Transparent Solar Windows Reach a Working 30-Centimeter Module

UCL researchers built semi-transparent perovskite solar cells that could let building windows generate power.

Researchers at University College London have built semi-transparent perovskite solar cells designed to work as windows, publishing the results in Advanced Energy Materials with PhD candidate Siming Huang as lead author. Their prototype transmits about 30% of visible light, well below the 80 to 90% of ordinary window glass, and the demonstrated 30 by 30 centimeter module reached 14% solar conversion efficiency. Under bright indoor light, individual cells hit 22%.

The design relies on a 1.7 eV perovskite layer roughly 185 nanometers thick, paired with a layered top electrode tuned for transmittance. To keep the crystal structure stable and cut down on defects, the team added a triazole molecule. Separately, Kentucky startup Sofab Inks, spun out of the University of Louisville, reports 22.3% efficiency on similar-sized single-junction modules using a fullerene-free formulation, and closed a $6 million seed round led by Cloudberry Ventures in July.

If window glass can double as a power source, the economics of building energy shift. Surfaces that were previously dead weight become generators, which matters most for tall buildings where roof area is small relative to facade. That expands where solar can be captured without new land or dedicated panels.

The honest caveat: this remains in development and scaleup. The efficiency figures come from the researchers' own study and, for Sofab, from company statements. Perovskite durability at building scale and over years of weathering is the open question these lab results do not yet answer. Watch whether the 30-centimeter module scales to real window sizes and holds performance.

Source: CleanTechnica