Editing 2009-026

From: alexander bridge <alexander.bridge@gmail.com> Date: 2009-08-29 (Sat) 16:50:21 ADT Subject: Roof Pitch for Solar Greetings- Planning to build a garage with a pitched roof with the idea of adding solar panels next year. L We live in Tracadie, NS. Is there a 'perfect' roof pitch for this area? 12-12, 12-10? Thanks! Alexander Answer: Greetings: Your latitude in Tracadie is just over 45 degrees north (45.6 degrees). For the highest annual total solar energy collection, a good angle is about equal to the latitude, so 45 degrees, which is 12-12. I would even tend towards a bit steeper (like a rise of 12 in 10), because this will slightly increase the winter solar collection, due to the lower sun elevation above the horizon in winter. I tend to tilt them a bit steeper than the latitude angle for two reasons - (1) In winter the days are shorter and the sun is not as strong, so I'd want to tilt them up a bit more to maximize winter collection. (2) People often need more energy in winter. You haven't mentioned whether they are for heating the space, heating the domestic hot water or for making electricity, but in most cases more energy is used in winter. Of course, you don't necessarily have to mount the panels at the same angle as the roof - you can tilt their top ends up a bit on a stand if you want to. But it can be convenient to attach them directly to the roof at the same pitch as the roof. However, if they are evacuated tube water heaters one disadvantage of mounting them against the roof, at the same pitch as the roof, is that in winter snow will collect between the evacuated tubes and the roof, which will decrease their performance. If they are flat plate collectors, this will not be a siginificant issue. Regards. AnsweredQuestion

Summary:

This change is a minor edit.

Username: