There are over 8 billion square meters of rooftops on which solar panels could be installed in the US alone. This represents over 1 terawatt of potential solar capacity, which is roughly equivalent to all the installed solar power on earth today, or 6% of global energy consumption. Furthermore, recent advances in solar panel efficiency and usability are dramatically increasing the energy generation potential in buildings and creating new opportunities beyond the rooftop. As electricity costs rise around the world and increasingly tech-rich buildings look for efficiency solutions, the conditions are primed for a new dawn for solar power in the smart buildings sector.
“According to the United Nations’ 2019 report, energy consumption in the building and construction industry accounts for more than 40% of total global energy consumption. To achieve the objective of energy saving in buildings and indoor comfort improvement simultaneously, effective and reliable applications of renewable energy in buildings should be reasonably promoted,” reads the July 2022 special issue of Sustainability Journal: Utilization of Solar Energy in Smart Buildings. “Intelligently utilizing solar energy and other renewable energies in buildings can significantly contribute to energy conservation and CO2 emission reduction towards a sustainable society.”
As smart energy management systems drive efficiency to reduce energy consumption in buildings, recent advances in solar panel technology are increasing the electricity generation capacity in relation to panel size. In fact, the US Department of Energy's National Renewable Energy Laboratory just set a new solar cell efficiency record of 39.5%, and under normal lighting conditions using inverted metamorphic multijunction cells. These silicon cells are made of three stacked layers, each made of different materials that capture energy from different parts of the light spectrum.
Then, there are new Perovskite cells, “the solar industry’s shining beacon and simultaneous problem child,” according to industry commentator Matt Ferrell. Perovskites are thin, lightweight, and cheap to produce, have also set new records above 25%, but lose 10% of their solar efficiency after a few months of use, compared to standard silicon cells whose manufacturers can often guarantee 80% efficiency for up to 30 to 40 years. If solar’s “problem child” can solve its degradation issues then Perovskites could be commonplace in future buildings and smart technology. Perovskites could also challenge on rooftops unless silicon cells continue to lower production costs.
“Perovskites are ideal for powering IoT products. The solar cells are lightweight, durable, and suitable for all light conditions. They are much more versatile than traditional silicon cells,” claims Saule Technologies who began production in 2021 and is steadily announcing new licensing opportunities for products with perovskite PV integration. More recently, in April 2022 a study found that adding organic metallic compounds could help improve the cells lifespan, efficiency and stability. The enhanced cells maintained up to 90% of the cells original 25% power conversion efficiency rate after 1500 hours of use. It may take some time for Perovskite solar cells to develop these new innovations into production and on to full commercialization.
“But, what if making new solar cells was as simple as printing a newspaper?” asks Ferrell in his video exploring solar breakthroughs. “Organic power cells are made by printing photovoltaic material onto flexible materials like sheets of plastic. These paper thin solar cells are composed entirely of organic materials, flexible, lightweight and quick to manufacture with printing technology, the same process as printing newspapers, but here's the coolest part… Unlike silicon cells, the conversion rate efficiency doesn't drop when used indoors, which makes them extra appealing for devices like smart speakers, sensors and other wearables that may not see a lot of actual direct sunlight.”
Organic solar cells only reach efficiencies of 10-15% but the production cost is half that of silicon-based cells, and they're 100 times lighter. Each square meter currently weighs less than two kilograms, on average, and that figure is falling fast. Cheap and lightweight perovskite cells may have nearly double the efficiency but these organic solar cells have a far longer efficient lifespan of 20 years. However, it is the ability to capture ambient light that really sets organic solar cells apart from the other emerging technologies in the buildings space, while its ease of production has already seen it reach broad commercialization.
Sweden's Epishine launched its miniature solar harvesting modules in December 2021, boasting an energy conversion rate of 13% and a lifespan of 10 years. Their adaptable modules can be used for temperature and humidity control sensors, fire alarms, card readers, and other smart devices around the building. Meanwhile, Ricoh in Japan has begun smaller scale production of 100 square meters a year, but that's still enough to power 50,000 smart building devices.
German startup Heliatek began mass production of HeliaSol, an organic “solar film”, which is flexible, backed with an adhesive, comes ready to connect and is targeting rooftops and building façades. “HeliaSol is the perfect solution for retrofitting buildings where restrictions in terms of weight, static load restrictions or penetration of the roof material play a role,” the company states. Heliatek expects to produce 600,000 square meters of organic solar cells in 2022 and aims to ramp up to 1.1 million square meters per year in the future.
In France, Dracula Technologies raised €2.4 million ($2.48 million) to develop its “film-like” organic solar cells that do not rely on pricey rare-earth metals and are expected to start production by 2024. Around the world, organic solar companies are racing to production in order to meet the growing demand from smart buildings but also from the automotive market and even discussions on self-powered smartphones. Saur Energy International predicts that the global market for organic solar cells is to rise fivefold to more than $500 million by 2035.