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Old 26-01-2011, 22:03   #1
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Solar Panels - Bimini or Davits - Pros and Cons of Both

Well I finally got myself 2X85w solar panels and a wind generator. My question is regarding the solar panels. I am torn between installing them on the bimini or on the davits. For people who have panels mounted on these 2 spots what do like or don't like about it? Are you getting enough power due to their location? Do you really need to angle them?
Thanks for any input
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Old 26-01-2011, 23:09   #2
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we used on bimini and i plan on doing same. worked just great as it was. only hting different --mine is a ketch and i cant p0lace my ind genny on my quarter, as we could with the sloop.... and up the mizzen is my radar.......so i go to drawing board
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Old 26-01-2011, 23:33   #3
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Originally Posted by endeavor View Post
Well I finally got myself 2X85w solar panels and a wind generator. My question is regarding the solar panels. I am torn between installing them on the bimini or on the davits. For people who have panels mounted on these 2 spots what do like or don't like about it? Are you getting enough power due to their location? Do you really need to angle them?
Thanks for any input
Great question,

I am also undecided... hope for some feedback of whether the priorities should be shading or weight at the ends?
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Old 27-01-2011, 00:13   #4
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Depends on the height of the davits. If it will restrict the lowering or lifting of the dinghy etc. If davits at shoulder/eye-level could often bump head whilst using davits.re dinghy.Might have to duck under them to get into dinghy at stern of boat. If height is an issue then bimini is way to go. Otherwise how will shade from mainsail affect panels ontop of bimini. If this not an issue again bimimi would be my choice.
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Old 27-01-2011, 03:41   #5
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We have two panels on top of the bimini and it's worked great. Haven't had a need to angle them. At anchor we move the boom to minimize shade. With the panels covering up the bimini, it's also extending the life of the canvas.

The real negative is the bimini is now up permanently. If we got caught in a big blow, there's no way to take it down quickly.
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Old 27-01-2011, 05:18   #6
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Those with solar panels on their bimini, did you reinforce your existing bimini and how (starboard panel mounts and/or rails to the stern pulpit), or did you opt for a different beefier bimini, and by beefier do you mean wall thickness or stance or both? Has anyone simply extended their bimini horizontally to accomodate additional solar panels?
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Old 27-01-2011, 05:34   #7
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Quote:
Originally Posted by dennisjay View Post
The real negative is the bimini is now up permanently. If we got caught in a big blow, there's no way to take it down quickly.
Exactly... this was my 4purpose solution for Panels, Generator, Dinghy and chin up/exercise bar.....
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Old 27-01-2011, 05:37   #8
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I added one horizontal section and one vertical on each side.
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Old 27-01-2011, 06:05   #9
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We had two 75 watt panels on thte bimini for years. It worked alright, but it did somewhat compromise the bimini, in that it was difficult to tension the canvas properly, or to remove the bimini for storms. It was also hard to keep the bimini clean under the panels. All of those problems could be fixed by redesign, but when we made the current bimini, we removed the panels.

We built a structure of stainless tubing, using stock fittings and 1 inch tubing, to hold the panels about 18 inches above the davits, which we already had. That has worked out better for us than the bimini mount, but it's mostly a matter of personal choice. We have had fewer problems with shade from the sails or the boom since we moved the panels to the davits. We've never bothered with tilting them, although we did build that possibility into the davit mounts. The practical gain is pretty small if you are swinging at anchor.
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Old 27-01-2011, 06:09   #10
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To mount the solar panels we attached fore and aft tubes on top, from the middle to the aft bimini bow. These stiffened the bimini considerably. We cut the bimini cloth to zip around the tubes. We kept the solar array narrower than the bimini itself for aesthetic reasons. The other posts describe the pros and cons. Shading is not an issue for us. Picture in my gallery (sorry, couldn't paste it).
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Old 27-01-2011, 06:59   #11
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Mine are installed above my davits and if you are able to do the same, IMO it is the best option:

1. you will definitely get less shading - especially with the mainsail up, but also under anchor.
2. it tends to be a sturdier mounting location than a soft bimini.
3. it does not interfere with the function of the bimini, or the ability to take it down in storm conditions.
4. it permits easier adjustment, at least for and aft.
5. the solar panels also provide something of a 'roof' for the inflatable, reducing the amount of rain water that can get into the inflatable and also the exposure of the fabric to UV rays.

Brad
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Old 27-01-2011, 07:25   #12
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Thanks for starting this discussion. I don't have nor intend to get davits. But I have had a pair of very effective solar panels which have sat on the coach roof in front of the dodger with the sail control lines running under them. It's worked fine, but requires lashing then in very heavy weather or removing them which is quite easy and stowing them below.

The idea to get them off the deck appeals to me for multiple reasons and I am getting a bimini and in the process of designing it so including a perch for the panels is definitely in the mix.

I think that ... based on some comments below.... I will use an "add on" structure which is attached to the king and queen bows (the two main ones of the three). This will be a simple tube clamp with a bracket for a "hinge"... the same fitting on the base of the king bow, but set up at the top below the edge of the canvas.

These four fittings will enable me to create a pipe perch which rides above the bimini for the solar panels. It can be easily removed... though getting at the panels may be a bit tricky once they are up there.

It wouldn't be expensive and it would be a DIY project which could be scraped if it didn't work out without trashing the bimini at all.

What say you?
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Old 27-01-2011, 08:24   #13
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I put my 280W of solar panels in 4 locations, so that when one is shaded the other three are not. By far, the 110W one on "faux davits" in the back, is the one that kicks ass! I can hinge it toward the sun, and get 2 more hours in the morning and evening. Between all 4,I get high 50 AH or even 60 on a good day, or around 30AH if really overcast.

If using multiple panels, where one is usually shaded, it IS good to use a Shotky Diode in the + wire of each panel. There is a small loss of V from this, but IMO, not as much as the loss from the sunny panel, backfeeding into the shaded ones. (Shotky diodes are the type create the least power loss) Some argue against their use, but I have had solar on my boats since the 70s, and feel that their use is warranted with my 4 separate panels. (with or without works fine, however)

The best location for a wind unit is on a mizzen mast! If you don't have one, a stern pole is all that is left. This is unfortunately the best place for one or two HUGE solar panels that can tilt, and in the typical living anchored lifestyle, with occasionally being at sea, the solar will produce most of its power, or > 1/2 of it, 90% of the time, where as the wind unit will produce 5X what you can use 10 or 20% of the time, and near "0" the rest of the time. At sea is where they earn their keep!

That being the case, if you have no option than put the wind unit on a stern pole, you might as well put the solar panels on a bimini rack, and accept that one will be shaded at sea, but not necessarily the majority of time at anchor.

Solar does not like dark shadows, like from a near by wind generator 7' away. A really dark shadow over just 15% of a panel might knock it down to only 10% of its rating. If there are no DARK shadows however, a very cloudy, NO sun, but bright white sky, will still produce about 75% of its rating!

So... having one on the bimini totally shaded by the mainsail under way, but the other not, is probably better than two on the back with a relatively small, but dark wind generator shadow across both of them.

Many books on the subject have done a disservice by showing a radar arch, or stout davits, with BOTH solar and wind on them! It that location, it is better to have one or the other.

My cruising has been about 95% living anchored out and working on the boat or diving, in a beautiful tropical location, and the other 5% spent at sea getting there. I used to have a wind generator also... (for many years). When I swapped it out for my aft 110W solar panel, we had so much excess that I downsized the house batteries! Solar was so much more reliable in my type of cruising...
Don't forget to fuse the panels!

Best of luck, Mark
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Old 27-01-2011, 08:41   #14
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This is great thanks for all your input. I think I am leaning towards doing the davits. My concern on the bimini is storm conditions first and second I sometimes enjoy folding that bimini back and letting the cockpit fill with sunshine. Its a nice open air feeling.

I never thought of the panels on the davits protecting the dinghy from sun and rain water. Good point.

I've also given a passing thought to that Solar stick, so I can mount panels and windgen on one unit and rotate and fold panels. Its expensive though.
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Old 27-01-2011, 08:59   #15
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I've also given a passing thought to that Solar stick, so I can mount panels and windgen on one unit and rotate and fold panels. Its expensive though.
I looked at the Solar Stik prior to building my solar bimini, but found that having a custom frame fabricated and installed by a local yard actually cost less than the Solar Stik would have.
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