Small-scale electricity generation through thermal harvesting in rooftop photovoltaic picogrid using passively cooled heat conversion devices

摘要

Investigated in this study is harnessing the heat energy absorbed by photovoltaic (PV) solar cells for electricity generation, in order to boost the electric power output of rooftop PV power system, without expending on cooling the energy conversion devices. An experiment was carried out in which a metallic plate was attached to the back of a low rate rooftop PV installation to capture the waste heat of the PV array and evenly distribute the heat to the conversion devices. Four commercial thermoelectric generator (TEG) modules were attached to the plate for the conversion of the heat to electricity. The modules were passively cooled and connected in parallel. Outputs of the PV array and the TEG bundle were obtained on a data logger while the experiment lasted for 11 weeks during a sunny season in Nigeria. Voltage and current up to 2.5 V and 4 A, respectively, were obtained from the harvested heat, while the PV-TEG combination operated at higher efficiency than that of the PV alone. Potential of rooftop PV system in hot climates is thus maximized by the passive cooling. The approach could be improved further using metal plate with higher conductivity.