Light measuring instrument

GreenPowerManiac

Is there a UV or light measuring instrument out there sensitive enough to measure for solar power ?

The next question is, can it be done for a reasonable price ?

BB.

Re: Light measuring instrument

From several other threads:

BB. wrote: »

There are several ways of getting an answer...

One is there are several moderately priced weather stations (LaCrosse and others) out there that have optional solar irradiance meters. Many come with a USB to PC interface for data downloads

Or, just get a small solar panel that is the same type as your "main panels" (i.e., silicon mono or poly crystalline) and measure the output current with a DVM (short the output with your amp meter). The output current is pretty porportional to the irradiance (over time and temperature).

In this thread "Jeff Fendison" offered on his website information on how to build your own irradiance meter (basically short the output of a small solar cell with a current sense resistor and a panel DVM)--and he also sells kits that will log the data over months just using a 9 volt battery and a usb dump to a PC.

http://www.microcircuitlabs.com/SIM.htm

I have not used any of his equipment or had any discussions with Jeff, but his kit/turnkey logger looks very reasonable.

In the end--you (TnAndy) have a Grid Tied Power system--and as long as everything is working OK--your system pretty much is logging the solar irradiance + temperature coefficient to a reasonably accurate number.

If you have logging software for your system--can it log Solar Array Current? That will be a much more accurate representation of Solar Irradiance vs the Array Power reading:

A 10C (18F temperature offset) will affect Pmax by -3.4%. The same offset will only affect Isc (~Imp) by +0.17%

Both numbers are probably more accurate than you can expect from a "garden variety" GT Inverter's data panel readings (many systems seem to be off in the +5-+10% range--read more power than is really generated--The Xantrex, from what others have said, is probably closer to the +/- 1-2% accuracy range--"Nobody is unhappy when their system produces more power than nameplate" :roll: ).

Don't get too mired in the data and assume that you have better than ~10% accuracy unless you have done some calibration/conformations.

-Bill

quid_non

Re: Light measuring instrument

Jeff @ Microcircuits is Great!
I have purchased several of his items including the solar logger and inexpensive irradiance meter kits. Delivery was really fast and assembly was straight forward (if you can solder).
I highly recommend him - he is very responsive anf great to work with!:D