ZEMCH 2019 International Conference Proceedings April.2020 | Page 389
Figure 3. Variations of electrical efficiency against day hours.
Equivalent thermal efficiency terms are used to define the thermal performance of glass to glass
and glass to tedlar PV/T systems. Using dual‐fluid mode operation, the daily variations of equivalent
thermal efficiency for both cases are shown in Figure 4. Under similar operating conditions, the daily
average equivalent thermal efficiency for glass to glass and glass to tedlar cases are 81.98% and 80.21%,
respectively. Whereas, glass to glass PV/T system gives better results compared to glass to tedlar case.
This may be due to accumulation or trapped of infrared rays at the PV cells and the tedlar surfaces.
Furthermore, the useful thermal energy gains of a day for both cases are depicted in Figure 5. The net
heat gains very much depends on ambient temperature, higher the temperature gradient higher the
heat losses. The glass to glass PV/T system has maximum useful energy gain with daily average value
of 0.575 kWh, whereas energy gain for glass to tedlar case is 0.462 kWh. In context of thermal
performance the glass to glass PV/T system supersedes the glass to tedlar PV/T system due to high heat
dissipation capacity. Moreover, in glass to glass case the black painted back panel gets heated directly
from sun rays transmitting through non‐packing area of glass and also through conducted heat from
the PV cells.
Performance Evaluation of Photovoltaic/Thermal (PV/T) System Using
Different Design Configurations
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