There are multiple potential long-term impacts from this project. The potential for integrating small solar cells into the wireless sensors needed to power the fast-growing internet of things (IoT) ecosystem, many of which are located indoors, is large. This market could represent a unique opportunity for thin film PV technologies, and perovskites in particular, to reduce the risk inherent to ramping up commercial scale production. The market for indoor PV cells, such as those used to power watches and calculators, was worth just US $140 million in 2017. But price reductions in solar are beginning to line up with decreasing energy requirements for technologies such as wireless sensors, RFID tags, and Bluetooth beacons. We predict billions of these sensors will be installed in the coming years, despite their current reliance on battery power, leading to sacrificed performance for increased battery life, and additional operations and maintenance costs associated with replacing these batteries.
Integrating PV cells into the devices could solve a lot of these problems, leading to a boom in the indoor PV market, surpassing $1 billion annually in 2024. Around half of the sensors are expected to be placed indoors, with little or no access to sunlight, meaning the PV cells would have to rely artificial light, typically at intensities three orders of magnitude lower than sunlight. Our techno-economic analyses so far, suggest that the poor low light performance of silicon would not make it a good candidate for indoor PV applications, opening the door for various thin film technologies. Emerging technologies including GaAs, organic PV and perovskites have exhibited the kind of low light performance needed for indoor PV, and their well-documented stability issues would be less of a problem in an indoor setting. The type of sensor being powered may have a lifetime much shorter than the 20 years plus which has become the industry standard. For perovskites in particular, we theorize that the indoor PV market could provide an opportunity to mitigate many of the risks associated with commercial introduction: Our market analysis makes it clear that the rapid growth of the indoor IoT market could provide an ideal jumping-off point for perovskite products, allowing a new PV company to establish customers, revenue, and credibility before establishing larger-scale solar panel manufacturing facilities.
