Solar panels Location.

[gmakhs]

hello ,
MY boat has an aluminium roller bar that can hold the weight of the solars but i am not sure about how the wind will effect their stability , at this point i have the option of adding 100 watt or 200 watt of solar .
my mind telling me to add only one panel on the bar because this will give me the lowest wind vane but i do feel safer with 200 watt of solar , please check the photo and let me know your thoughts .
the yellow line is the base.

[djmarchand]

Well, I don't quite understand your diagrams and their captions. But mounting panels crosswise along the support will hold up much better to winds than a couple of panels mounted fore and aft.

It is tough to find space for lots of panels on a sailboat. More than 15 years ago I had one 135 watt panel mounted crosswise on the dinghy davits and three 35 watt flexible ones sewn to the bimini for a total of 240 watts. Today you can probably get two or maybe three 100 watt panels on a bimini.

David

[Suijin]

It depends largely on the strength of the bar and what kind of additional support you build.

My panels are mounted like your first illustration, on two 1” SS tubes, but they are wider apart and closer to the ends of the panels. They are mounted on a bimini that was in turn reinforced and braced with struts for and aft on each side.

If I were you I would look into building a frame that attaches securely to the aluminum bar, then mount the panels to the frame.

The aluminum extrusion frame of solar panels has a relatively thin and weak lower lip for fastening. It won’t stand up to strong twisting force. You’re best off fastening the panels down as close to the corners as you can, and fastening to the sides of the panel frame instead of the lower lip.

Can’t comment on the adequacy of one 100 w panel without an energy audit.

[gmakhs]

Thank you , I M considering adding an aluminium frame , to support both panels on the sides , the roller bar have hold my weight plus the 14 kilos that are on it on 30 knots of breeze and waves so it should hold the panels well.
the power use is autopilot and lighting , last time with 40 watts panel it took 3 days of hard autopilot work before I consider the batteries low .

[Pete7]

Auto pilot, lights, VHF, GPS and nav lights could add up to a bit if you were sailing at night.

Why not split the difference and have a 150w across the yacht which is what we have done. No one ever complained they don't have enough solar.

My installation is in post 107 of this thread and it is worth reading through the whole thread to see what everyone else has done and the lessons learnt.

http://www.cruisersforum.com/forums/...-179638-8.html

Pete

[gmakhs]

Pete, I am.sorryfor the mistske thisn is what I ment GPS , VHF , navy lights , lights , and auto pilot .

My problem is that I can't spread solar around the boat , the best place and safest is the roller bar .
All other positions interact either with shadow or the boat usage or getting washed by waves .
Battery bank is 200ah lead and considering to replace it with 140 ah AGM

[Pete7]

I think you are on the right track and a frame plus good sized solar panel will ideal. My only regret is not doing it sooner.

Pete