Auto-tilting solar panels

[Ric]

I was recently talking to a French yachtsman who had his Ovni equipped with solar panels that automatically self adjusted their tilt to the sun's declination. He told me that the gear was "anglais", but apart from that he didn't know the manufacturer. Does anybody know the manufacturer?

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[euroe]

Hello Ric, this Robert Tucker sloop is the first vessel I've had without a main engine that gives 12 Volt battery charging power. Could you possibly advise me what size sloar panel would suit my boat that carries:- VHF, Echo Sounder, Simrad T10 Tiller Pilot, GPS Plotter and the usual Nav' and accomodation lights. None of this stuff makes great Amp' demand and I'm pretty economical using it, but I don't want to be too economical when acquiring the Panel to cope with it. Greatly appreciate any advice.

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[jerryat]

Hi Ric!

Do post any answer you get to this post! I've chewed over exactly this idea many times over the last few years when scrambling to adjust the panels on my boat, wishing some little automatic motor was doing it for me. I've got a horrible feeling that the amps gained would be more than offset by the minimum two motors needed (vertical and horizontal angles) not to mention keeping the things waterproof, protected from damage and so on.

I wonder if those your Frenchman saw were 240v though, i.e. for use with home solar systems?

Still, if someone out there does have the solution, I'm sure there would be a reasonably good market for it.

Good sailing!


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[Talbot]

I thought about these when installing my panel, but rejected them. I wanted a robust system that would last a long voyage, so installed it in a solid frame above my davits. I have tilted it aft at 5 degrees so that I get a reasonable run off from water, and it gets a better look at the sun from astern of the boat, whereas the sail will obscure from the bows. This is a 180w panel in its own ali frame and feeds through a regulator which fills one battery bank before doing the other. I will be installing a duogen as well,, and by the time I have LED nav lights, I anticipate that supply will be equal of demand.

There is only one way to work out what sort of panel/wind charger you need, and that is to do an energy budget. It is reasonably straightforward, but will require some research. Start by listing all your electrical equipment, and then work out how many hours you will use it in a 24 hr period, then work out the amps required for use multiply the amps used by the hours used, and add these figures for all your equipment. You will have some items that may not be in use everyday, but will be used occasionally (e.g. windlass). work out average use over a week, and then divide by 7. The final total will surprise you!

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[Ric]

The system on the French Ovni definitely worked on 12v. The system only worked in pitch (relative to boats axis) - which is all you really need if you are sailing the trade routs which are mostly east-west. The system hardly drew any current, as it just adjusted the angle every 15mins or so by just a few degrees at a time.

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[BobOwen]

I did a search a month or so ago on the subject of solar panels and came across a research article investigating tilting panels. It investigated the different power outputs of a panel fixed horizontally versus a panel following the sun. (All other aspects being equal, such as sail shadow, direction of travel etc).

I don't have a link, but I'm sure you can find it or similar. The results were quite surprising, inasmuch as that a tilting panel versus a fixed horizontal, gave only marginal differences in output. The figures obtained took into account the typical sunshine figures for any fixed position, the output available early and late in the day etc. The conclusion was that a larger fixed panel was as good as a smaller one with auto tilt mechanisms. A non tilting system gave something like 85 - 90% of the overall output of a tilting system.
By that, the results showed that if you wanted output A, then select panel A+ rather than A with a complex auto tilt mechanism. Sounded like supreme good sense to me, as a I'm great believer in KISS (Keep It Simple, Stupid).
Might be worth reading up a little more, other than tilting panel manufacturers sites .....


<hr width=100% size=1>Beer - its not just for Breakfast you know.

 

[Egbod]

I have fitted my small solar panel on a adjustable angle bracket which I can also rotate. This is fully manually adjustable. The solar panel is left flat when the boat is on her mooring and adjusted if I feel like it when I am on board. Most power use is when I am on board so it works well.

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[William_H]

Hello euroe The bquestion of solar panel size for your boat is linked to your sailing habits. Firstly you need a battery which at 50% rated capacity will provide all your current needs for your longest expected voyage. You might be well to not try to cater for really long voyage that may or may not happen as in this eventuality you might like to hire or buy a generator. Just estimate on your usual longest voyage. It is probably not safe to rely on solar power to provide power for an infinitely long period unless you are sailing in the tropics. The sun is not that reliable in UK. If as I imagine you are one who sails once per week or once per fortnight then you are looking for solar power that will recharge your battery over a week oryou may even be willing to put up with a recharge over a longer period if the battery is discharged. So count on about 8 hours ( summer)per day of output averaging about 60% of the rated watts divided by 12 (volts). If you are on a swing mooring you will get less current because you can't tilt to the south. Panels are rated at output amps multiplied by volts however the volts they calculate at is usually 17 being max volts out.
Don't be too afraid to under rate your solar panel as the price goes up in proportion to the wattage and so there is not so much money wasted if you have to buy another panel. Too many or large panels can be a menace to mount out of harms way. I have settled on a mounting with bungees on the boom sail cover and remove it before I go sailing. I have had them on front hatch cover and they get damaged or corroded. No don't expect them to last forever but they are good for the weekend sailor.

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