Performance of the GTAC PV System for 1999
This page contains measured performance data for the GTAC PV system for the year 1999. Click on any month on the left to obtain that month's data.
- AC Energy Production [Mwh]
| Month | Measured | Predicted* |
| January | 20.7 | 18.7 |
| February | 25.6 | 22.6 |
| March | 33.9 | 34.0 |
| April | 37.3 | 39.7 |
| May | 46.4 | 46.9 |
| June | 37.9 | 42.9 |
| July | 40.6 | 44.0 |
| August | 43.0 | 42.5 |
| September | 35.3 | 31.7 |
| October | 11.2** | 32.3 |
| November | 0.0** | 23.0 |
| December | 14.8 | 18.8 |
* The "predicted" AC energy production for each month was found using the computer model PVFORM 3.3, with the TMY providing metheorological data.
** During October, failure of a cooling fan in the PCU led to system downtime due to overtemperature shutdowns. The inverter was disabled in November, and was enabled again on December 3, when a new fan was installed.
Mean daylight-hours module temperature [oC]
| Month | Measured | Predicted |
| January | 18.5 | 10.5 |
| February | 22.2 | 12.3 |
| March | 24.2 | 19.3 |
| April | 32.5 | 28.5 |
| May | 38.5 | 33.3 |
| June | 38.8 | 35.5 |
| July | 44.0 | 37.4 |
| August | 46.6 | 38.4 |
| September | 39.9 | 32.2 |
| October | 31.9 | 26.8 |
| November | 27.6 | 18.6 |
| December | 19.2 | 12.0 |
* 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]
| Month | Measured | Predicted |
| January | 2.63 | 3.15 |
| February | 3.55 | 3.43 |
| March | 4.47 | 4.68 |
| April | 5.01 | 5.39 |
| May | 6.09 | 6.31 |
| June | 5.16 | 5.98 |
| July | 5.58 | 5.98 |
| August | 5.98 | 5.76 |
| September | 5.13 | 4.43 |
| October | 3.93 | 4.29 |
| November | 3.19 | 3.11 |
| December | 2.70 | 2.44 |
- Average sunlight-to-AC-power efficiency [%]
| Month | Measured* |
| January | 8.11 |
| February | 8.24 |
| March | 8.22 |
| April | 7.92 |
| May | 7.83 |
| June | 7.79 |
| July | 7.55 |
| August | 7.38 |
| September | 7.59 |
| October | 7.57 |
| November | N/A** |
| December | 8.11 |
* 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.
** The inverter was disabled during November, due to fan failure.
- Typical DC voltage range [V]
| Month | Measured |
| January | 360-450 |
| February | 360-440 |
| March | 350-440 |
| April | 310-425 |
| May | 330-425 |
| June | 330-405 |
| July | 320-405 |
| August | 325-400 |
| September | 325-430 |
| October | 350-445 |
| November | N/A* |
| December | 380-445 |
* The inverter was disabled during November, due to fan failure.