The era of solar power derived from indoor, low-light sources is upon us.
A small cadre of startups have developed advanced photovoltaic (PV) cells capable of pulling in significant amounts of power from indoor "ambient" light sources, and they're attempting to bring it to the masses. Their advanced cells could allow product designers to take a fresh approach to products that require disposable batteries and eliminate a common pain point: the hassle of replacing disposable batteries.
Ambient Photonics, which began as a project within the Warner Babcock Institute for Green Energy, itself a subsidiary of the venture firm Cthulhu Ventures, developed a PV technology inspired by the process of photosynthesis in 2019. Since then Ambient, based outside of San Jose, California, has announced several partnerships to create light-powered smart devices, including with E ink, the company responsible for the ePaper technology that powers Amazon's Kindle e-reader.
Ambient and E ink are collaborating to create next-generation electronic shelf labels, essentially tiny screens displaying product and pricing information in retail stores, that can be powered entirely through indoor light. Many stores in Europe are outfitted with these electronic labels, with larger stores responsible for maintaining anything from 30,000 to 50,000 labels.
"These labels have taken off because they bring the pricing agility you can find online to brick and mortar locations," says Bates Marshall, Ambient's co-founder and CEO "But each is powered by two or three coin batteries that eventually have to be replaced. That's bad for the planet, but it's also a big operating expense." By harnessing power from the store's own lights, Marshall says businesses can fully eliminate that expense.
"Businesses know that digging coal out of the ground and burning it creates negative externalities, like pollution and acid rain, which is why solar and wind now make up 95 percent of new energy on the grid. As companies come under pressure to go carbon-neutral over the next few years, they'll need to do more to offset their emissions than just buying carbon credits--they'll also need to change their disposable battery usage," Marshall says. "We see our message as two-pronged: We're helping businesses go carbon neutral and we're eliminating the time and money wasted by replacing batteries."
While Ambient is focused on producing PV cells capable of powering IoT devices without sunlight, Swedish company Exeger, founded in 2009, has its eyes on the consumer electronics market. The company is the developer of Powerfoyle, a proprietary brand of ultra-thin flexible PV cells that can be customized to take any shape. In 2021, Exeger released its first product: Self-charging over-the-ear headphones, in which the PV cell is built into the device's headband.
Exeger in 2022 released a similar pair of headphones in partnership with Adidas and has also teamed up with 3M to develop a self-charging communications headset designed to be used by construction workers or air traffic controllers. Other product collaborations include a light-powered TV remote for the tech conglomerate Phillips.
Among the downsides of the PV technology is that it can pretty much only power devices that would otherwise use disposable batteries. "I'd be happy to sell you a 10 square meter cell to wear on your back," says Jérôme Vernet, vice president of sales at French PV startup Dracula Technologies, "but I don't know how marketable that would be."