Posted by schooner on February 21, 2006, 9:24 am
Here is a 1-wire device that measures solar radiation:
I may look at getting one of these once I get my other 1-wire temp loggers
Not sure if these guys have a solar meter add-on or not:
Posted by nicksanspam on February 21, 2006, 12:47 pm
How about a side-by-side calorimetric calibration? Let the sun also shine into
a 70 F water tank for a few minutes and measure the temp rise...
Posted by nicksanspam on February 21, 2006, 12:39 pm
Sounds like alt.solar.photovoltaic.
Posted by schooner on February 21, 2006, 12:43 pm
Well its in regard to trying to get a reading of sun strength for
determining solar air collector performance so I would say it applies here
Posted by spinning on February 25, 2006, 9:56 pm
Wayne, you were measuring the open circuit voltage (Voc). Do you have
an electrical load that runs on 18 to 20 volts?
Here's one way to measure the power, disconnect the meter, move the
meter dial and test lead to measure current, often labeled "10A", for
10 Amps (max). Then reconnect the test lead and measure the short
circuit current (= Isc) (Note: I'm pretty sure this won't hurt the
panel but you may want to double check). Then to calculate a suitable
load resistance, R ~= Voc/Isc (ohms law). Find a resistor with this
value, and one that is rated for Voc (volts) x Isc (amps) = Power
(watts). Then remeasure the voltage and current, since they will drop
about 10% under load, and recalculate the power output. If you don't
have a resistor, use any relatively stable load using 18-20 volts.
Note, to measure the current, you will have to (disconnect the load)
and put the meter in series with the load and the panel.