I have an ABC watch from Casio that is also an altimeter, barometer, and compass. I'm fascinated that all these features are powered by solar, which makes me curious:
How much power is generated from a typical solar-powered watch?
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Not only that - they have rather complicated watches that are claimed to run of a single lithium cell fro ten years http://electronics.stackexchange.com/q/41582/3552 – sharptooth Dec 11 '14 at 09:44
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There are two main factors which will affect the power you can get from solar.
- How much power the solar radiate on your watch's solar panel. Per this link, in summer day, 40 degree latitude, there will be 600W/m^2, and in winter, there will be 300W/m^2.
- The efficiency of your solar panel. This depends on many factors, typical may be less than 15%, according to this link.
Assume a 600W/m^2 solar power and a 15% efficiency, 1 cm^2 solar panel:
$$ 600W/m^{2} \times 0.15 \times 1 cm^2 \approx 10mW $$
diverger
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Solar power gives roughly 100W/m^2. Let's say the watch has 1 square cm of solar panels. That's 1/10,000th of a m^2. That gives us an upper bound of 10mW. Given that that number is for outdoor solar panels pointed at the sun, it's fair to say that the indoor average will be much less than that, so I'd estimate about a milliwatt.
pjc50
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100W/m² is not a bad figure at all. A rule of thumb is the sun delivers 1000W/m² and panel efficiency is usually between 5% and 15%. – Morten Jensen Dec 11 '14 at 09:33