PV Performance Tests Richard Perez and Bob-O Schultze PDF Download
PV Performance Tests. Each module tested has two sets of data presented here. Each PV module has a table giving the manufacturer’s specifications and our “in the sun” measured data. Each module also has a graph showing the actual current vs. voltage measurements we made.
Here is an explanation of the short-hand terms used in the tables.
• “Isc” is module short circuit current, in Amperes.
• “Voc” is module open circuit voltage, in Volts DC.
• “Pmax” is maximum module power, in Watts.
• “Vpmax” is the voltage which the module develops at its maximum power point, in Volts DC.
• “Ipmax” is the current the module produces at its maximum power point, in Amperes.
• “PV Temp” is the temperature of the module (back side), in degrees centigrade (°C.).
• “Insolation” is solar insolation, in milliWatts per square centimeter.
All of these terms and units are standards used by the entire photovoltaic industry to rate their products. We used manufacturer’s ratings at a 25°C. (77°F) module temperature.
In the comparison tables that follow:
• Rated value is the maker’s performance specifications.
• Measured value. Our measured data.
• Percent of Rated”. A comparison of our measured results with the maker’s ratings.
The graphs show module current vs. module voltage. In order to better present this information graphically, we limited the voltage axis of the graph to 12 to 18 Volts. We did, however, log all the data from 0.5 Volts to the module’s open circuit voltage. If anyone wishes a complete electronic copy of all of the data we took, you can find it on the Home Power BBS at 707-822-8640 or send a floppy disk (please specify Mac or IBM) with SASE return mailer to Richard Perez at Home Power. Most of these modules have had their performance measured by us during the summer of 1991.
We reported on their hot weather performance in Home Power #24, page 26. What follows here is another hot weather test on the same group of modules. All are now older and we are looking for degradation in module performance over time. We found no degradation that we could measure in any of these modules. In fact, some of them actually tested better than they did four years ago!
Please note that these are hot weather tests. PV modules are rated at a 25°C (77°F). temperature. The data we took here was from modules whose temperature was from 49°C (120°F) to 55°C (131°F). Heat causes the PV’s maximum power to decrease. This is why almost all of the modules do not make as much power as their maker rated at 25°C. All modules are listed alphabetically by manufacturer’s name.