Vertical Solar Farms in Cities

In the recent James Dyson Awards of 2020, the first-ever Sustainability Winner went to the AuREUS system, developed by Carvey Maigue, a student at Mapúa University in the Philippines. The AuREUS system utilizes technology synthesized from crop waste to absorb stray ultraviolet (UV) light and convert it into clean renewable electricity. It is aimed at creating better access to solar energy to aid in mitigating climate change while also supporting the local agriculture industry through mitigating losses from natural disasters ruining crops.

The two AuREUS devices—Borealis Solar Window and Astralis Solar Wall—use luminescent particles that absorb high-energy particles and re-emit them as visible light. These luminescent particles can be sourced from certain organic fruits and vegetables, helping tackle the issue of waste produce. The particles are suspended in a resin substrate and used as the core technology in both devices. When hit by UV light, the particles absorb and re-emit visible light along the edges due to internal reflectance. The light is then captured by photovoltaic (PV) cells that are placed along the edges, converting the light into direct current (DC) electricity.

As many cities around the world continue to develop, buildings are consistently being erected to cater to the needs of the population. Due to both cost and cosmetic reasons, glass is the number one choice as a material used in modern buildings. Buildings with glass facades typically have a coating on them that both reflects and absorbs some of the sunlight, both in the visible and infrared parts of the spectrum. This is to reduce the brightness and heating inside of the building. Rather than letting that energy go to waste, transparent solar panels and the AuREUS system provide alternatives to utilizing that energy to supplement the building’s electricity needs.

Traditional solar panels use conventional solar cells that are opaque, limiting their use to only specific applications such as on rooftops or in large solar farms. Companies like SolarWindow Technologies have developed a transparent liquid PV coating that can be applied to pre-existing windows forming small solar cells. This coating works in all kinds of lighting conditions including natural, low light, and even artificial or indoor light. The company claims that their product can outperform current solar panels by as much as 50 times when modeled for a 50-story building. Last year, Ubiquitous Energy partnered with global glass manufacturer NSG Group to develop, manufacture, and integrate Ubiquitous’s ClearView Power technology into architectural window glass. The company’s transparent solar cells managed to achieve a 9.8% power conversion efficiency. Smart city use cases have also been developed by companies like ClearVue Technologies, an Australian company, through its ClearVue PV window panels. These panels can be used to provide a smart facade that automatically adapts to lighting conditions by having self-powering motorized automatic blinds that respond to sunlight levels and requirements of the occupants.

While transparent solar panel technology paints an exciting picture for the future, it is relatively nascent at this point with challenges relating to efficiency and costs that need to be addressed and overcome. Currently, transparent solar panels have an energy conversion rate ranging from 5% to 10% as compared to traditional solar panels that are able to achieve between 20% to 25%. In terms of costs, Sharp Corporation in Japan provided estimates in 2013 that an 11-square-foot transparent solar panel would cost approximately US$2,000, which is more costly and less efficient than a window and solar panel of the same size. However, the technology has grown over the years and has proven to be a potentially strong contender in the solar alternatives industry.

According to the ABI Research market data Smart Cities, it is forecasted that the global smart cities tech investments will reach US$2.34 trillion by 2025, from US$1.48 trillion in 2020, growing at a 5-year CAGR of 9.6%. The strong growth and development of smart cities around the world would require as many alternative energy sources as possible to power the multitude of connections. It is therefore important for transparent solar panels to continually develop to improve on the efficiency levels and at the same time drive cost down to allow for mass production. With this technology, buildings could be turned into vertical solar farms across the city that generate large amounts of energy to be used to supplement the city’s energy consumption. The use of digital twins can further aid in calculating the total solar energy potential of buildings and entire cities. Furthermore, it can be used during the design phase of buildings and entire neighborhoods to optimize and maximize the solar potential. As transparent solar panel technology grows further into the future, it could potentially be integrated into vehicles, cellphone screens, and other everyday products.