The German solar company Heliatek has this idea that one day, cars will be covered in solar coatings that will enable you to charge up while scooting down the highway or parked in a sunny spot. That’s the big picture. For now, Heliatek is focusing on replacing your sun roof with an organic solar cell window treatment, and the company has just announced a major step forward in the efficiency of its organic solar cells.
Organic solar cells are far less efficient than their silicon cousins, but they are also far less expensive. They are also flexible and transparent (or semi-transparent), so they can be used over a huge range of applications including buildings and yes, cars.
Heliatek’s New Organic Solar Cell Record
When organic solar cells (or OPV for organic photovoltaic cell) first emerged, efficiencies hovered around the 3 percent mark, and that’s where Heliatek was at. That sounds pretty dismal, but that was about ten years ago. Things improved at a relatively rapid clip and by 2013, Heliatek was reporting a solar conversion efficiency of 12 percent.
Heliatek has also been adding to its investor list. It kicked off with an all-star roster including Bosch and BASF, and in 2014 it added another round of impressive backers.
Heliatek’s new organic solar cell record, just announced last week, clocks in at 13.2 percent as confirmed independently by the solar research center Fraunhofer CSP. That’s still not up to the company’s end goal of 15 percent but for now nobody is complaining, especially not Heliatek CEO Thibaude Le Séguillon, who provided this remark to the media:
I am delighted by this latest result. It validates our choice to internalize our R&D, both by developing new absorber molecules and optimizing the device architecture. This will provide the baseline for efficiency in our large-volume manufacturing line. With our HeliaFilm®, we are clearly executing our strategy to provide de-carbonized, de-centralized energy generation directly on buildings all over the world.
The new Heliatek consists of three layers of organic molecules, each of which has been developed in-house by Heliatek. Each layer specializes in converting green, red, or near-infrared light for a total range of 450 to 950 nm, which accounts for its relatively high efficiency.
The substrate or bottom layer is flexible plastic, and the whole thing can be put together using conventional, high volume vacuum deposition and roll-to-roll technology, which accounts for its low cost.
For those of you new to the topic, the new solar cell is called “multi-junction” because it uses more than one material. Here’s how such a cell looks with two layers:
The Solar-Powered Car Of The Future
When we first caught up with Heliatek, its main ambition was to transform window glass and other building elements into built-in solar power generators, so the skip over to power-generating sun roofs isn’t that far of a reach.
For starters, Heliatek is putting out feelers for solar sun roof manufacturing partners. The idea would be to increase and stabilize interior comfort without drawing excess electricity from the battery. In effect it would act as a range extender for electric vehicles as well as a gas-saver for gasmobiles or hybrids. The solar-equipped sun roof would also enable you to operate electronic equipment while parked, without sacrificing battery range (or having to idle your car, in the case of gasmobiles).
Heliatek is also exploring applications for the trucking industry, as a means of shaving power consumption during peak use periods.
As for whole-body solar coatings for cars, that’s still a long way off. However, R&D on low-cost, spray-on solar “paint” is progressing, and we notice that our friends over at the Tesla Motors forum were kicking the idea around a couple of years ago.
For that matter, in 2014 Mercedes-Benz rolled out its vision for the G-Code, a solar painted car:
Sweet, right? As far as we know you’ll have to go to China to get behind the wheel of this thing.
However, US drivers can take heart. Just last Friday the US Department of Energy’s Office of Technology Transitions announced that it has issued its first ever solicitation for proposals to bring “cutting-edge” technologies to market:
The office’s Technology Commercialization Fund (TCF) has been newly infused this year with $20 million from across the Department. The funds will be used to advance promising energy related technologies with commercial potential and help strengthen partnerships between the national labs and private sector companies that can deploy energy technologies to the marketplace.
That’s significant because the US National Renewable Energy Laboratory has been all over organic solar cells like white on rice, and it is already partnering with the private sector on ramping up OPV efficiency.
The new cash infusion should help step things up a notch, so stay tuned.
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Image credits: top two via Heliatek, bottom (cropped) via Mercedes-Benz.
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