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Old 19-03-2013, 12:57   #1
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Tilting solar panels

Hi everyone,
This might seem simple to some but clearly not to me. I have two x 135amp Kyocera solar panels, hard mounted to a purpose built stainless steel tubing rack on my full width bimini. The problem was I only read about tilting them after they were installed.
Silly me.
Now I have a couple of questions.
I am a blue water sailor & will be heading up to 40 degrees N shortly.
How do I & what do I use to, both safely effectively tilt these panels of mine to take advantage of the available sun. I'm thinking they have to be omni-directional. More complications. Lastly, why doesn't it matter what season it is given the sun's trajectory across the sky.
Any & all info would be a great help.
Many thanks cruisers.
Trish
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Old 19-03-2013, 13:33   #2
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Re: Tilting solar panels

If you are going to be anchored out, tilting the panels would be a full time operation to track the sun. You would need a universal joint gimble mount to be able to track the sun as the boat and the sun moved around. You will lose some output as you climb to higher latitudes and sun angle increases. Not much you can do about it unless you can fix the orientation of the boat which would require fore and aft anchoring. That in itself is a major hassle if you are regularly moving locations. Also, you'd be less than popular if you are the only boat in a crowded anchorage that isn't hanging off of a single hook.

If you are going to be sailing/powering on fairly fixed headings for hours a gimbaled mount would help. A bigger problem is the probable predominance of overcast as you go north. On the West Coast, sun is a rare occurrence on the inland passage. Any overcast seriously cuts photovoltaic output. If the sun is completely obscured, output is cut by 90% or so. You've got a double whammy there as also there is little wind so a wind generator won't work either.

I'd wouldn't concern myself with gimballing your panels unless you can do it easily and cheaply. Giving them a clear shot at the sun without shading would be your most productive option. Take whatever charging you get from the panels as a blessing and enjoy your cruise. Optimize your engine charging capacity or, heaven forbid, add a generator if you have high electrical usage. Find ways to reduce your electrical useage.
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Old 19-03-2013, 13:49   #3
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Re: Tilting solar panels

It would help if you can tilt your panels at least seasonally, more horizontal during the summer, and increase your angle going into fall winter.
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Old 19-03-2013, 13:55   #4
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Re: Tilting solar panels

I agree with Roverhi finding as shade free location is the first priority. However tilting the solar panels can achieve significant gains.
My panels can be tilted in one axis over close to 90 degrees. In summer when there is plenty of solar power I generally don't bother, in winter when the sun is lower and production is less I adjust them several times a day.
If you have room and can install more panels this is preferable, given the cheap cost of solar, but there is some satisfaction in seeing the ammeter climb with an angle adjustment.
The biggest advantage is when the sun and production is low, the gain is biggest.
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Old 19-03-2013, 16:14   #5
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Re: Tilting solar panels

Keep them flat, and if you are going further north for the summer rely on the longer days to give you more juice, well 40N isn’t very far north but the days of summer will be much longer than 10-20N
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Old 19-03-2013, 17:50   #6
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Re: Tilting solar panels

Do tilt them if you can. Huge gains.

You can build/buy a single leg pivoting supports that will tilt in any direction. Google some, they are out there.

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Old 19-03-2013, 18:19   #7
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Re: Tilting solar panels

There are two pieces to this puzzle, and both are difficult on a boat at anchor. The first is azimuth, you want to keep the panels pointed toward the sun, the second is altitude, you want them tilted up so that the panel face is normal (perpendicular) to the sun.

In a fixed tilt land installation we would generally point the panels south (azimuth - talking northern hemisphere here, apologies to our friends down under) as a general compromise since that is the direction when the sun is at its brightest. Then tilt them, again in a general compromise, for peak production during the summer.

The biggest reason that panels are installed flat on most boats is that you have a problem controlling the azimuth. If you tilt them at a nice angle, and then the boat swings and shows the back of the panels to the sun then you are losing big time. If you leave them flat then you're at the general compromise position when you can't control azimuth.

Production from flat panels at midsummer noon at 40N will be 97% of maximum possible (sine 77), in midwinter your maximum production will be 39% (sine 23) of maximum available. Those are mid-day values with the panels flat, production values relative to maximum will drop as the sun does. If you're up to continually working to keep your panels pointed in the right direction you can see that there can be significant gains, particularly as it gets later in the year and as the sun gets lower in the sky and the panels get farther from normal to the sun. The amount of power that your panels can generate is the sine of the angle between the face of the panel and the sun (or cosine, depending on where you measure from).
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Old 19-03-2013, 19:16   #8
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Re: Tilting solar panels

Boat accessories, easy to assemble | NOA Aluminium AB NOA Aluminium

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Old 19-03-2013, 19:33   #9
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Re: Tilting solar panels

Well, if you've got deep pockets, checkout www.solarstik.com their marine product is a heavily engineered "mast" with two "wings" that swing and tilt, so the solar panels can always be oriented toward the sun. It is pricey, but I doubt you could have a similar mount of a similar strength fabbed up for less. They can be mounted outboard on the transom, or inboard in the corners of the cockpit.

Short of that, you just have to look at your options, how much you can fab up or are willing to pay to have fabbed up, and how much power you will lose. IIRC you lose about 10% of the available solar power for every 15 degrees (one hour of solar movement) that your panels are not pointed directly at the sun, even if they are angled properly for the latitude.

I've seen solar panels on street lights that are mounted on a sort of curved bow-shaped tube, with a compression fitting that allows them to rotate and as they slide across the arc of the bow, they also tilt.

More important may be the compromise to keep the panels where they are protected and also unshaded. Any shade on a panel, at all, will degrade the output from the whole panel.

If you are not going to be there to shift them every hour or so, then keeping them flat is of course the best compromise.
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Old 19-03-2013, 19:34   #10
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Re: Tilting solar panels

the people who sold me my panel (kyocera 135) also made up some mounting hardware for me so i could tilt it in one axis. works well although of course i have to tilt it manually. he also demonstrated to me how big a difference it makes when the panel is flat to the sun. aimed at the sun it puts out 7.5 amps; flat it put out 4.

two flat aluminum bars are attached to the underside of the panel, each with a pillow block. these are clamped over a stainless tube that runs lengthwise with the panel. the panel is thus able to rotate around the tube.

a light line is attached to each corner of the flat bars. these are tied to the stanchions and used to control the angle of the panel. that's the manual part of the tilting job.
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Old 19-03-2013, 20:21   #11
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Re: Tilting solar panels

This may give you some ideas.

Solar Panels and Associated Systems
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Old 20-03-2013, 01:24   #12
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I used Atom Voyages design, showed a local metal fabricator and he made them up for us. I swear by this design, we never ran out of power.

http://atomvoyages.com/gallery/video...nstration.html
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Old 20-03-2013, 02:03   #13
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Re: Tilting solar panels

Quote:
Originally Posted by surfingminniwinni View Post
I used Atom Voyages design, showed a local metal fabricator and he made them up for us. I swear by this design, we never ran out of power.

Atom Voyages - Atom Solar Tracker Demonstration
Great design, but would it work on a big pannel over 200 watts?
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Old 20-03-2013, 03:10   #14
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Re: Tilting solar panels

Quote:
Originally Posted by Ram View Post
Great design, but would it work on a big pannel over 200 watts?
I agree. tilting panels is fin in theory, especially if your panels are small, or singular. I have 3 x 185watt If I think about tilting I will

1. Significantly weaken the fitting (or increase the weight of the gantry).

2. Risk shading the panels from the one up-sun.
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Old 20-03-2013, 03:21   #15
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Quote:
Originally Posted by Ram View Post

Great design, but would it work on a big pannel over 200 watts?
I had 2 x 85 watts panels. 1 on each. Withstood winds of over 50 knots at anchor, with no issues.
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