1998

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Performance of the GTAC PV System for 1998

This page contains measured performance data for the GTAC PV system for the year 1998.
In general, the performance of the GTAC PV system has been very good. We
have had a few minor difficulties with equipment, but the biggest reason for system down
time has been that, since this is primarily a student-run facility, it takes us some time
to learn about what the problem is and figure out how to fix it. But we’re getting better,
and the system performance reflects this.

• AC Energy Production [Mwh]

^* The "predicted" AC energy production for
each month was found using the computer model PVFORM 3.3, with the TMY providing
metheorological data.

^** During May, the system was down for 17 days due to a
failure of a current transducer in the PCU. During June and the first part of July,
failure of a cooling fan in the PCU led to system downtime due to overtemperature
shutdowns.

• Mean daylight-hours module temperature [^oC]

^* The measured mean daylight-hours module temperatures are typically
a few degrees higher than the predicted ones. We believe this is due at least in part to
the roof curvature, which impacts air flow above and beneath the array, and standing
seams, which may impede airflow behind the modules more than expected.

• Daily average solar energy flux [MWh/m²/day]

^* Difficulty with the pyranometers began in October 1997 and
eventually necessitated their being sent back to the manufacturers for repair and
recalibration. They were replaced on the roof in very late January 1998, and this is why
"no data" appears for January in the above table.

• Average sunlight-to-AC-power efficiency [%]

^* This "average" efficiency was found using only the times
during which the system’s DC power was higher than 80 kW. For lower DC powers, sensor
inaccuracies cause the values to be suspect.

• Typical DC voltage range [V]