Hyper X panels

[glennestanford]

Has anyone had/have any experience with the Sunpreme bifacial frameless panels and the Solar edge inverter? If what I read is correct, that is the way to go, you can install reflective material underneath and increase harvest by 22% or more! And the Solar edge inverter is the highest rated on the market and will help increase harvest over Enphase Microinverters. Someone please wake me up and bring me back into the world....

[sensij]

Has anyone had/have any experience with the Sunpreme bifacial frameless panels and the Solar edge inverter? If what I read is correct, that is the way to go, you can install reflective material underneath and increase harvest by 22% or more! And the Solar edge inverter is the highest rated on the market and will help increase harvest over Enphase Microinverters. Someone please wake me up and bring me back into the world....

There have been a few threads this year where these have been discussed. Increasing harvest is possible, but your array needs to be designed for it. Simply putting a reflective surface under a flush mounted array won't get you 22%. DanKegel is actually installing these as a test soon, so we'll have some real-world data to look at.

I am unaware of how SolarEdge would consistently outproduce Enphase. Installations can be set up to slightly favor one or the other, but fundamentally, the key to both relative to a string inverter is individual panel MPPT.

[DanKegel]

I doubt very much that adding a white layer underneath flush mounted bifacial panels will provide a worthwhile boost.

That claimed 20% booat is only possible if mounted so their back sides can see some sky or at least well-lit snow.

See

http://kegel.com/energy/solar/retrofit2/

[Rocksteady2R]

SensiJ, wouldn't the SolarEdge 135% allowable DC/AC ratio mean that the solaredge could do more with the reflected light? As I ask that, i think that both systems would be maxed out on that anways... you'd actually have to design to a smaller power ratio because you know that "surplus" is coming.

Which brings up the follow-through - Are those panels rated to include that back side reflective quality, or are they rated top-side only?

Anyone have thoughts?

[DanKegel]

Here's the datasheet for their 60 cell panel:

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

As you can see, it is primarily rated for zero backside boost,
but also includes some data for 10% and 20% backside boost.
But it also cautions that flush mounted panels will see little to no backside boost.

[sensij]

SensiJ, wouldn't the SolarEdge 135% allowable DC/AC ratio mean that the solaredge could do more with the reflected light? As I ask that, i think that both systems would be maxed out on that anways... you'd actually have to design to a smaller power ratio because you know that "surplus" is coming.

The DC-AC size ratio SolarEdge is generally the same as any other inverter. You can put more DC on the inverter, but it doesn't mean you'll increase your peak AC output. Increasing the DC will proportionally increase the output for all times in which the peak output limit of the inverter is not being reached.

I'm not sure you'd have to design to a smaller power ratio though... it kind of depends on how you are using the backside. If it is to pick up extra light in either the morning or evening on an E or W facing array, it probably won't make much difference. If it is a south facing array with some structural reflection to pick up light from the north side, maybe it would matter more.

[glennestanford]

Reflection

What my intentions would be is to install a reflective/mirrored material underneath the array, oversizing a small amount in all directions. That should reflect the same amount of light that passes through the panels, therefore the maximum of the engineered capacity from the backside would be achieved. This install could/would work on any type install, but better efficiencies/consumption will be acquired with the reflective material below the panel at least 2 feet allowing for degree variations perpendicular to the direct sunlight, meaning a ground mount system would allow the opportunity to gather more light to reflect or a system standing off a roof as opposed to a close install. I would like to try a walk under array system with suspended grid ceiling system like in 99% of commercial/retail buildings with mirrored lay in 2x4 tiles.That would in my belief give you as much pass through light as can be reflected by this design. Otherwise the only other way I can imagine to add that much light would be a array high off the ground with reflective array out away from panel array to reflect direct sunlight to the underside of the panel array, this reflective array would have to follow the sun as well as the panel array itself. Or one could install LED lights underneath the panel array to boost light output, at the risk of losing what you have just gained.

[DanKegel]

Or one could install LED lights underneath the panel array to boost light output, at the risk of losing what you have just gained.

Careful there, that sounds rather perpetual-motiony.

You might be interested in http://www.prismsolar.com/pdf/Design_guide.pdf, which gives some tips on predicting the backside boost when e.g. mounted above concrete (a fairly reflective substance).

[J.P.M.]

What my intentions would be is to install a reflective/mirrored material underneath the array, oversizing a small amount in all directions. That should reflect the same amount of light that passes through the panels, therefore the maximum of the engineered capacity from the backside would be achieved. This install could/would work on any type install, but better efficiencies/consumption will be acquired with the reflective material below the panel at least 2 feet allowing for degree variations perpendicular to the direct sunlight, meaning a ground mount system would allow the opportunity to gather more light to reflect or a system standing off a roof as opposed to a close install. I would like to try a walk under array system with suspended grid ceiling system like in 99% of commercial/retail buildings with mirrored lay in 2x4 tiles.That would in my belief give you as much pass through light as can be reflected by this design. Otherwise the only other way I can imagine to add that much light would be a array high off the ground with reflective array out away from panel array to reflect direct sunlight to the underside of the panel array, this reflective array would have to follow the sun as well as the panel array itself. Or one could install LED lights underneath the panel array to boost light output, at the risk of losing what you have just gained.

The cost and complexity of what you describe with reflective surfaces make it impractical and cost ineffective by any means I can imagine. The LED thing is a non starter.

[glennestanford]

Careful there, that sounds rather perpetual-motiony.

You might be interested in http://www.prismsolar.com/pdf/Design_guide.pdf, which gives some tips on predicting the backside boost when e.g. mounted above concrete (a fairly reflective substance).

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.

[sensij]

Good luck. Please consider taking pictures and collecting data, and posting an update to let us know how it goes.

[DanKegel]

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 dunno, "1/4 or more energy" might be overstating it.

It all comes down to cost. A small change in cost of non-bifacial panels vs. bifacial panels could tilt the decision.

[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.

[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.]

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.