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Panels on southeast roof worthwhile?

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Panels on southeast roof worthwhile?

Posted 05 Jan '17 05:48 PM

We were only able to get 8 panels on northwest and 2 on northwest. It's not really enough. I'm considering if it's worthwhile adding 4 to the southeast or not. 20 degree roof will get sun perhaps 65% of the day in summer, not sure about winter though, probably 35% at a guess. Someone else may have a better idea of these figures. Micro inverters being used.

Cheers,
Ross.

RE: Panels on southeast roof worthwhile?

Posted 22 Jan '17 03:26 PM

You're thinking the panels will be parallel with the roof, for aesthetics?

I don't know where you are, nor what your sun angles are, but as I see it, sun angles are the primary consideration. Maximum output happens when the panels are exactly perpendicular to the suns rays.

Some useful info in this PDF: http://www.sunsmartschools.co.nz/Guidelines_Under_Cover.pdf regarding NZ sun angles winter, summer and solstice.

If parallel with a 20 degree pitched roof, in summer, the southeast panels will be starting at about a 35 degrees (vertical) disadvantage compared to the northwest ones. At midday, even in summer, the sun angle to those panels will then be quite low, and your yield will be insignificant, and simply not worth the money. Even at 8am in summer, the panels will be at an unfavourable angle to the sun, and the sun intensity will still be low at that time.

Not worth it, in my view.
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