18-07-2015, 15:32
Hi,
Unless you put a resistor of about 1 or 2 ohms across the panel (which may produce values up to perhaps 100 or 200) then the results are MEANINGLESS. You must measure the "short-circuit" current from the panel, not an "off load" value. Then you need to calibrate the value against a known light level such as "clear sky sun" at your location.
The circuit doesn't need a particularly "good" Op-Amp, so you should be able to obtain a quantity at a cost of much less than $8 each. You just need to look for a "rail to rail" type (i.e. one that works correctly when the inputs and outputs are at ground potential).
Cheers, Alan.
(18-07-2015, 03:46)seth22 Wrote: rated at 1v 100mA under full sunlight
Unless you put a resistor of about 1 or 2 ohms across the panel (which may produce values up to perhaps 100 or 200) then the results are MEANINGLESS. You must measure the "short-circuit" current from the panel, not an "off load" value. Then you need to calibrate the value against a known light level such as "clear sky sun" at your location.
The circuit doesn't need a particularly "good" Op-Amp, so you should be able to obtain a quantity at a cost of much less than $8 each. You just need to look for a "rail to rail" type (i.e. one that works correctly when the inputs and outputs are at ground potential).
Cheers, Alan.