| Tubular Solar Panels Slash Costs, Boost Efficiency |
| Written by Hank Green | ||
| Tuesday, 07 October 2008 | ||
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First, as to the second point, when dealing with thin-film CIGS solar panels, cylindrical is just as good as flat. But the first point, concerning harvesting the maximum amount of sunlight, gets a little confusing. The cylindrical solar panels (think of fluorescent tube lights...except in reverse) can absorb energy from every direction, and when combined with a white roof (which are now the only legal, flat roofs in California) can capture up to 20% more light than traditional solar panels. The other gigantic advantage is that they don't have to move to track the sun. The panels are always presenting some of their face directly perpendicular to the sun. By removing solar-tracking and orientation from the equation, these systems can simply be laid onto roofs. Tracking solar panels have to be able to resist the force of strong winds, these will just lay flat and out of the way reducing installation costs, which often comprise about half of the price of a solar project. And with 30 billion square feet of flat roofs in America, this could be quite a market for cheap, clean electricity. Solyndra just announced, in fact, that they've got $1.2 B in contracts throughout Europe and America, and I can't imagine that going anywhere but up. Full press release from Solyndra below SOLYNDRA RESHAPES SOLAR PANELS FOR COMMERCIAL ROOFTOPS
Proprietary panels designed to provide higher electricity output per rooftop and significantly reduced installation costs
Company announces more than $1.2 billion in customer contracts
FREMONT, Calif., October 7, 2008 – Solyndra, Inc. today announced a new solar photovoltaic (PV) system for the commercial rooftop market. Solyndra’s PV system is designed to generate significantly more solar electricity on an annual basis from typical low-slope commercial rooftops with lower installation costs than conventional flat panel PV technologies. Commercial rooftops represent a vast, underutilized resource and huge opportunity for generating solar electricity. Since its founding in 2005, Solyndra has been developing technology and ramping manufacturing capacity to produce its proprietary CIGS-based thin film PV system. Solyndra is currently shipping its systems, comprised of panels and mounting hardware, to fulfill more than $1.2 billion of multi-year contracts with customers in Europe and the United States.
The New Shape of Solar Solyndra’s panels employ cylindrical modules which capture sunlight across a 360-degree photovoltaic surface capable of converting direct, diffuse and reflected sunlight into electricity. This self-tracking design allows Solyndra's PV systems to capture significantly more sunlight than traditional flat-surfaced solar panels. Traditional PV systems require costly tilted mounting devices to improve the capture of direct light, offer poor collection of diffuse light and fail to collect reflected light from rooftops or other installation surfaces.
Additionally, conventional flat PV panels must be mounted at an angle and spaced apart for optimum energy production, resulting in sunlight being wasted by striking unutilized portions of the roof. Solyndra’s panels perform optimally when the panels are mounted horizontally and packed closely together, covering significantly more of the available roof area and producing more electricity per rooftop on an annual basis than a conventional panel installation.
Cost-Effective Installation To meet rooftop wind loading requirements, conventional flat solar panels must be anchored to commercial roofs with either ballast or rooftop penetrations, which are inherently problematic. Together with the need for tilting, the resulting complex mounting systems require significant investment in labor, materials and engineering resources. Conversely, because wind blows through Solyndra panels, no rooftop anchoring is required. Further, the low weight of the Solyndra system enables the installation of PV on a broader range of rooftops.
For typical conventional PV installations, a solar panel is only half the cost of a complete installation; the other half includes additional expenses such as installation, cables and inverters. The horizontal mounting and unique air-flow properties of Solyndra's solar panel design substantially simplify the installation process for Solyndra's PV systems. The ease of installation and simpler mounting hardware of Solyndra's system enables its customers to realize significant savings on installation costs.
“By eliminating the need for roof-penetrating mounts and wind ballasts, PV arrays with Solyndra panels can be installed with one-third the labor, in one-third of the time, at one-half the cost,” said Manfred Bachler, chief technical officer at Phoenix Solar AG, one of the largest solar power integrators in Europe and a Solyndra customer. “For commercial rooftops, PV module installation time can now be measured in days, not weeks. For flat commercial rooftops this is game-changing technology.”
According to Solyndra founder and CEO Chris Gronet, "Solyndra’s system uniquely optimizes PV performance on commercial rooftops by converting more of the sunlight that strikes the total rooftop area into electricity while also providing for a lower installation cost and lower cost of electricity.”
About Solyndra
Comments
(8)
Round, huh? Cool!
written by Steve N. Lee , October 07, 2008
Cylinder Costs
written by Carl , October 08, 2008
Interesting that apparently it's cheap enough to coat 360 degrees of the tube vs the 1/3 less length of a flat plate. With all these new technologies and startups, I think it's really going to come down to the cost of mounting and installation. So adding extra thin film might be cheaper per install, hence total $.
Hmmm, since there is a tube, why not run water (or air) through it? Heat is a problem for solar panels-- they lose efficiency when warm. Cooling the solar tubes could be used for winter building heat, pre-warming hot water, or pool heating. It seems like the same principle (partly) could be applied to flat strips, e.g. a M shape, or just a coated L bracket (inverted V). It would be structurally secure, and capture more of the morning and afternoon sun per roof area, at the cost of a little greater panel surface area.
Software Director
written by Daniel , October 08, 2008
I'm a little skeptical about this - I've never worked with CIGS solar cells, but I built a solar car using standard silicon cells. My recollection was that a solar cell is just a reverse biased diode. When it's not pumping electrons against the bias, it blocks electrons from flowing. That meant that if a cell is partially shaded, it quickly gives up all of its power production, and also saps power from cells that it is serially wired to.
How can a curved cell, which is always partially shaded, and certainly illuminated non-uniformly, work at all? Also, how could it be more efficient than a continuous panel when it appears to capture light on about 50% of it's frame area? I suspect it is more efficient than a solar panel with the same cross sectional area. Picking up reflected light will be substantially less efficient than capturing it on the way down. It sounds to me like they are putting in about pi times as much solar cell area as a flat panel, and the main advantage is that it is more wind resistant. I'm not saying it's worthless, but I'm not convinced the yield from a rooftop will be competitive with standard flat cells (CIGS or otherwise).
@Carl
written by James , October 13, 2008
Carl,
Looking at Solyndra's website, the tubes are hermetically sealed because moisture can drastically degrade the lifetime of the CIGS material. I think it would be very difficult to assemble a tube that is hermetically sealed around the CIGS part, yet has an open path through the middle to allow for heating water or air. Probably not cost efficient!
self cleaning
written by ross harrison , October 14, 2008
dose any one know if these solar tubes have a coating of titanium dioxide on the outside so that they are self-cleaning I know this would stop the tubes from absorbing UV light but im not sure on the spectrum they convert, if they don’t convert UV would this be a very good idea?
If anyone knows what spectrum they convert can you let me know pleas. Thank you Ross
Same principle as heatpipes
written by frisbee , October 16, 2008
The idea of round tubes to collect solarheat (in stead of PV) is being used very succesfully in vacuum heatpipes.
I guess for the PV version to realy be efficient depends on the abbility of the system to 'lock up' cells that become shaded, in order to prevent them from sucking up the production of unshaded cells. Does anyone know if Solyndra has anything doen about this? Cooling this system by absorbing the waste heat might be done in combination with vacuum heatpipe collectors on the inside, though I wonder if the amount of waste heat produces by the PV's would be enough to make that economicaly viable....
not entirely accurate
written by bWs , October 16, 2008
The fact that these are round tubes and so present a perpendicular surface to the sun regardless of time of day is somewhat misleading. The sun also moves north and south throughout the year, so the tubes, unless tracking this n/s movement, are perpendicular only twice each year (much the same as a broken clock shows the correct time twice a day).
...
written by Total Solar Energy , November 06, 2008
i've already checked out this company. i looked into buying shares in them. as far as i'm aware they are not on the stock market. this has the potential to do great things for the industry. their product seems such basic common sense. why didn't i think of it?....
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There are a lot of reasons to think that flat solar panels would be the right way to go. The best way to capture sunlight is by being perpendicular to the sun and it's usually cheaper to make things flat than round. But the folks at 
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But this is great. Cheaper to install AND 20% more efficient? Fantastic. But it gets better. Better in a way that Hank hasn't addressed. Because these are so much more efficient and so much cheaper to install, not to mention cheaper to maintain, it will make solar viable in areas that it hasn't been up to now.
Cost has always been the prohibitive factor - as with most things in life - so areas that didn't get an optimal number of sun-hours meant solar was simply dismissed. Now that scenario will change dramatically. I'm sure there'll have been research done on this, to see how many more areas this kind of solar could be be viable, which would be very interesting reading.
And, of course, with the tax credits system no in place, this is a wonderful time for expansion and innovation in solar. Let's hope people see the advantages of this technology and embrace it wholeheartedly.
Steve N. Lee
author of eco-blog http://www.lionsledbysheep.com
and suspense thriller 'What if...?'