A Thin-Film Solar Panel Installation
Many people envision solar power as rigid silicon panels mounted on a roof. With thin film solar cells, you’re more likely to not see them, or even know they’re there. This article is about a real-life thin film solar project.
Not many bloggers are able to witness the technologies we research and write about. It’s one thing to be able to buy afford a cool “green” gadget (usually not very green), but another to see the many forms of solar, wind, geothermal, etc., which are always changing and developing around the world. So when my employer decided to go solar, you might imagine my excitement.
At the moment I work for Magco Inc., a Tecta America company. Tecta is a national commercial roofing corporation that can install green roofs, solar lighting, and solar panels alongside a variety of traditional roofing systems. This solar project is pretty straight forward: our building has a big, flat roof on top of a hill without any shade. You’d have trouble finding a sunnier spot for solar panels.
I was double delighted when I heard that they ordered thin-film solar! Naturally inquiring minds wanted to know: why and what kind?
Magco bought their solar from Uni-Solar, which produces triple-junction laminate panels. That means they laminate the photovoltaic chemicals onto a thin sheet of metal in three layers; each layer reacts to a different range of light. They also laminate a sealant on the panel to protect it from the elements. The benefit of this system is that it reacts better to low or indirect light. Think cloudy days and the hours around dusk and dawn, a. Uni-Solar’s panels operate around 12% efficiency, but they claim to out-perform other forms of PV solar in indirect light, which means they could produce more electricity in certain real-world conditions (cloudy days). The laminate production method also decreases cost because expensive silicon and mounting racks are not required.
In fact, these thin-film solar panels are glued straight onto the roof. (See picture.)
Magco chose these panels for another important reason: no roof penetrations. If you mount racks on your roof, you have to fasten them down. That means punching holes in the roof, which can void your warranty and even damage your roof if it’s not done right. Some solar systems, even silicon panels, have found ways to avoid these problems, and anyone looking into solar should ask about the integrity of their existing roof. Another bonus for Magco and thin-film solar was weight: these solar panels roll out like carpet and don’t weigh as much as silicon. That means Magco wouldn’t need to add any structural support. It does snow here, so weight is an important factor!
What about the electrical aspect? Special runners help connect and protect wires between panels and represent the only mounted equipment in the system. The wires eventually find their way to a big inverter inside the building, which feeds the electricity to us. A 2-way power meter can then feed any excess electricity back into the grid. Simple, right? Well, for a project this big and complicated you’d definitely want to hire some professionals. If you mix up which-wires-go-where, you could make some very expensive mistakes or just rob yourself of some of your solar power.
What if you and your neighbors want to go solar but can’t afford it? Bulk your order and get it done at the same time. Combining your orders will reduce costs in man-hours and equipment (think crane rentals). Naturally you can also get a better deal on the panels themselves if you buy in larger quantity.
** NEW: See an updated article about these solar panels here**
Images Courtesy of Patrick Bollinger.
Michelle:
Thank you for sharing the information about your company’s project. I hope that you will be able to update us as you gain experience with the system. I am always interested in real world experiences from the customer point of view that is not quite as - shall we say “slanted” - as the glossy brochures that companies provide.
It would be great to find out how large your installation is in square feet (or square meters) and how much total energy that it produces.
If there is any maintenance required, that would also be great information.
Looking forward to those updates!
Michelle,
I have been looking for information on the overall performance across a rooftop’s thermal temperature range of the Unisolar product. I asked one of the reps at the NRCA convention in Las Vegas and was promised the information but have not recieved any as yet.
I am aware that some solar solutions perform better at lower temperatures than can occur during the height of a summer day on a roof. Since this product is laid on the membrane, and it is dark, does it absorb much UV radiation and heat? If it does, how does it perform at these higher temperatures?
@ Tom:
These panels deal with the heat rather well; better than other forms of solar. Since they use different kinds and combinations of chemicals, each type of solar reacts differently. Here’s a link of Unisolar’s tech report. There are graphs and some detailed info concerning performance and temperature. (If the link doesn’t work, go to Unisolar’s website and click on Technology and Engineering ->
technology overview.
http://www.uni-solar.com/interior.asp?id=66
@ Rod:
Sorry I haven’t gotten back to you sooner, but I wanted to make sure my numbers were correct.
We installed 4,900 sq feet on our roof, which breaks down to 204 individual panels.
Each panel can produce a maximum of 136 watts at any given moment, under optimal conditions. Obviously on a daily basis the panels might produce less at any given moment. How much power they produce each hour/day will vary.
As for maintenance, my understanding is that there is none. Apparently they did studies and didn’t notice any significant effect on performance if you did/did not clean them. The wires connecting the panels will probably wear out before the panels do.
If you decide to look into panels, don’t worry too much about the brochures. Just look at the numbers and compare them to the competition. Obviously the companies will want to market their product, but they are required to give you a large amount of accurate information concerning their product. Just be prepared to understand what all those measurements and figures mean.
Excellent article, and very exciting to hear of a “real” project instead of a theoretical lab experiment. What sort of real/ actual power output can be expected from the installation shown on full sun and on cloudy days??
I guess with the much higher efficiencies now being reached (in the lab) with thin film PV cells - that this type of installation will become more and more viable with time.
Could I have your permission to quote section of your post and use the photos on my blog site??
Best regards, Tony McGinley. Ireland.
@ Tony:
I wish I could give you (and all our other readers) some real numbers for this panel on any given day, but at the moment they’re still finishing the last of the electrical work. Who knew there were so many wires?
I’m not sure if Magco intends to monitor the real-world output of their solar panels (wouldn’t surprise me if they did). Unfotunately this is my last week working with the company, so I won’t be around to monitor the system myself. I do, however, have all the contact information I need to write a follow-up post in the future. Stay tuned.
Tony, you can feel free to quote away! I’m glad you like my article *that* much. Some link love would also be appreciated, of course. If you have any other questions, just let me know.
I broke into the solar industry selling Uni-Solar installations six years ago. True, Uni-Solar’s triple-junction cells are easily the best thin-film photovoltaics on the market. The article above quotes 12% efficiency but if you click that hotlink you’ll see it is “beginning of life” production. Amorphous silicon PV–which is what Uni-Solar cells are–all experience a short-term burn-in period called the Stabler-Wronski effect. For some as yet uncertain reason, the electrons are hyperactive during this 60-90 day period thus producing more electricity. After that the cells settle into the 8-9% efficiency at which they’re actually rated.
Is this significant? Definitely, as average efficiency for standard silicon panels is around 13% with some as high as 20%. This means considerably less roof space is necessary for a crystalline panel system.
Uni-Solar PV does work well in various light conditions because of their wider spectral response to light. Some of my past customers here in San Diego marvel at how much power is produced by their Uni-Solar panels during heavy marine-layer overcasts. Furthermore, laminates are just .7 lbs per foot square and have that more “built-in” look. They also cost less per watt than silicon panels but not by much.
What is cost per foot of the thin panels?
I am a designer trying to incorporate thin film solar in to a project, who else, other than uni-solar, makes a similar product?
whats the price per Watt of this thin film panels?