Figure 1 Heat collection plate. For PVT1, the plate is made from aluminum plate and the copper tubes are used as the flow passage. The plate and the copper tube is glued together and a aluminum foil with adhesive surface is adhered on the surface of the plate and the tube to enhance the heat transfer.
Thermal grease is applied between the contact surfaces.
This is due to a high heat loss at high operating temperature. See Figure 2. This is acceptable since PVT3 is an unglazed collector. The present study is different from the previous one 2 in that, a commercial polycrystalline PV module is used for the packaging and the thermal performance rating is based on the testing method of conventional thermosyphon solar hot water heater. We think that further improvement is still possible.