| | Evacuated Tube Collector | Flat Plate Collector |
| | | |
| 1 | Rapid heat generation - vacuum seal prevents heat losses | Slower heat generation - no vacuum seal to prevent heat losses |
| 2 | Vacuum seal results in negligible heat losses during the daytime | Heat losses from the collector during the day-time are higher due to convection. |
| 3 | Negligible scaling of pipework within the heat-exchanger manifold | Small-bore tubing in the collector matrix can attract scaling, reducing system efficiency |
| 4 | Being cylindrical, the incidence of the sun's rays on the tubes and Heat Pipe is always at 90 degrees, giving maximum absorption throughout the day | Being flat, maximum absorption only occurs at noon, when the incidence of the sun's rays will be at 90 degrees to the collector matrix and fins |
| 5 | The vapourising / condensing process within the Heat Pipe maintains a satisfactory performance even in extreme cold conditions | Being a direct heat-exchange process, extreme cold conditions have a greater limiting effect, and the collector matrix is at greater risk to freezing |
| 6 | In locations where only diminished solar energy is available, sizing can be increased proportionately for satisfactory results | Where only diminished solar energy is available, the reduced efficiency requires dis-proportionately higher sizing, increasing costs |
| 7 | Maximum temperature range to above 95 deg.C | Maximum temperature range up to 80 deg.C |
| 8 | Advanced technology at competitive prices. | Old technology at higher prices |
| 9 | Hot water availability for a greater number of days through the year | Lower efficiency means hot water availability for a lesser number of days through the year |
| 10 | Heat transfer is direct from the vacuum tube to the cylinder's solar coil - no physical inter-connections between the tube and the heat-exchanger | Inter-connection fittings are required between the matrix and cylinder's solar coil, resulting in increased heat losses and component failure risk |
| 11 | The Collector panel is located onto the surface of the roof | The Collector panel can be installed flush with the roof |
| 12 | The Collector is assembled and installed in-situ on the roof | The Collector unit is fully pre-assembled, and may require lifting equipment to get it up onto the roof for installation |
