German startup develops tinted windows that generate electricity

The next great advance in solar power generation is always right around the corner, right? New solar technologies are often much less impressive in practice than they are on paper, but a startup called Heliatek may finally have something to really shake up the energy sector. Heliatek, which is based in Dresden, Germany, has modified techniques used to make touchscreens to create a translucent solar cell that can be used as a tinted window.
Heliatek’s new transparent solar panels are very similar in design to OLED displays. Both rely on a thin layer of organic molecules deposited on a flexible backing. The idea of printing organic solar cells like this isn’t new, but past cells printed in this manner tended to have very short lifespans. Heliatek is getting around that problem by using shorter chains of molecules, known as oligomers, instead of more fragile polymers. The result is a panel with a usable life more like that of conventional silicon solar cells.
Efficiency is the holy grail of solar cells, and it’s the unique application of oligomers that makes these new transparent solar cells technologically feasible. The precise layering of molecules allows Heliatek to tune the panels to more efficiently absorb certain wavelengths of light. The Heliatek solar panels convert 9.8% of light into electricity, whereas regular solar panels can slurp up 15% or more. That sounds like a major issue, but there’s a bright side.
Solar technology has historically only been truly useful in areas with lots of sunshine and high temperatures, but the Heliatek panels are actually more efficient in low light conditions than regular cells. The result is that in areas not particularly suited for solar power generation, the Heliatek technology can generate more power over time. This is based on recent tests in Singapore where the semitransparent panels beat out old-fashioned silicon ones over a one month period.
Heliatek hopes to be able to push the efficiency of its solar cells to 12% while keeping the same tinted glass effect. If it can do this, the company believes it will see increased interest from builders. A flexible solar cell that can act as window tinting could be a huge money saver. Conventional solar panels require that space be set aside, and mounting points be added. Maintenance on these systems can also be costly. Buildings already have windows, so why not put them to work? Imagine that all those skyscrapers, gleaming towers of metal and glass that they are, were generating power with their windows.
Perhaps the biggest hurdle Heliatek will have to deal with is a depressingly realistic one. After seeing “the next big thing” in solar technology rise up and fade away so many times, banks are wary of funding the installation of unproven technologies. The collapse of the US firm Solyndra a few months ago definitely spooked a great many solar advocates too.
For all their inefficiencies, the inflexible and opaque solar panels from years gone by are still the easiest to fund. Unlike some past solar power claims, Heliatek doesn’t set off my skeptical alarm bells. Heliatek seems to be taking a measured approach, and acknowledges the difficulties it faces. The German company will have to prove its technology can work in the field before it will see wide adoption, but that’s something we can all root for.