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How important is it that the collectors face due South?

 

Q:

How important is it that the collectors face due South?

A:

Ideally the collectors will face due solar South, angled at the latitude of the location, to achieve the best year-round performance. However deviations of 30 degrees either side of solar South and plus or minus 15 degrees in angle from the latitude will only cause a small loss in performance. Of greater significance is the effect of shade on the collectors four hours before or after solar noon. The position and height of trees and structures must be taken into account when locating the solar collectors. Consideration must be given to the effects of snow accumulation on or around the solar collectors. Evacuated tubes will not shed frozen rain or snow until air temperatures rise above freezing, and if placed close to the roof can allow snow to pack in between and over the tubes - severely reducing their performance.


If an off-optimum orientation has to be used, it often makes much more sense to add another solar collector than it does to build a complex roof rack to face the collectors towards the South. Normally, not only do these racks look ugly and have the potential to cause problems, they also can cost as much as adding another collector. Usually in these situations, you will get more heat by installing another collector than by using a angle-correcting rack.


Remember: Solar water heating collectors must be mounted securely in order to do a good job and last a long time.