Mystery solar panels appearing on existing street light poles in Los Angeles

[DanKegel]

Did a double-take today when driving to the drugstore - six lightpoles had sprouted large solar panels.
Here's a couple shots of one (the only one with an equipment box on the pole):

https://goo.gl/photos/M8y1D9H43LecmGGf8

Tomorrow I'll try to get better shots, but to my untrained eye those panels look a lot like these:

https://goo.gl/photos/8qnW48DfDheZpt2L9

Those poles already had power; it's kind of hard to imagine the city turning all its lightposts into a giant distributed solar farm.
I wrote the city's street lighting bureau to see what they're up to.

[SunEagle]

Hmm. Did you by any chance sell them your extra bifacial panels?

[DanKegel]

Ruh-roh, you used the B-word!

[J.P.M.]

Save your time or not as you wish. Or, a 30 sec. search lead me to a co. called "Greenshine". I'm sure there are lots of others. Looks like L.A. street lighting dept. has some of their stuff, maybe on test or as part of a general shift to LED's for street lighting as per their website. Not much new or striking here.

Although I'm still quite skeptical until I see some work and some #'s I can trust, depending on cost and more importantly if considering bifacials, albedo at a location, bifacials may make some sense due to the elevation above the surroundings, but it looks to me that the mounting will need some mods. to address backside blocking.

[DanKegel]

Yeah, I saw Greenshine's site; doesn't look like their stuff.

Those lampposts were converted to LEDs over a year ago, along with most of the rest of the city's. The solar panels appeared in the last month, so this is something new.

Yeah, avoiding self-shading seems like an obvious opportunity for improvement.

[J.P.M.]

Yeah, I saw Greenshine's site; doesn't look like their stuff.

Those lampposts were converted to LEDs over a year ago, along with most of the rest of the city's. The solar panels appeared in the last month, so this is something new.

Yeah, avoiding self-shading seems like an obvious opportunity for improvement.

Like as wrote, maybe part of ongoing testing. Looks a lot like Greenshine's stuff to me. Bu then, they're not the only game in town. Probably lots of others. In any case, not much new/exciting here. As you wrote, conversion was over a year ago.

I suspect most of the long term savings will come from the LED changeout rather than the PV supplement to the power used. Hypsters/con men/shills seem to often have a way of combining savings from conservation and any R.E. contribution in ways that mask R.E.'s sometimes/often lower cost effectiveness vs. simpler and more cost effective conservation measures. Follow the money.

Nothing new here. Overall, IMO, this thread seems another waste of electrons.

[SunEagle]

Ruh-roh, you used the B-word!

Oh. I am still interested in the production ability of the bifacial technology. I just wouldn't think using them on very tall lighting fixture poles would be a smart application.

I like the idea of a white roof or reflective background but I would think the distance between panel and reflective surface would be measured in inches not meters.

[jflorey2]

Did a double-take today when driving to the drugstore - six lightpoles had sprouted large solar panels.

Around here lightpole-mounted solar panels are commonly used to power traffic cameras, weather monitors and wireless signal relays.

[DanKegel]

I suspect most of the long term savings will come from the LED changeout rather than the PV supplement to the power used.

I've seen several kinds of solar street lights in LA; they look like integrated systems.
The panels I noticed yesterday seem very different, as if they just slapped a solar panel on a pole. I doubt they're lighting-related.
Seems more likely the poles are just conveniently located installation points, and the panels serve some other purpose.
But what? Hence the word 'mystery' in the topic title.

BTW I did get a good look with a zoom lens; the panels are type GxB-310.

Suneagle, apropos distance between panel and reflective surface: http://ieeexplore.ieee.org/stamp/sta...number=7387697 found that output increased linearly with height above the ground (at least in the range 0.15 to 0.8 meters).

[SunEagle]

I've seen several kinds of solar street lights in LA; they look like integrated systems.
The panels I noticed yesterday seem very different, as if they just slapped a solar panel on a pole. I doubt they're lighting-related.
Seems more likely the poles are just conveniently located installation points, and the panels serve some other purpose.
But what? Hence the word 'mystery' in the topic title.

BTW I did get a good look with a zoom lens; the panels are type GxB-310.

Suneagle, apropos distance between panel and reflective surface: http://ieeexplore.ieee.org/stamp/sta...number=7387697 found that output increased linearly with height above the ground (at least in the range 0.15 to 0.8 meters).

Actually that makes sense that you would get more light reflected back depending on the height of the panel and how much of surface area that can be focused to reflect light back to the panel.

Sort of like a magnifying glass. As you move it up and down you will see the focus change but at some point you get the smallest spot and hottest focus. So maybe the same with the bifacial panel. Too close and not enough sunlight. Too far and again not enough sunlight is focused, but at 0.8 meters is just right. Or I am just making foolish estimations because I know nothing about the technology.

[DanKegel]

Well, you're still thinking about concentrating light. Bifacial panels don't require concentrated light; you just mount them over a high-albedo (roughly, white) surface.

If you mount them high enough / space them far enough apart that the surface under them is brightly lit by sunlight, some of the diffuse reflection from the brightly lit surface will indirectly illuminate the underside, and you'll get some power off the underside. No focusing involved.
If you mount them flush so no sunlight gets under them, you won't get any power off the backside.

[J.P.M.]

Well, you're still thinking about concentrating light. Bifacial panels don't require concentrated light; you just mount them over a high-albedo (roughly, white) surface.

If you mount them high enough / space them far enough apart that the surface under them is brightly lit by sunlight, some of the diffuse reflection from the brightly lit surface will indirectly illuminate the underside, and you'll get some power off the underside. No focusing involved.
If you mount them flush so no sunlight gets under them, you won't get any power off the backside.

Dan, do you have any idea of how much reflected solar radiation the back side of a panel might receive under various conditions, conceptually what's going on, or how to estimate those numbers ?

I do not believe you do. I think that way because I believe I do, and if you knew some of what I think I might now about it, my opinion is you'd get off the bifacial bandwagon, because you'd see it as a very limited and specialized application. Start by asking yourself 3 common sense, practical questions: 1.) How much solar energy does the backside of a typical roof mounted panel see ? Answer: little to none, probably about something of the order of 1% of the front side. 2.) How many residential PV applications are not parallel to the roof surface ? 3.) For higher tilt angle applications how much of the albedo that is backscattered by the surroundings and does manage to reach the backside of such an array at anything approaching a useable angle ? Answer: not much, maybe of the order of a couple of %.

Bifacials may have some limited application, but it's rather specialized and in any event, you do not have the background to speak knowledgeably about efficacy or limitations of bifacials, so stop misleading folks by treating bifacials as the latest and greatest. The idea has been around for a long time, a lot longer than the 40+ yrs. I've been around, such as for V troth reflectors and dual sided thermal collectors in the early 20th century and commonly found of limited value.

You continue to spread B.S. and tripe, and embarrass yourself. Your ignorance is wasting others' time and probably misleading them. I consider such behavior rude and inconsiderate.

[DanKegel]

1.) How much solar energy does the backside of a typical roof mounted panel see ?

Very little, and that's why bifacial panels are not recommended for that application. Why do you ask?
It's kind of an odd thing for you to bring up, considering that I didn't suggest in this thread that anyone do that.

[SunEagle]

Well, you're still thinking about concentrating light. Bifacial panels don't require concentrated light; you just mount them over a high-albedo (roughly, white) surface.

If you mount them high enough / space them far enough apart that the surface under them is brightly lit by sunlight, some of the diffuse reflection from the brightly lit surface will indirectly illuminate the underside, and you'll get some power off the underside. No focusing involved.
If you mount them flush so no sunlight gets under them, you won't get any power off the backside.

Maybe I used the wrong analogy of the magnifying glass. I am thinking of something like the focal plane in photography, where the correct amount of light is reflected back from one surface to another to generate a clear picture.

If the target surface is too close, not enough light gets reflected back to be turned create a picture or generate electricity. If the target surface is too far again the light is diluted so not enough gets back to produce picture or generate electricity. But at the right distance (whatever that is) you get enough reflected back to produce a clear image for a picture or for the solar panel the anticipate % production output of electricity.

Again this is all in my head

[jflorey2]

If the target surface is too close, not enough light gets reflected back to be turned create a picture or generate electricity. If the target surface is too far again the light is diluted so not enough gets back to produce picture or generate electricity. But at the right distance (whatever that is) you get enough reflected back to produce a clear image for a picture or for the solar panel the anticipate % production output of electricity.

If the area reflecting is large in relation to the area receiving the power, it doesn't matter how far it is. It could be infinitely far away, and as long as it was also infinitely large, you'd get the same amount of power as an infinitely large reflecting plane that was ten meters away.

So if it's over something that's large, like a freeway (and the freeway is doing most of the reflecting) it shouldn't matter. But if it's small, like a section of sidewalk, then it would be important to have it the 'right' distance.