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Has anyone on this forum rented the Suneye solar analysis tool, rather than purchased one? for someone who has made up his mind to "go solar", no matter what the cost, the purchase of a $1,200 instrument can be included in the total cost of the project. For someone like myself, who has decided that solar is a "bucket-list" item that must pencil out savings for 7 years, that instrument adds considerable cost to the project. Alternatively, have any of you folks collaborated ( as neighbors, perhaps, in a gated community ) in the purchase of said instrument, to spread it's cost over several projects?
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Just install only where there's no shading.
I looked at what my choices were, and I decided that the right price/performance for me is to just eyeball it (look at the roof at different times of the day a few months apart and call it good.) Since I'm installing optimizers, it'll mean the panels that get shaded won't have as quick of return as the unshaded ones - but one panel shaded won't be as detrimental to the whole installation.
The thing that's a close second (very close second - and I might still change my mind) is a $16 app that you install on your smartphone/tablet and use to figure out the horizon. (I think you basically sight along it and tilt the phone to trace the horizon as you rotate from left to right (east to west) -
That sounds a bit pricey, even if shared amongst a few households. Although I was tempted to buy a used Solar Pathfinder on craigslist for about $150, which is a much more economical instrument but perhaps just as effective. And it is the same as my installer used. Ultimately my installer shared some of the photos from the Pathfinder as well.
I have some very localized shading from a large tree 10 feet to the west of the house, and when I wanted to do some more specific measurements of which branches I need to have trimmed, I've been using the free iPhone Skyview app to survey the foliage...Comment
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Cheap alternative to shade-mapping instruments
My instrument question was mainly posed, because the Suneye & similar instruments calculate solar insolation at target locations selected for possible array installation, taking account of actual real-time shading, as well as local geographic data. I don't know anything about the iPhone App, but I doubt it is very sophisticated. Last year, when I started putting together detailed plans for a solar array, it was obvious that a roof-top array was not practical, due to structural and shading issues. With 3/4 acre of open "unused" land behind ( south ) of the house, that seemed to be the logical area to place the array. The only question, was where on the ( roughly ) 150' x 180' plot to place a 13' x 33' rack of 22-24 panels. The nearer to the house, the worse the E-W shading, & the farther up the hill, the worse the south-shading near the ridge-line. Two 100' southerly trees are mine, and can be cut down, but some are county wind-break trees. Mid-lot is fairly clear to the east, but somewhat shaded by tall, but remote Eucalyptus, and shorter but "protected" Live-oaks on my property, that I can trim, but not remove.
Online, I acquired a useful chart, provided by the University of Oregon, that takes account of local latitude/longitude, and provides a means for plotting local shading, as it will appear on the proposed site, throughout the day & year-round. I used copies if this chart to determine shading at several possible site locations, but provides no means for calculating actual insolation. There is no provision for classifying soft vs. hard shading, or calculating the effects of obstacle vs. distance.Comment
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I believe the $16 app does do a % shading degradation on a per month basis, which you could then plug into the calculator of your choice (ex. pvwatts). It probably doesn't do "hard" and "soft" shading. Does Suneye?
I'm not sure what you mean by "obstacle vs. distance" - it seems to me that you're just getting a horizon line to calculate when the sun is blocked by the things on the horizon. So it doesn't really matter if that obstacle is 4 feet away, 40 feet away, or 400 feet away - what matters is that it's blocking the sun starting at XXX time in July, starting at YYY time in October, and starting at ZZZ time in December.Comment
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I probably didn't use the correct terminology, in describing the effect distance has on the amount of insolation a solar panel receives from the sun, when it is "blocked" by a fixed object. Wide, solid objects like houses, sheds & chimneys in an urban/suburban environment are usually so close to the panel array, that the sun generates a "total shadow" on the array, as it passes behind the object. On the other hand, a tree may not generate such a total shadow, provided that it's elements ( branches, trunk & leaves ) are relatively narrow, compared with the apparent width of the solar disc at "rural distances". A good example in my "back yard", is the 110' Monterey Pine at the top of my yard. When I stand 20' North of it & observe the sun directly behind it, the sun is totally blocked out by the 16" trunk. When I go down the hill, and observe the sun behind the same tree at a distance of 130', only about 1/5 of the solar disc is obscured by the tree trunk. I can take advantage of this effect by siting my array 80' from the Live-oaks on the Western edge of my property, and "trimming the hell" out of them, so they appear relatively porous. By using the procedure described on the website www.thesolarplanner.com/array_placement3.html, I was able to obtain satisfactory qualitative values for daily/yearly insolation.Comment
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