Rooftop-Ready Perovskite Solar Cells Are Coming To The Residential Market – CleanTechnica

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Global solar capacity is shooting upwards, and the pace is set to accelerate as new, high efficiency solar cells emerge from the research lab. In that category are solar cells made with perovskite, a new class of synthetic material that promises low cost and high-volume manufacturing. After years of R&D, it’s finally ready for rooftops.

The Perovskite Solar Cell Of The Future Is Here

The natural mineral perovskite was discovered in the 1839. Nothing much happened in terms of solar technology until 2009, when a research team in Japan showed that perovskite crystals could be deployed in a solar cell (see more perovskite background here).

The solar conversion efficiency of their new device was a measly 3.8%, but it was a good start. Since then, conversion efficiency has shot up into the 20% range as the scope of research expands.

One promising pathway is to combine perovskites with the more conventional solar material, silicon. Silicon is pricier and more efficient, and perovskites are less expensive but less efficient. Combining the two materials in the right balance would lower the cost of solar cells while maintaining a reasonable degree of efficiency.

Oxford PV Applies Unprecedented Perovskite Solar Cells To Residential Rooftops

The UK firm Oxford PV, a spin-off based on Oxford University perovskite solar cell research, is among those working on tandem silicon-perovskite solar cells. In the latest development, Oxford PV reports that its new residential-sized solar module has achieved an”unprecedented” solar conversion efficiency of 26.9%.

“The breakthrough double-glass module, with a designated area just over 1.6 m2, weighs under 25 kg and is an ideal size for residential applications,” Oxford PV explained in a press statement dated June 20.

The figure of 26.9% was confirmed independently by Fraunhofer CalLab, an accredited solar calibration laboratory.

The new module is made from solar cells that layer perovskite on silicon. According to Oxford PV, the figure of 26.9% is well above the current status of silicon alone, which the company puts at about 25% efficiency for the most advanced modules.

With Great Efficiency Comes Lower Costs

A gain of 1.6% conversion efficiency may seem like small potatoes, but with greater conversion efficiency comes the same amount of solar power in a smaller footprint. That can translate into lower costs for manufacturing, transportation, and installation.

The increased efficiency also means that fewer solar panels are needed to provide the same power output. That could open up the market to smaller or partially shaded rooftops.

“Homeowners along with commercial and utility customers will all benefit from upwards of 20% more power with the same footprint,” emphasized Oxford CEO David Ward.

“Not only does this save installation costs, it also speeds up the decarbonisation journey and can contribute to the global energy transition in a meaningful way,” he added.

The Long Road To Commercial Tandem Perovskite Solar Cell Manufacturing

It remains to be seen how the real-life costs work out, but Oxford PV is ready for action. The company anticipates that it can scale up production of its new tandem solar cell to the gigawatt level over the next several years.

Meanwhile over here in the US, the Department of Energy has been a big fan of perovskite technology. They cite the relatively low cost of perovskites, the potential for high volume, high-throughput manufacturing, and the rapid pace of conversion efficiency improvements.

The fragility of raw perovskites in early-stage research was one obstacle to overcome. Combining perovskites with the durability of silicon has provided one solution, and the Energy Department is determined to get that to the factory floor as soon as possible.

Last September, the Energy Department put out the call for innovative firms to lay the ground work for mass-producing a tandem perovskite-silicon solar cell under the umbrella of its PRIMES Perovskite Tandem PV program. The agency cast a wide net, inviting other materials into the tandem fold in addition to silicon.

“Projects in this topic will focus on hybrid tandem devices that combine perovskite PV with another PV material,” the agency’s Solar Energy Technologies Office explained, noting that PRIMES is offering awards from $1 million to $5 million.

SETO noted that winning applicants would meet “specific efficiency, long-term reliability, manufacturability, and economic viability thresholds,” indicating a focus on meeting the demands of the market.

…Is Getting Shorter

The awardees were announced in May. Among them is the California firm Tandem PV, (formerly Iris PV), which nailed down an award of $4.7 million.

“The selected project will help Tandem PV prove out its revolutionary pairing of conventional silicon solar with perovskite materials for panels that have the potential to be up to 40% more powerful than those used today,” the company stated.

“The company is producing tandem perovskite panels with roughly 26% efficiency, which is already 25% more powerful than the typical silicon solar panel,” the company notes. “More power at a similar price per watt leads to lower labor costs for installation, lower land-acquisition costs and a lower total cost of ownership for customers.”

More Tandem Perovskite Solar Cells Are On The Way

If and when Tandem PV’s new solar cells make it to the US market, all taxpayers can give themselves a big group hug. The company launched in 2016 as a spin-off from Stanford University. It was one of the first startups to garner support from the Energy Department’s Cyclotron Road accelerator, which opened for business the previous year. The National Science Foundation and the California Energy Commission have also chipped in, along with additional venture capital funding.

Meanwhile, researchers are still exploring different strategies for solving one foundational challenge in the perovskite solar cell field, which is the tension between conversion efficiency and durability.

That nut is also beginning to crack. Earlier this month, a team at Rice University reported on a new method for growing a more durable iteration of the high-efficiency perovskite crystal formula FAPbI₃ (formamidinium lead iodide). The new method, which involves growing the crystals on a nano-thin, 2-dimensional template, also improved the conversion efficiency of the solar cells.

“While solar cells without any 2D crystals degraded significantly after two days of generating electricity from sunlight in air, solar cells with 2D templates did not start degrading even after 20 days,” the school explained.

Twenty days before degradation does not sound particularly ambitious in terms of commercial applications. However, the research team also added an encapsulation layer to improve durability. The resulting solar cells achieved “timescales approaching commercial relevance,” as described by Rice.

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Photo (cropped): New tandem solar cells made with perovskite and silicon are coming into the market, promising lower costs and higher solar conversion efficiencies (courtesy of Oxford PV).