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EN-Rev IM/GN-BM-EU/1.93 Copyright © August, 2021. CSI Solar Co., Ltd.
www.csisolar.com
ANNEX B: GUIDANCE ON MODULE TEMPERATURE FOR SEVERAL LOCATIONS
The operational temperature of a PV module changes
during the day and also from day to day throughout the
year. The 98th-percentile temperature represents the
temperature that is larger than 98% of all the
temperatures, and consequently it is met or exceeded
only 2% of the time.
The 98th-percentile temperature is to be determined
from measurements taken on hourly-basis, or even
more frequently. For a standard year, the 98th-
percentile temperature would be met or exceeded
175.2 hours.
The operational module temperature is influenced by
the environmental temperature but also by how the
module is installed, as it may allow a more efficient
ventilation. The graphics below from IEC 63126 show
this influence.
For Open-rack it can be seen how the 70°C are never
exceeded in any of the locations, while for parallel to
the roof mounted modules (not in-roof) this value can
be surpassed for some locations.
Figure B.1 – 98th-percentile temperature for an open-rack, or thermally unrestricted
Figure B.2 – 98th-percentile temperature for a close-roof mounted
