Hyper X panels

[J.P.M.]

My first solar panels were Arco Tri-Lams which where used in a somewhat similar setup. Rather than two "suns" worth of power, they had mirrors on both sides to direct additional sun onto the panels. This increased their output to about two and a half times normal. I got them for very cheap ($5/watt which at that time was half the retail price) because they had all turned brown from overheating.

Doing a heat (energy) balance on a panel will probably show that the side booster mirrors will also increase the panel temp. to a very high level. All that extra irradiation not turned into electricity need to be dissipated. that will require increased panel temps. ass described. concentration of irradiance needs external cooling considerations at fairly low concentration ratios, and in any case, will increase maint. and shorten service life. Sounds like Arco may have dropped the design ball on that one.

[jflorey2]

I wonder if using the same "simulated sun" light source aimed at both sides of a panel mounted vertically would produce double the "front" side production?

My first solar panels were Arco Tri-Lams which where used in a somewhat similar setup. Rather than two "suns" worth of power, they had mirrors on both sides to direct additional sun onto the panels. This increased their output to about two and a half times normal. I got them for very cheap ($5/watt which at that time was half the retail price) because they had all turned brown from overheating.

[SunEagle]

Efficiency on the back side is... is... isn't specified on the data sheet,

http://www.sunpreme.com/wp-content/uploads/2015/04/Sunpreme-Datasheet-GxB-300W-Bifacial-Module-Rev-1.3.pdf

Maybe I should mount one of mine upside down

That would be interesting to see if the back side is as efficient (20%) as claimed. But if you think about it, the "front" and "back" should be the same if exposed directly at the sun. The "back" gets up to 20% more production from reflected light off the roof surface which is then added to the "front" production to increase the overall % production.

I wonder if using the same "simulated sun" light source aimed at both sides of a panel mounted vertically would produce double the "front" side production?

[inetdog]

Mirrors, we use the snow that way when its here. But effective mirrors would be as big
as the panels, more mounts, and honestly cleaning them could be a monumental
problem relative to the additional generation. Bruce Roe

Actually a lot bigger than the panels unless you put tracking on the mirrors too.
An interesting question is whether the added current is effectively in parallel with the front-side current.
If you have partial shading (actually partial un-mirroring?) on the back side do you have the same problem as for the front, namely that weakest cell limits the current for each bypass group? Presumably yes.

[DanKegel]

Seems like, bifacial panels ought to be good for a setup like mine. Catching the rising
and setting sun. But if the sensitivity is only a fraction on the back side...

Efficiency on the back side is... is... isn't specified on the data sheet,

http://www.sunpreme.com/wp-content/uploads/2015/04/Sunpreme-Datasheet-GxB-300W-Bifacial-Module-Rev-1.3.pdf

Maybe I should mount one of mine upside down

[bcroe]

Do any of you guy's/gal's have tracking on your systems? if so why?

I am looking at being able to easily tilt panels. For winter, vertical will pick up a lot less
snow and also do better with sun reflected off the snow. If it works well, might consider
trying to use it over the day.

Trying to track with a 2 axis or equatorial mount made some sense when panels were
super expensive. It gets to be quite a project if you have lots of todays cheap panels.
The only way I see to turn a 20 KW array is put it on a barge in a big pond. A bunch
of smaller units require a lot of space to avoid getting in each others shadow.

Its so much easier now to just use more panels, perhaps facing multiple directions. And
in these parts we have lots of clouds. A tracker will do nothing to compensate for clouds.
But when clouds disperse the light, ALL the panels in a multi orientation array will supply
power, if somewhat reduced.

Seems like, bifacial panels ought to be good for a setup like mine. Catching the rising
and setting sun. But if the sensitivity is only a fraction on the back side, I'd have to
alternate the front & back strings, to balance them, and the support structure would
approach twice as big.

Mirrors, we use the snow that way when its here. But effective mirrors would be as big
as the panels, more mounts, and honestly cleaning them could be a monumental
problem relative to the additional generation. Bruce Roe

[glennestanford]

question?

A roll of Tyvec might be cheaper and more effective to put under bifacials.
But even that might not be cost effective, and might not weather well or look good.

I hope to have some data on that from my own installation someday.

If you feel like experimenting, have at it, the bifacial panels are on the market.

Do any of you guy's/gal's have tracking on your systems? if so why?

[DanKegel]

You can purchase ceiling grid at HD, Lowes ect. There are lay in panels that have a reflective face on them that looks just like a mirror, they are mostly used in commercial/retail building/stores to simulate that there are security camera's behind them, ...

A roll of Tyvec might be cheaper and more effective to put under bifacials.
But even that might not be cost effective, and might not weather well or look good.

I hope to have some data on that from my own installation someday.

If you feel like experimenting, have at it, the bifacial panels are on the market.

[sensij]

I am beginning to believe I am not welcome in this group of experts that have made their fortunes by dealing in PV

I don't think you understand this group very well. So far all you've presented are a bunch of sales-pitch ideas of what bi-facials *could* do. When you look at the costs of installing bifacials in a manner that maximizes the backside response, the net cost is likely to be greater per kWh generated than just using standard panels in a conventional installation. If you want to sell these panels as a way to maximize production, cost be damned, that is a more nuanced position that would be easier to defend. There aren't too many "cost be damned" installations going up around here, though.

DanKegel linked a nice design guide for installing bi-facials. Whether or not those calculations hold up in the real world is unknown, but at least there is some engineering logic to what they outline. If you described your intended installation in the context of those guidelines, you might get more encouragement than what you've found with the "the sales guy told me they've sold lots of panels, so they must be good" argument.

You say that if the panels didn't perform as you think, there would be knowledge of that "in the public". Guess what, you are talking to the "public" here, and not finding anyone to confirm the boost in power. Those panels have been on the market for years, don't you think there would be more companies making them if they were truly as revolutionary as you believe them to be?

[jflorey2]

times and technology do change and why not try to take advantage of it, just like going from a 45 record to CD players .. . .

But per your rationale, if the 45 record was more energy efficient, you'd have to stick with that - because why not make the most of the energy you have, instead of just "add more power?"

[glennestanford]

No, it's simple...

It's complicated.

According to Sunpreme, yes you can use just white paint under the panels for a gain in harvest, now how much ? I don't know, but if its there I want to get it, To hell with the just add more panels mentality, I look at this the same way as gas mileage in a car, why not get the most mileage you can out of it if it's available instead of , Just add more gas. I suggest you or anyone that is interested in this contact the company and ask questions just as I did. I am beginning to believe I am not welcome in this group of experts that have made their fortunes by dealing in PV, Almost every comment I have made is met with arrogant, smart a** response, They claim they have sold thousands with great success, and yes its like a used car salesman, they may tell you what you want to hear, but if they have that many in the field that has problems I feel sure it would be out in public by now. times and technology do change and why not try to take advantage of it, just like going from a 45 record to CD players, or are you still watching analog black and white TV, AM radio, no AC in your car or house (unless you are in the right climate) or Heart bypass surgery, ect. you get my drift.

[glennestanford]

reflective material

So, to confuse things more - what are we talking about when we say 'reflective material'? I"m sure ther emust be some high-end specific materials that actually do reflect light well, but what about more mundane options?

• A TPO roof with raised racking for the mods?
• An empty "foyer" with the panels 30' above it?
• painting bricks on nearby walls (of that foyer, for example) white?
• is white paint really enough, or is that just bad science?
• Is a standard metal roof shiny enough, assuming we could get above it far enough for effectiveness?

Thanks. I've never really run the numbers on this. I've installed Solyndra on TPO and that foyer rack - I call it that, but it was more like a wide patio cover, maybe 60' across, between two buildings that had the same height).

I'm I'll read trough that bifacial design guide that was posted earlier, but I'm still curious what kind of light augmentation we're really working with here.

You can purchase ceiling grid at HD, Lowes ect. There are lay in panels that have a reflective face on them that looks just like a mirror, they are mostly used in commercial/retail building/stores to simulate that there are security camera's behind them, but they are not transparent, just made with a reflection on one side. I don't know if HD, Lowes handle them, but you can get them at supply houses that sell ceiling construction related materials. I had a HVAC/Electrical, maintenance/repair/replace contract for a chain of Shoe stores that had them in ever store that I ever went to, and that was over 100. I will check and see what the price is, installing ceiling grid is simple and easy, just use these panels instead of typical ceiling tiles. 100% light reflection, or the same as a mirror. Actually upon checking on prices it will range from $1.65 and up per sq ft, it would be more cost effective to use treated 1/2" plywood with wall mirrored type non glass tiles.

[J.P.M.]

So, to confuse things more - what are we talking about when we say 'reflective material'? I"m sure ther emust be some high-end specific materials that actually do reflect light well, but what about more mundane options?

• A TPO roof with raised racking for the mods?
• An empty "foyer" with the panels 30' above it?
• painting bricks on nearby walls (of that foyer, for example) white?
• is white paint really enough, or is that just bad science?
• Is a standard metal roof shiny enough, assuming we could get above it far enough for effectiveness?

Thanks. I've never really run the numbers on this. I've installed Solyndra on TPO and that foyer rack - I call it that, but it was more like a wide patio cover, maybe 60' across, between two buildings that had the same height).

I'm I'll read trough that bifacial design guide that was posted earlier, but I'm still curious what kind of light augmentation we're really working with here.

It's complicated.

[Rocksteady2R]

So, to confuse things more - what are we talking about when we say 'reflective material'? I"m sure ther emust be some high-end specific materials that actually do reflect light well, but what about more mundane options?

• A TPO roof with raised racking for the mods?
• An empty "foyer" with the panels 30' above it?
• painting bricks on nearby walls (of that foyer, for example) white?
• is white paint really enough, or is that just bad science?
• Is a standard metal roof shiny enough, assuming we could get above it far enough for effectiveness?

Thanks. I've never really run the numbers on this. I've installed Solyndra on TPO and that foyer rack - I call it that, but it was more like a wide patio cover, maybe 60' across, between two buildings that had the same height).

I'm I'll read trough that bifacial design guide that was posted earlier, but I'm still curious what kind of light augmentation we're really working with here.

[J.P.M.]

Thanks, Some very good info, looks very promising to me, enough so if I could afford a system I would definitely add a reflective material, why invest 20k in a system and not do it for more energy for the life of the system or reflective system when you could invest most likely less that 1k for a system for 1/4 or more energy? I would build a passive tracker and attach the reflective system rigid below it to have reflection all day, with 4 season manual adjustment.

The time I spent ~ 40 yrs. ago studying the geometry, usefulness and limitations of utilizing reflectors for irradiance augmentation paid dividends in the way I thought about solar geometry and the solar resource, and also led me to the reality of the practical futility of the enterprise for anything other than hi tech, commercial or hi risk ventures of the pie in the sky variety.

Residential and small scale solar is low tech, almost by definition and need. Reflectors, while they seem like a no brainer, complicate things in ways greater than the slight and usually poorly understood ways they may improve theoretical performance. Basically, they ain't worth it.

Similar to those who have little understanding of design for wind, seismic or other occasional external loadings, the cost of adding reflectors in terms of engineering, time and materials is greater than most people understand. Or even imagine.

A fascinating subject that unfortunately seems to attract an unusually large %age of "you could just" types who have not yet grasped the science and technology of the subject to understand the real and practical limitations. Or, cheap SOB's like me who had not yet discovered you can't cheat entropy.

BTW: And not to rain on your parade, see what's available before you design a passive tracker. Lots of designs already around, but good luck. Along the way, I built a semi passive tracker in the '80's using a Wheatstone bridge, a gimbal support, a few silicon cells, some shading material, a couple of early versions of step motors and some parts on a breadboard. Proof of concept stuff. Long story. It worked OK but wasn't real precise, mostly due (as I remember) to the motors. I felt real good about it until I found out someone had done something essentially identical way before me. The enthusiasm of youth meets the reality of nothing new under the sun.

Take what you want of the above. Scrap the rest.