhangs which provide a place to mount large solar arrays. I suspect, we are seeing the tail end of the change (in new designs) as even with huge arrays, getting enough space to support propulsion is not reasonable both from a physics and an economic point of view. Now if someone comes out with a battery that is reasonable cost and holds 1/4 the energy of a gallon of diesel, it likely will be the end of the sailboat as the most common cruising boat. If you could start a trip with 400-500miles worth of range 80% of hull speed and supplement that with 30-40miles of range per day (assuming most of the boat covered in panels). Most coastal cruisers would likely switch over and coastal cruisers buy the majority of new boats. Assuming you could drop back to 4-5kts and bump the range to 800-1000miles and gain 60-80miles per day from the solar (lower speed is typically more efficient), you are likely to see even long distance cruisers start to make the switch.


Yes, there will still be sailboats but honestly, I would say 80-90% choose sail not because of a love of sailing but because it's more cost effective (even if you never raise the sails).

Of course the big issue is batteries provide nothing close to these ranges and solar arrays large enough for even modest daily power generation conflict with using sail.

[Salty Mike]

Boy, I hope it's not the end of sailboat cruising I'm just stepping into the lifestyle almost got the boat ready we hope to leave out in the next few months please don't let it stop now...

[valhalla360]

Originally Posted by Salty Mike

Boy, I hope it's not the end of sailboat cruising I'm just stepping into the lifestyle almost got the boat ready we hope to leave out in the next few months please don't let it stop now...

No worries. The technology is no where close.