Mirrors to increase the power of solar panels?

ECO20 · 02-21-19, 02:56 PM

Does anyone use mirrors to increase the power of solar panels?

Piwoslaw · 02-22-19, 02:08 PM

You should be careful with mirrors - they can easily "fry" your panels.
PV efficiency lowers with temperature, while solar hot water may boil in the panels if the mirrors add energy faster than the pump can move the water.

elhigh · 03-18-19, 05:09 AM

Not mirrors per se, but my wife recently saw a YouTube video in which the Canadian homeowner stood his ground mount panels straight up in wintertime to take advantage of the strong reflected light from the snow to help compensate for his very northern location.

Bicycle Bob · 03-21-19, 06:53 PM

It is well to get some extra high-temperature resistance in any ancilliary hardware, but the panels themselves are fine with heat, except for the reduced performance. So, output does not go up linearly with extra light unless you can maintain the temperature. This is not usually too difficult, so I'm surprised it was not used more when sun trackers were cheaper relative to panels.
There is one legend about the DOE getting a notion that it might be nice to have some standard component that would produce both heat and electricity. They shopped this idea around to the energy experts, and several oil companies were persuaded to try meeting the specs. After all the budget was allocated, a little company in Boston pointed out that they had been producing such a device for years. It was just a glazed box to collect hot air, but the sun also hit mylar cones surrounding solar cells.

ham789 · 03-21-19, 07:27 PM

Quote:

Originally Posted by ECO20

Does anyone use mirrors to increase the power of solar panels?

There are numerous issues with this.
To name a few...
The output of a panel is related to something like the cosine of
the angle of incidence. As the sun moves the output changes.
You can keep the angle perpendicular with a two-axis sun tracker.

If you try to use mirrors, how are you gonna arrange them?
How are you gonna track the sun? A small change in incident angle
decreases solar output by a small amount. But a change in the angle incident
on the mirror can cause the energy to miss the panel entirely.
Even a partial miss can decrease output dramatically.

Then there's heat. If you've ever tried to start a fire with a magnifying
glass, you have seen the effects of concentration.

Somebody has to keep the mirrors clean.

Mirrors work great when you have a bunch of them actively tracking
and projecting/focusing the energy on a small boiler high in the air.

ldjessee · 03-22-19, 09:19 AM

I saw this video a few days ago, which basically agrees with what is said by others. Not really worth it.

YouTube video on using mirrors with solar PV panels.

Piwoslaw · 01-02-21, 12:23 PM

I've been thinking about this: The main problem with increasing PV output with mirrors is the penalty of additional heat.
I'm no expert, but PVs only convert certain wavelengths of light into electricity, and infrared (=heat) is not one of them.

Also, each materials reflects certain wavelengths better than others.

So, are there "mirrors" which reflect visible light but not heat? What materials could be used for this?

SDMCF · 01-03-21, 03:17 AM

Quote:

Originally Posted by elhigh

Not mirrors per se, but my wife recently saw a YouTube video in which the Canadian homeowner stood his ground mount panels straight up in wintertime to take advantage of the strong reflected light from the snow to help compensate for his very northern location.

My evacuated tubes are mounted almost vertically on the south-facing wall of my home. At our lattitude the winter sun is low on the horizon. The ground slopes away from the house towards the south and in winter it is covered with snow. I believe the light reflected by the snow is one reason that the most productive months for my system are February & March, even though temperatures can be below -20F.

holbrookged · 08-03-21, 02:12 PM

I'm strugglign to see how you could position mirrors to reflect onto panels that are on a roof facing upwards?

SDMCF · 08-04-21, 08:27 AM

At my lattitude the winter sun is barely over the southern horizon. To be at 90 degrees to the incoming sunlight my panels are mounted almost vertical on my south-facing wall. The ground slopes away from my south-facing wall. So the sun hits the slope to the south of my house and is reflected up onto my solar panels (tubes).

In a location where panels have to be mounted on the roof it would be much more difficult to refect additional light onto them.

02-21-19, 02:56 PM	#1
ECO20 Lurking Renovator Join Date: Feb 2019 Location: NY Posts: 5 Thanks: 1 Thanked 1 Time in 1 Post	Mirrors to increase the power of solar panels? Does anyone use mirrors to increase the power of solar panels?

02-22-19, 02:08 PM	#2
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 964 Thanks: 189 Thanked 111 Times in 87 Posts	You should be careful with mirrors - they can easily "fry" your panels. PV efficiency lowers with temperature, while solar hot water may boil in the panels if the mirrors add energy faster than the pump can move the water. __________________ Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.

01-02-21, 12:23 PM	#7
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 964 Thanks: 189 Thanked 111 Times in 87 Posts	I've been thinking about this: The main problem with increasing PV output with mirrors is the penalty of additional heat. I'm no expert, but PVs only convert certain wavelengths of light into electricity, and infrared (=heat) is not one of them. Also, each materials reflects certain wavelengths better than others. So, are there "mirrors" which reflect visible light but not heat? What materials could be used for this? __________________ Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.

08-03-21, 02:12 PM	#9
holbrookged Lurking Renovator Join Date: Aug 2021 Location: Allestree Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	I'm strugglign to see how you could position mirrors to reflect onto panels that are on a roof facing upwards? __________________ Sorry, new users are not permitted to post links in their signatures.

03-18-19, 05:09 AM	#3
elhigh Helper EcoRenovator Join Date: Jan 2013 Location: Tennessee Posts: 41 Thanks: 3 Thanked 5 Times in 4 Posts	Not mirrors per se, but my wife recently saw a YouTube video in which the Canadian homeowner stood his ground mount panels straight up in wintertime to take advantage of the strong reflected light from the snow to help compensate for his very northern location.

03-21-19, 06:53 PM	#4
Bicycle Bob Suncatcher Join Date: Sep 2008 Location: Spiritwood, Northern Saskatchewan Posts: 42 Thanks: 0 Thanked 1 Time in 1 Post	It is well to get some extra high-temperature resistance in any ancilliary hardware, but the panels themselves are fine with heat, except for the reduced performance. So, output does not go up linearly with extra light unless you can maintain the temperature. This is not usually too difficult, so I'm surprised it was not used more when sun trackers were cheaper relative to panels. There is one legend about the DOE getting a notion that it might be nice to have some standard component that would produce both heat and electricity. They shopped this idea around to the energy experts, and several oil companies were persuaded to try meeting the specs. After all the budget was allocated, a little company in Boston pointed out that they had been producing such a device for years. It was just a glazed box to collect hot air, but the sun also hit mylar cones surrounding solar cells.

08-04-21, 08:27 AM	#10
SDMCF Apprentice EcoRenovator Join Date: Jul 2014 Location: Finland Posts: 125 Thanks: 5 Thanked 35 Times in 34 Posts	At my lattitude the winter sun is barely over the southern horizon. To be at 90 degrees to the incoming sunlight my panels are mounted almost vertical on my south-facing wall. The ground slopes away from my south-facing wall. So the sun hits the slope to the south of my house and is reflected up onto my solar panels (tubes). In a location where panels have to be mounted on the roof it would be much more difficult to refect additional light onto them.