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Taz Abas
drabas@payplusco.com
213-252-4433

1000 watts/meter^2 * 1.9 inch * 1 inch * .10 = 0.1225804 watts

Probably enough that a good design could prevent loss thru self-discharge.

Of course, as an actual Arizona resident, the first thing that comes to mind is the fact that its a profoundly bad idea to leave any type of battery in direct sunlight for extended periods of time. It really wears them out!

The area of a C cell (excluding the end-caps of the cylinder) is about 0.004 square metres. So if the panel had perfect efficiency, and you illuminated it all with a full Arizona sun (~1000W/m^2), this battery would collect about 4mW of power. A typical NiMH today is about 2.9Ah, or about 3700mWh of energy (this is probably a high estimate, but not by much). So we can expect a total charge time of about 3700/4 = 925 hours = 38 days. The sun doesn’t shine for 24 hours — even in Arizona — so this 38 days is going to be more like 80 or 90 days in reality. Add in the fact only half of the cylinder is under illumination, and the circular geometry says reduces this by half again (cosine), and that the panel is going to be about 15% efficient, it looks like it’s going to take a several years to recharge the battery.

In essence, the average rate is about 0.1mW of power.

However, NiMH have a fairly high self-discharge rate of about 1% per day, after about a 5-10% drop on the first day (from a fully charged battery). Ignore the first day, we have: 3700*.01 = 37mWh loss/24hours = 1.5mW average. A discharge rate in excess of the trickle charge rate from these solar panels, suggesting the panel can’t even maintain the charge on a fully charged battery.