Solar Water Heater Installation Angle

The angle at which you mount the collector should roughly correspond to the latitude of your location. For example:

- Melbourne, Australia has a latitude of 37° South - the collector should face north at an angle of 37°.

- London, United Kingdom has a latitude of 51° North - the collector should therefore face south at an angle of 51°.

You don't have to be too careful about mounting the collector at the exact suggested angle. If your roof angle is within 10° +/- of your desired angle, you can mount the solar collector flush against the roof surface. The additional trouble of adjusting the collector to an exact angle is not justified, as it will not result in a significant improvement in efficiency.

If you are using the solar collector for space heating as well as hot water production, or if you just want a greater solar contribution, you will need a system that will far exceed your summer heat requirements. Generally, in summer heating will not be necessary, in contrast to cooling. Unfortunately, solar cooling for domestic applications is not yet economically viable, so what to do with the extra heat? If you have a pool or spa, the excess heat can be used to supplement the heating. Turning off the pump and letting the collector stagnate is not ideal as high pressure and temperatures, and large volumes of exhaled steam can result (waste of water).

If you have no additional means of using the excess heat, then adjusting the angle of the collector can help reduce summer heat production. As can be seen from the diagram above, the sun is low in the sky during winter and high in summer. Solar smart home designs will take advantage of this by having large North or South facing windows (depending on your location), allowing for maximum absorption of winter sun, with large eaves or balconies to block the summer sun.

By increasing the vertical angle of the collector by about 20° latitude plus the location (i.e., 60° instead of 40°), greater winter performance will be experienced. This is because the collector is "facing" the sun (perpendicular - longitudinal angle). Due to the sun's greater location in the sky during summer, the collector will be around 40° from perpendicular and as such, heat output will be reduced as the collector is not fully "facing" the sun. This simple solution alone can reduce peak summer production considerably, thus reducing the problems associated with excessive heat production in summer.

The photo above shows an ideal example of an installation angle that optimizes winter, spring, and autumn heat output while minimizing summer output. The high angle not only maximizes exposure to direct winter sun, but also allows sunlight reflected off the snow to be absorbed. In summer, when the sun is high above, the exposed surface area is small, especially with the overhanging roof which partially shades the collector. In areas without snowfall (and a latitude range of 30-40°), a smaller angle than shown above would be suitable.

Note: For solar water heaters, optimal heat pipe performance is achieved in the 20-70° angle range. Although your location may have a latitude lower than 20°, this basic installation guideline should be followed. Horizontal angles of +/- 5° are acceptable and may be appropriate if the collector needs to be drainable (end port models only).