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Clean Power Heliatek solar car vision

Published on February 8th, 2016 | by Tina Casey


New Record For Organic Solar Cells Today, Solar-Powered Car Tomorrow

February 8th, 2016 by  

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 solar car vision

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:

organic solar cell Heliatek

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:

G-Code solar 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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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • infinityPV

    Really good progress what Heliatek is doing but the solar powered car is bit toooo futuristic, even with 100% efficient cells.
    Organic solar cells can also look like this

    • I agree that weren’t going to see a self contained solar powered car. There is just not enough surface area to effectively generate enough energy to recharge the batteries to be practical. Plugging in or battery swaps will still be needed. Though that can be powered by current solar solutions.

  • ADW

    Not a bad idea, but I prefer them to focus on window system for homes/buildings. With my car I rather park under a PV canopy I can plug into and charge while being shaded.

    Note: 10 years ago this was very pie in the sky at 3%, but today we thinking “getting dang close”. What will solar be like in 10 years time? (along with wind, geo-thermal, etc etc)

    • JamesWimberley

      Windows are fairly complex. House or ship paint would be the stuff. But doesn’t the electrical circuitry require standard-size units like tiles, or panels? I have a feeling that this idea is going to stay on the shelf a long time.

      • Frank

        I’m curious how long this stuff is supposed to last. I also wonder if they could put it on corrugated roofing. That would have to be cheap, and the surface isn’t flat, but it’s big.

  • Martin

    With all the new ways of solar to electric power, it will be just a matter of time that buildings will be able to create just as much power as they consume or better even create more power that they need.
    Really cool, just like “Back to the Future”, can wait until we get there and off FF!

  • Preston C.

    I tried a back of the napkin calculation to see approximately how much you could get from solar paint/windshield on the entire car. Top down area of model S: 9.77m^2. 1000W/m^2 multiplied by 9.77m^2 multiplied by 0.13 efficiency = 1270 watts. Multiplied by 4 hours sunlight is equal to ~5kWh per day. This figure will definitely be lower as the angles of the car will not be the best and it also depends on if they can achieve the 13% efficiency on car paint as well as sunroof/windshield. It does look fairly promising if they can get the price down low enough. You could potentially power the heater and seat warmers in the winter without a range hit?

    • vensonata

      Thanks for sparing me a napkin. 5 kwh is nothing to sneeze at. I had dismissed the PV on the car idea as never amounting to anything, mostly because PV expense is better invested in optimal surfaces. But if the PV is cheap enough the surface doesn’t have to be optimal to make economic sense. Let us imagine a best case scenario where we hit efficiency of double the present…that is 25% efficient. Now one might reap 10 kwh day parked on the sunny side of the street. That could cover actual average mileage per day in an efficient EV. So yes…we may have to re think this formerly dismissed idea.

      • eveee

        I agree. Its not so far fetched. The question is how the alternatives compete. If workplace charging isn’t happening or too expensive….
        Also, battery capacity costs drop. That competes because of home charging. But the real kicker is how much the car can provide to the home via V2G at night if the utility switches to TOU and boosts the evening rate.

        • Benjamin Nead

          I briefed over the organic solar cell R&D part of the article with skeptical enthusiasm, as this is pretty much reads like yet another battery breakthrough press release: believable when it actually gets here, but we ain’t there yet.

          Solar PV built into the roof of an EV . . . ugh! I still talk to people who simply don’t comprehend the vast amount of today’s conventional PV it takes to directly run a street legal car – even a subcompact one, like my i-MiEV – on sunshine for more than a few blocks after sitting outside all day long (as opposed to an 800 pound skateboard that carries only a single human with no extra cargo in cramped, uncomfortable conditions and is completely covered in panel.)

          But, if you can concentrate the efficiency of that PV panel down to something that someday that could fit into a sunroof slot (hadn’t thought about that idea before . . . nice modular installation that can be easily removed in case of service/replacement) and get 5kW out of it after several hours of direct sun exposure . . . then, yes, that is significant. Beyond adding around 20 miles range, I could also leave my EV parked in direct sun on a particularly scorching day and run the air conditioning for hours at a time.

          • eveee

            Thats right. At a bit over 5kwhr, it gets interesting. Only needs to be daily commute amounts. And if it doesn’t get that much all the time, not a deal breaker. What is a deal breaker is putting it on fenders and hoods. The cost of fender benders could go up too much. And you have to wonder about waxing, UV, and all that stuff. But beyond that, I am reasonably optimistic.
            Cost vs payback has some issue, too.
            The best way to leverage it is in reduced battery cost or effectively increased range.
            Its a funny concept. Plug in EV solar hybrid. It doesn’t run on solar all the time so it needs a plug. 🙂

          • Bob_Wallace

            Aesthetics. Need to keep aesthetics in mind.

          • eveee

            Yup. If it makes it look good, OK. If it comes out ugly, it won’t sell. I kinda like the Nissan Leaf dust free paint idea. Have not seen it in person. The little solar panels on the rear spoiler are OK by me. Don’t know if they made any difference to car owners.

      • Jenny Sommer

        It could maybe cover the AC when your car is hot inside from parking in the sun…
        You might only get 1kWh/day or less from your dirty, partially shaded car.

      • vensonata

        The horizontal surface area of a Model S is about 100 sq feet. At 20% efficient PV which is currently available that would produce 3000 kwh per year in Las Vegas on a flat roof. Say 8 kwh day on average. Those figures are from PV WATTS. That does not take into account any vertical surfaces which could increase the area by 50%. So all things considered, dirt, shade, etc. it actually could be a viable option at the right price. And for some just the convenience of always having some positive charging going on would be enough to add this “feature”.

    • eveee

      A daily parking at the office would net 8 hours a day. Between inefficiencies, etc, it probably does come out to 5kwhr/day. That would give you 15 miles or more in a Model S. Not hard to see a stretch to a more efficient EV, and a bit more sun going to 25 miles.

    • Zé M. S.

      You get 1000W/m^2 in a sunny summer day with sun at 90 degree angle with the solar panels.

      As an example at latitude 39 you wont receive around 15% of that energy (considering the panels are parallel to the ground). And in a winter day there’s 1/4 of the energy of a summer day. So in the winter we’re talking at a maximum of 1270/4 = 317W. With some clouds, the losses from the geometry of the car and some shadows from buildings, trees etc, we’re probably talking about 50W-100W.

      I still think this is interesting as way to avoid battery losses while the car is not charging, and even charging the car during the summer if for example the car is left in a airport parking lot during vacations, for people who drive just a few miles every day and to extend the range during trips.

      • omar

        We have sun shining the hall year, in summer the temperature is 50 degree celcious how much efficiency efficiency will drop in temperature like this ?

        • Zé M. S.

          Some panels perform better than others, for each manufacturer you have the “temperature coefficient (Pmax.)” value. Let’s assume Pmax = -0,5%.

          The panels are tested at 25ºC, for each degree above you lose ~0.5% efficiency. If the air temperature is at 50ºC, the panel (without cooling) could reach as high as 88ºC (estimated value), that’s 63ºC above 25ºC, therefore: 63*-0,5 = -31,5%. So:

          13% efficiency => Real Output = 9% efficiency (-4%)

          25% efficiency => Real Output = 17% efficiency (-8%)

          But when the car is moving the temperature will decrease a bit, can’t find any way to calculate how much it decreases.

          • Preston C.

            From what I have read these organic solar cells perform better than standard solar panels at higher temperature.

            I think if they could get the price around $1000 to cover all the painted area of the car minus bumper then it would be worth it.

          • Zé M. S.

            “I think if they could get the price around $1000 to cover all the painted area of the car minus bumper then it would be worth it.”

            I agree.

          • omar

            If there is no cooling system what do you think about frequent water drop to the surface of the panel ? with wind should bring some coldness

          • Zé M. S.

            Spraying the panels with water is a cooling system ;-).

            I guess anything that brings the temperature down is a good solution.

    • Jens Stubbe

      Should you not calculate with the entire area of the car body ?

      And why 4 hours daily ?

      • Preston C.

        You’re right, you would need to calculate the whole area that is planned to be covered with solar ie. windows, door paint. My estimation was very rough and took about 3 minutes. Try to calculate the total area, i’m interested to see how much there is. There would be diminished returns on the surfaces like the doors and windows though as they would not get direct sunlight, so it would have to be extremely cheap to cover them to be worth it.

        The 4 hours daily is just an estimate of direct over your head sunlight that I have seen used in certain rooftop solar estimations. If you had solar paint/windows on the side of your car you could benefit from earlier/later in the day as the angle of the sun would be closer to the horizon, but they would be effectively useless when the sun is overhead or on the other side.

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