Solar reflection of a photovoltaic system

For the roof surface of a geo-located model shown in the image, I would like to determine the solar reflections over the course of the year that may be disturbing the neighbors. What would be the easiest and most informative way to do this?

The obvious would be to use a renderer like V-Ray to reflect sunlight off the collector to see where it falls. In fact, V-Ray 5 now has a real time game type renderer. Couldn’t you move the date and time sliders around and see the effects in real time?

Without a renderer, maybe it would help to have a SketchUp model of the sun’s paths in the sky. I’ve seen 2D charts over the years. Has anyone created 3D ones? Mirror the whole model about the reflective plane, make it a window, and from any given point see what part of the sun’s paths you see of the reflected model through the “window” of the collector?

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Maybe curic sun can help?
Of course, the sol purpose of the panels is to absorb as much sunlight as possible and you can also apply them with a coating, from what I have heard (we get 2-3 offers a month)

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In general, if your neighbours are not tower blocks. it seems to me that the sun won’t be high enough for the reflections to go downwards. We recently had to skip fitting solar panels on a project that is very near an airfield.

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Yes, I’ve used it to see the shadows at a short winter day:

but there isn’t a reflection part and the “show sun” disappears when you switch to SketchUp, so you can’t use the position to manually construct the reflection either.

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For the closest house I constructed two example light beams, to land there the sun would have to come from the direction of the two marked directions, according to Curic’s plugin much more perpendicular from above than is ever reached over the year.

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What is your latitude and what is the angle of the roof?

Something along these lines would be helpful:

  • Marking the reflector area
  • Creation of a reference surface (here hemisphere)
  • Color coding of the sum of hours with reflection in the direction of the reference surface

Latitude: 51.5121N
and 45° slope

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…then you could go to the position of the reflector and see if there are critical reflections for others:


The dome idea is a good one and you could get a reasonable number of samples to get an idea. It would be easier if you were talking about a mirror on the roof.

In our parts (60.4N) we mainly get glare from reflections from neighbours’ windows, especially in the winter when the solar angles are low.


A mirror surface would probably be sufficient as a good approximation and worst case scenario.

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Is there a plugin or another way to create a (construction) line in the direction of the current sun position?

Sun position/course by Gabriel Miller (tested in SketchUp 8)

and in SketchUp 2021


Is it just those two buildings you are concerned about? If so, if VRay does not work/is not an option, and if you don’t find a plugin to do what you want, your sunpath suggests there are very few possible times of year to analyze and that a few old school section drawings might be your simplest tool. Also - assuming you have confirmed that the PV panels/tiles are indeed significantly reflective? I’ve worked on many rooftop PV arrays here in NYC in dense urban surroundings using industry-standard materials from companies like Sunpower, and I don’t recall issues with secondary reflections ever once coming up. Its been a while, but don’t they typically have matte glass surfaces? If you have not already confirmed reflectance maybe check you have an issue at all.

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No, I started reading a book on the subject and there it was said that such cases, where disturbing reflections arise, often lead to disputes and end up in court. Therefore, I preferred to clarify beforehand whether there could theoretically be problems in this regard. I have not yet looked at any concrete modules.

(And even if theoretically there is no problem, practically in SketchUp it is much too tense not to look at it.)

It’s fun to change the time and date and search for the sun in the “mirror” :wink:
(wit interactive Vray viewport render)

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