Hi all,
My south-facing roof has quite a bit of shade, due to trees that may not be possible to cut down (there is a brook behind the house, so they are in wetlands, and when I checked in 2011 the conservation commission seemed to think it wouldn't be likely to get permission to cut them down for solar). I've had 2 company come to look.
Company 1 used a SunEye (or similar device). Before getting the results, he seemed to think that it would work, but the results were "too low to read accurately" around 32%. He is suggesting using the north-facing roof, with a handful of panels on the south-facing roof where there would be the least shade (but was clear it wasn't ideal).
Company 2 used HelioScope with LIDAR, and seemed to think that it would work. They have a production guarantee (90% of the production estimate). From the numbers, it looks good -- nearly twice the estimated production per dollar spent compared to using the north-facing roof like Company 1 suggested. The company has been around for 6 years, and gets good reviews. It looks like the estimated production is somewhere around 60% of what it would be without shading.
Given that Company 1 didn't think it was worth using the south-facing roof, I'm a bit hesitant with going ahead with Company 2. Obviously they wouldn't offer the guarantee if they didn't trust the numbers, but if the results are really poor, it would be a hassle for me and cost them.
Any thoughts as to why there is a discrepancy like this?
-Scott
My south-facing roof has quite a bit of shade, due to trees that may not be possible to cut down (there is a brook behind the house, so they are in wetlands, and when I checked in 2011 the conservation commission seemed to think it wouldn't be likely to get permission to cut them down for solar). I've had 2 company come to look.
Company 1 used a SunEye (or similar device). Before getting the results, he seemed to think that it would work, but the results were "too low to read accurately" around 32%. He is suggesting using the north-facing roof, with a handful of panels on the south-facing roof where there would be the least shade (but was clear it wasn't ideal).
Company 2 used HelioScope with LIDAR, and seemed to think that it would work. They have a production guarantee (90% of the production estimate). From the numbers, it looks good -- nearly twice the estimated production per dollar spent compared to using the north-facing roof like Company 1 suggested. The company has been around for 6 years, and gets good reviews. It looks like the estimated production is somewhere around 60% of what it would be without shading.
Given that Company 1 didn't think it was worth using the south-facing roof, I'm a bit hesitant with going ahead with Company 2. Obviously they wouldn't offer the guarantee if they didn't trust the numbers, but if the results are really poor, it would be a hassle for me and cost them.
Any thoughts as to why there is a discrepancy like this?
-Scott
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