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Performance of the GTAC PV System for 1997
This page contains measured performance data for the GTAC PV system for the year 1997.
It should be noted that, during January, about 20% of the PV array was disconnected from
Jan. 1 to Jan. 15 as part of an experiment. Also, in the beginning of May, the system was
deactivated for a short time so the Aquatic Center's main transformer could be moved, part
of the continuing post-Olympic conversion of this space back to Georgia Tech use
- AC Energy Production [Mwh]
| Month |
Measured |
Predicted* |
| January |
18.3 |
18.7 |
| February |
19.6 |
22.6 |
| March |
39.2 |
34.0 |
| April |
42.3 |
39.7 |
| May |
38.6 |
46.9 |
| June |
30.1 |
42.9 |
| July |
32.0 |
44.0 |
| August |
38.1 |
42.5 |
| September |
31.8 |
31.7 |
| October |
29.6 |
32.3 |
| November |
20.7 |
23.0 |
| December |
17.1 |
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.
| Month |
Measured |
Predicted |
| January |
15.9 |
10.5 |
| February |
19.6 |
12.3 |
| March |
31.2 |
19.3 |
| April |
31.3 |
28.5 |
| May |
34.6 |
33.3 |
| June |
36.1 |
35.5 |
| July |
44.2 |
37.4 |
| August |
41.2 |
38.4 |
| September |
38.9 |
32.2 |
| October |
31.5 |
26.8 |
| November |
18.5 |
18.6 |
| December |
14.1 |
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 |
3.26 |
3.15 |
| February |
2.94 |
3.43 |
| March |
5.58 |
4.68 |
| April |
6.09 |
5.39 |
| May |
6.34 |
6.31 |
| June |
5.74 |
5.98 |
| July |
5.98 |
5.98 |
| August |
5.57 |
5.76 |
| September |
5.02 |
4.43 |
| October |
no data* |
4.29 |
| November |
no data* |
3.11 |
| December |
no data* |
2.44 |
* Difficulty with the pyranometers began in October and eventually necessitated
their being sent to the manufacturer for repair and recalibration. This is why "no
data" appears for the last month of 1997 in the above table.
- Average sunlight-to-AC-power efficiency [%]
| Month |
Measured |
| January |
10 |
| February |
9.50 |
| March |
8.50 |
| April |
8.25 |
| May |
8.25 |
| June |
7.60 |
| July |
7.00 |
| August |
7.10 |
| September |
7.60 |
| October |
no data |
| November |
no data |
| December |
no data |
* 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]
| Month |
Measured |
| January |
350-440 |
| February |
350-415 |
| March |
345-430 |
| April |
345-425 |
| May |
335-420 |
| June |
350-410 |
| July |
325-400 |
| August |
320-405 |
| September |
330-410 |
| October |
330-420 |
| November |
360-440 |
| December |
375-440 |
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