Hi,
Do you know or have access to a compensation table for silicon diode Photo-current versus temperature? It is well known that the output Power of PV panels falls as they get hot, but is that not because the output Voltage falls (by about 2 mV per degree C for each diode junction). However, for a watts/m2 measurement, the sensors are normally operated in "short-circuit" (zero voltage) mode, where the output power must by definition (P = V * I) be zero.
In the absence of any better information, I think we have to use one of the Davis Solar sensors as a "Reference" Design and from post #12 in this thread, it appears that the Davis sensor does not compensate for the diode/panel temperature, nor report it (for the station to perform the calculation).
I'm still "researching" the most economical method for measuring Solar watts/m2, but am currently planning to use a BPW34 photodiode which seems well-specified, and with a good (Co-)Sine angular response.
Cheers, Alan.
Do you know or have access to a compensation table for silicon diode Photo-current versus temperature? It is well known that the output Power of PV panels falls as they get hot, but is that not because the output Voltage falls (by about 2 mV per degree C for each diode junction). However, for a watts/m2 measurement, the sensors are normally operated in "short-circuit" (zero voltage) mode, where the output power must by definition (P = V * I) be zero.
In the absence of any better information, I think we have to use one of the Davis Solar sensors as a "Reference" Design and from post #12 in this thread, it appears that the Davis sensor does not compensate for the diode/panel temperature, nor report it (for the station to perform the calculation).
I'm still "researching" the most economical method for measuring Solar watts/m2, but am currently planning to use a BPW34 photodiode which seems well-specified, and with a good (Co-)Sine angular response.
Cheers, Alan.