Sunday, September 12, 2010

Back in gadget design mode

Once again I need to tailor make something for Herbie, so I present to you (drum roll) . . .

A rough model of how to mount a tilting frame for the solar panel.

Optimum angles vary according to time of year, but generally speaking you get more power if you tilt the panel toward the south at an angle of between 40 and 60 degrees to the horizontal. About 48 degrees is a good average.

I haven't thought it all through yet but this rough paper model shows how a simple arrangement would work. The beauty of this idea is that it allows the frame to be tilted to the right or to the left according to which way the boat is facing. Of course if the boat is facing north south it won't help at all, except perhaps to face the early morning or late evening sun in summer.

The little hinged legs will be made out of aluminium strip from Wickes, simply rivetted at the joints like this.
This seems to make a nice stiff hinge (sorry for the blur, probably my hands trembling with excitement!).

What I have yet to work out is how exactly to attach the base frame to the vertical screws rising from the roof magnets (see earlier post). If the base fame were aluminium angle strip that might work. The problem might be stopping the rivets from catching on the side of the frame as the frame is raised.

My engineering pals (hint hint) may have elegant ideas.


Rick said...

One way to avoid the rivets rubbing would be to put slight joggles (double bends)in the strips.

You could mount the whole thing on a rotary turntable, or would that be going a bit too far?

Neil Corbett said...

Joggles sound easy enough. Good idea.

And your design for a cheap, simple, easy to make and install turntable would be???

Rainman said...

I agree with the previous comment!What about a means of locking the legs when up(and down)? Say screws and wing(butterfly)nuts at the centre elbows. As for a turntable, you will usually be able to find a suitable mooring round the next bend when cruising. But what about your permanent base? You'll have to specify east-west and no obstructions. David.

Neil Corbett said...

I had thought of a simple sleeve to drop over the joints and lock them straight, but I suppose joggles might stop that. Wingnuts seem a good solution although I'd be a tad concerned that they might slacken and let the panel drop. I don't mind if it drops gently, but if it came down with a bang it might damage it. Alternatively I could put a separate rigid prop in by hand once the panel was raised. Hmmm, thinking as I write, could secure that with a wingnut and bolt.

Keep thinking folks. Still waiting for panel to arrive. It was due on Friday.

Anonymous said...

Just a thought. In your model, the legnth of the hinged 'legs' compared to solar panel length doesn't seem to allow for a good winter tilt. I'm sure you'll work out exactly the angle you need to the sun in winter but so far, it looks like the angle I get with my flower-pot propping method, which isn't high enough in that season. What about a deck-chair design?
- Carrie

Neil Corbett said...

Thanks Carrie, I'm on the case. My model was just to test the mechanism. I will make the legs as long as can be without them clashing with each other when folded. I think I will get to about 50 degrees, which is not optimum but very close in terms of power loss. As Simon points out the difference between flat and best angle is only a 10% loss. In high summer of course the required angle can be as low as 18 degrees.