There are two things to consider when mounting your solar collectors: what angle to install them at and what direction they should face.
As mentioned previously, one of the advantages of evacuated tube collectors is that they are easier to mount at an angle than flat plate collectors. But what angle should you mount your solar collector and why? Here at Simple Solar for general purpose installations we try and mount the collectors so they sit at an angle between 45 and 75 degrees. As the graphs above and below show, this maximizes heat year round and so is ideal for water heating applications. With a properly sized system you can harness all your hot water heating energy from the sun year round.
Sometimes mounting a system between 45 and 75 degrees is simply not possible, due to issues with building codes or lack of suitable solar space, or desired, for instance when space heating is the main purpose for the solar system. In these cases other mounting configurations, such as a vertical wall mount, are more feasible. As the chart below shows, a system that sits vertically will still provide plenty of heat during the winter when the sun is lowest, and this is ideal for space heating applications as winter is when we need to heat our buildings the most.
In order to maximize your solar gains throughout the day you’ll want your collectors facing southwards in the northern hemisphere and northwards in the southern hemisphere. This ensures that your collectors will always be facing the sun as it tracks across the sky. Due to the spherical nature of evacuated tubes they can be positioned up to 45 degrees off south and still function at 95% efficiency however more drastic angles will result in poorer solar performance. Collectors facing eastwards will receive plenty of energy in the morning as the sun rises but little to no energy after solar noon. The reverse is true for collectors facing westwards; they’ll receive plenty of energy as the sun sets but almost none before solar noon.