Perovskite solar cell technology on the road to commercialization

From pv magazine Global

Achieving the US government’s decarbonization goals of 100% carbon-free electricity generation by 2035 and net-zero economy-wide carbon emissions by 2050 will require the deployment of record levels of renewable technologies. The most common solar technologies deployed to date are crystalline silicon and cadmium telluride (CdTe), the costs of which have dropped markedly in recent years. The US Department of Energy Solar Energy Technologies Office (SETO) said in order to meet 2035 targets, solar deployment has to double in the next three years, and ultimately ramp up to 100 GW by 2035.

While most development will use silicon and CdTe, SETO sees potential in nascent technologies like halide perovskites.

SETO finds that the power conversion efficiencies (PCE) of halide perovskites (over 25% in single-junction cells and over 29% in tandem cells with silicon) show promise. One advantage of perovskites is that they can be easily manufactured in high volume. However, significant technological challenges must be addressed before perovskites are ready for commercial power sector markets.

In a recent Energy Focus report, SETO covers the critical technical barriers, the commercialization pitfalls and opportunities, and efforts to overcome barriers and challenges to commercialization. It also references SETO-funded projects, which can be viewed in the Solar Energy Research Database.

One of the major barriers is cost. In order for perovskite to be commercially competitive, its levelized cost of electricity (LCOE) must be competitive with that of other technologies. And with the cost of silicon and CdTe modules dropping while warranty times are increasing, it will be a steep challenge for perovskite to compete on an LCOE basis.

“As researchers continue to develop perovskites, there are lessons to be learned from the fates of other photovoltaic technologies. SETO is focused on helping perovskite photovoltaic companies to avoid those pitfalls and spurring innovation in order to get this technology market-ready and accelerate the deployment of solar energy,” said Dr. Lenny Tinker, photovoltaics program manager, Solar Energy Technologies Office, US Department of Energy.

Module and cell durability

Durability is the largest technological risk for perovskite PV. For LCOE metrics to approach SETO’s 2030 goals of $0.02 kWh, perovskite PV will have to last at least 20 years in the field, which will require improving its ability to withstand various environmental conditions. Much testing is required, yet today’s tests are geared toward commercialized PV technologies (Si, CdTe, etc.) and are unlikely to capture all the failure modes relevant to perovskite modules in the field.

Existing tests may also be excessive or promote irrelevant or uncharacteristic modes of perovskite device failure. SETO has published some minimum durability performance targets which, if realized, would provide strong evidence that a prototype perovskite PV device is ready to enter an initial production stage. To this end, SETO funds considerable perovskite durability work as well as development of test standards.

Efficiency, often considered a strength of perovskite PV, requires significant improvement for large-area devices before they are ready for the commercial arena. While standardized cell and module form factors have yet to be finalized for perovskite PV, standards will be a crucial prerequisite to scaling the entire industry beyond initial demonstration projects.

To encourage industry standardization and communication, SETO is promoting collaboration among academia, the national laboratories, and industry – intended to bring diverse perspectives and expertise to bear on common problems, accelerate cycles of learning, and facilitate transfers of knowledge and skills. Industry consortia like PACT and the US Manufacturing of Advanced Perovskites (MAP) consortium allow companies to connect and share best practices within this industry.

The final major technical hurdle to commercialization is achieving high production yield, with narrow distributions in module efficiencies. Barriers related to process control and manufacturing yield are often underappreciated, and perovskite solar cells have not yet demonstrated broad process flexibility in the lab. Cost-effective deposition processes will need to tolerate small variations in factors such as deposition tooling conditions, deposition environment, and ink compositions.

SETO has emphasized process control in perovskite projects across its portfolio, ensuring that changes in performance or efficiency are statistically significant and robust from a process standpoint, while funding the development of processes which, when scaled up, might be easier to control.

The ability of perovskite PV technologies to secure investor financing with low interest rates, may be even more significant than the technical challenges to perovskite PV commercialization.

Financing will be necessary for scaled manufacturing lines and deployment projects. Bankability is directly related to the confidence financers have that (1) the technical challenges have been solved, (2) the financed assets will perform long enough to deliver a desired return on investment, and (3) the liability of product failure and warranty claims is low. Ensuring bankability and durability standards are met is a SETO priority.

Future opportunity

These challenges faced by perovskite technology makes it uncertain as to if and when it can achieve gigawatt-scale deployment. In the meantime, there are many different applications that can support higher dollar-per-watt costs and durability issues including transportation, building integrated PV, military operations, aerospace, and Internet of Things. Substantial capital will be needed to scale the perovskite industry, which will come only once investors and financiers have confidence in the profitability of perovskite manufacturers and the long-term durability of perovskite module technologies.

Sustainable growth of the perovskite industry depends on avoiding these pitfalls and requires patient and careful investment that corresponds with the timeline and magnitude of progress needed to adopt this technology into products.

SETO has supported a wide range of perovskite startups in various stages of development, through different programs, as SETO can support sustainable investment in the perovskite PV space by providing nondilutive capital to promising early-stage commercial entities. Startups further along in the product development cycle and closer to pilot manufacturing are encouraged to apply for funding through SETO’s Incubator program.

Overall, the opportunities for perovskites as a solar technology are great. It has the potential to develop into a high-efficiency, low-cost module technology for commercial power sector deployment, with throughput rates and energy payback times superior to state-of-the-art PV technologies. SETO calls for members of the perovskite community increase device size, demonstrate relevant outdoor durability, and make processes robust in order to tap the potential of perovskite in the solar energy sector.

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