Perovskite solar technology taking a step forward

Perovskite solar technology set to be commercialised in tandem modules alongside polysilicon cells

Solar technology developer Caelux (which spun out of the California Institute of Technology in 2014) announced plans to commercialise its Caelux One sub-module perovskite solar glass. The technology is intended for use in combination with existing polysilicon based solar cells to produce so called ‘tandem’ modules. The combination will increase the conversion efficiency of a conventional polysilicon module by c.6 percentage points. Conversion efficiency refers to the portion of energy in the form of sunlight that can be converted into electricity by the solar cell. The average solar cell operates at 15-20% conversion efficiency while the latest, highest efficiency cells presently available are quoted at c.24%, so this development is a meaningful step forward.

The company has successfully developed a method for depositing a perovskite solar cell within glass. This glass can be integrated into a conventional polysilicon solar module (irrespective of the specific technology variant, i.e. PERC, HJT or TopCon) with minimal changes to the manufacturing process.

The company plans to open a perovskite glass manufacturing facility in Los Angeles, California with capacity to produce 100MW of perovskite solar glass per year. The company is targeting a commercial launch in 2024 with plans to scale by 10x thereafter.

Hurdles to commercialisation

Perovskite solar technology is fairly new (its first reported application was in 2009, whereas crystalline silicon applications date back to the 1950s) and has struggled to achieve success outside of the lab. The main challenge is its sensitivity to moisture in ambient air which causes degradation of the cell and therefore its photovoltaic property. Embedding the technology within glass mitigates this problem.

Advantages vs polysilicon-based technologies

Perovskite cells have various advantages including: 1) tolerance for structural defects (unlike polysilicon which requires extremely high purity, without imperfections in order to function effectively) which means lower manufacturing cost; 2) thin film architecture which can be printed or sprayed-on (unlike a silicon-based technology which must be incorporated into a panel) which means it will not only be thinner and lighter than other solar cells (including existing thin-film photovoltaics such as cadmium telluride) but it has the potential to be used in a much wider range of applications; 3) higher theoretical conversion efficiency at c.30% for a single cell relative to c.25% for polysilicon cells; and 4) superior performance in extreme weather conditions (based on a lower temperature coefficient).

Lower cost

The early indications are that perovskite solar technology can be produced at least as cheaply as the lowest cost existing polysilicon-based technologies and considerably cheaper than other thin-film photovoltaics. We see considerable potential for perovskite’s economics to be improved materially over time through manufacturing scale and the technology learning curve.

Caelux is not the only developer working on perovskites and not even the only developer working on tandem modules (we note that Caelux’s industry peer CubicPV recently publicised its continuing development of tandem modules).

We see the level of activity and achievement of milestones in perovskite as more evidence of the trajectory of solar technology generally which reinforces our expectation that we stand to see extraordinary things from the solar industry in the years to come in terms of efficacy of technology, a much wider range of form factors and considerable industry growth (both in terms of manufacturing and importance in the global energy mix).