The panels seem to be very optimistically rated, I believe. The best commercially available panels seem to be around 16 to 18% efficient in practice and the usual insolation figure used for rating panels (which equates to full sunshine across a large part of the globe) is 1000 watts per square metre. This means that an 18% efficient panel will deliver about 180 watts per square metre in bright sunshine.
At the equator peak insolation gets to about 1400 watts per square metre in bright sunshine, so a panel could get to an output of around 250 watts per square metre peak there.
Converting these figures to US measurements gives a rated maximum of about 17 watts per square foot for the normal peak rating manufacturers use or about 23 watts per square foot for the absolute maximum at the equator.
In practice, panel output will be a lot lower than the manufacturers figures, based on my experience with my solar powered boat. I find that I get about 1/3rd the rated output from my panels in the summer months, much, much less in winter, maybe only 1/10th of the rated power on average, because my panels are virtually horizontal (they are on top of a canopy) and also because I live around 50 deg N, where insolation levels are lower due to the low angle of the sun through much of the day.
The figure you've quoted, of 235 watts per square foot isn't achievable anywhere in the world, as it exceeds the power available in sunlight even from a 100% efficient panel. 235 watts per square foot equates to about 2,500 watts per square metre, more than double the sunlight power that's available. It'd be good to check with your supplier, as I have a feeling there may be an error somewhere.
It sounds like an interesting project, though.
Jeremy
--- In electricboats@yahoogroups.com, "mark.jumaga" <markj@...> wrote:
>
> The hulls are now being constructed, this vessel WILL be powered by electric motors. I will be using the largest (235 w) power per sq ft solar panels I can find. The rest of the system has not been specd yet, but I have a lot of research (3 years). Comments please on components and or complete systems. I am not going to buy a retail packaged system due to cost. Recommendations for batteries, motor type, controllers, voltages of the system, generator, regeneration, drive type, caveats, experiences.
> I expect a minimum of a 30 HP drive for each side, probably closer to 50. Large prop so drive pod is not possible.
> Thankyou so much. A brief response is sufficient if you don't have time to comment.
>
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