Solar Panel Glare

[Skotty]

A seemingly rising and potentially reasonable concern for rooftop and ground mount solar installations is sun glare that can shine on neighbor houses and be a nuisance. I saw a TV report on one case like this, and it's a concern among some members of my HOA. My wife and I think it's a potentially reasonable concern.

This is going to be possibly a bigger issue for ground mount, and less an issue for rooftop solar. But it could still be an issue even with rooftop.

My wife and I are attempting to do a glare study by accurately modeling our roof and neighboring houses and analyzing reflections from the rooftop over the range of sun elevation between winter and summer north to south and throughout the day east to west. We hope from this we can determine which parts of the roof, if any, will cause glare issues on neighboring houses, and then avoid installing panels on those spots. The model we are using is a physical scale model of the neighborhood and roof, using the highest accuracy we can. Sun angle information I obtained from an online sun earth tools website that seemed reputable.

We thought about doing calculations by hand, or trying to do a computer simulation of some sort, but I think the physical model will provide better visualization and be more consumable by the HOA in our solar proposal.

We have potential roof area on the east, west, and south facing sides of the roof. I'm pretty sure there will be no problem with the south facing roof, but I'm not so sure about the east and west roofs.

I'm curious if any of you have looked into this problem before installing solar, or if you have installers who analyzed this before doing an installation. If so, how was it done?

 

[bkp_duke]

New install here, SunPower black panels. These are "matte" and have less glare then the ceramic roof tiles they are install on.

 

[nwdiver]

A seemingly rising and potentially reasonable concern for rooftop and ground mount solar installations is sun glare that can shine on neighbor houses and be a nuisance. I saw a TV report on one case like this, and it's a concern among some members of my HOA. My wife and I think it's a potentially reasonable concern.

Not saying it's a complete non-issue... but remind anyone concerned that solar panels are designed to ABSORB light.

 

[SageBrush]

My panel specs report glare as a percentage. You could probably find some cheap material with similar reflection and put it up for a test.

 

[dgpcolorado]

My sister had that problem with her DIY fixed ground mount array, in central Oregon, at certain times of the year. She planted some bushes to screen the neighbor's window. Not a problem where I live since I am in a forest with neighbors far away.

Even panels with matte finish glass will get a lot of reflection when the sun hits them at low angles, although it varies with the season. It is a valid concern.

In Colorado HOAs can't prohibit solar panels (state law) but our ACC here does try to consider visual impact and reflection when advising on locating panels.

 

[FredTMC]

I'm concerned about glare. Since tesla isn't saying much about the tile glare I'm assuming it's not great

 

[Merrill]

I have 27 sunpower panels and frankly do not see much glare.

 

[Skotty]

I finished my own personal glare study and will incorporate my findings into the final design.

Part of my analysis was done using a scale model of the roof with a sun simulation rig to get a real visualization of where glare could be a problem. This worked okay. The metal bar on the sun rig can rotate (day to night) and tilt back (winter/summer sun elevation). Not a perfect representation, but good enough. Sun elevation information taken from Calculation of sun’s position in the sky for each location on the earth at any time of day. The one issue that I didn't immediately think about with a scale model was how to simulate the sunlight over the entire scale roof with parallel light beams. Lucky for me, I had a couple of fresnel lens in the basement from a DIY projector project that I was able to use in combination with a bright flashlight with the reflector removed. This worked reasonably well, but was a bit clunky to deal with (had to use combination of clamps to hold fresnel lens which made it a bit too heavy and clunky). Neighboring houses were roughly mapped around the room for the simulation, though I didn't actually build models for the neighbor houses.

I suspect this is more trouble than most people would go to for this. But it more or less worked and I can include the results in the proposal to the HOA (some HOA members were concerned about glare).

What I learned from it is that there are 2 areas that can be an issue, the panels on the East roof closest to the front and the panels on the West roof at the back. I can probably just not install panels in those areas.

You can't quite see it in the picture, but the bare areas are not viable due to dormers or other things that would prevent solar panels from being installed. I didn't model the entire house precisely, just the primary roof spaces where solar panels could be. The roof is 1:39 scale and was built using measurements from within the attic and then cross checked against aerial photography.

Note that this is more panels than the final design will likely have. I put them everywhere possible, including too close to the edges, as this was an analysis of possible glare issues without having any particular set layout. Final design will have fewer panels. Drawn sizes and lines on the panels are to proper scale.

 

[Racerx22b]

Here was my process.

Get quotes from 5 vendors.

Make the best decision based on gut feeling, experience, reviews, and price in no particular order.

Place deposit and wait for install to complete.

Glare concerns.... ZERO

Neighbors do all kinds of crazy crap with zero consideration for their fellow neighbors. Not saying 2 wrongs make a right but if there is glare oh well.

I applaud your dedication and consideration but making a scale model and doing your own glare study seems way more than what anyone would expect you to do. I hope your neighbors are half as considerate towards you as are towards them.