From: paul dove via EV <email@example.com>
>What is the wattage on that Lee. I calculate 3Watts. 0.25 X 12 V = 3 W
>Harbor freight sells a 15 watt panel.
>15 Watt Solar Panel
I don't recall what wattage was claimed. But many of these panels will do
things like advertise the short-circuit current, and open-circuit voltage, and
multiply them together to get the claimed wattage.
That's completely bogus. First, it assume perfect full sun, at the optimum
angle, and a low ambient temperature. Second, you can't even get half the
short-circuit current into a real load. Third, the voltage under load is
substantially less than the no-load voltage.
The more honest vendors will provide a voltage, current, and wattage under
realistic conditions, driving an actual load.
Even then, you have to consider how you will actually use the panel. In my
case, the PV panel sits horizontally, on the shelf under my car's back window.
Thus it is never at the optimum angle, the glass reduces the light intensity,
and the temperature inside the car is always hotter than ambient.
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