Electrify Everything: The Cost Of Solar Cells Has Nowhere To Go But Down, Down, Down

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Silicon solar cells deserve a pat on the back for ushering in the renewable energy revolution, but now it’s time for more efficient, less expensive technology to take the wheel. If you guessed that means perovskites, run right out and buy yourself a cigar. In the latest development, the UK firm Oxford PV has just announced that its new perovskite solar cells have set a world record for conversion efficiency. That sets the stage for broader access to photovoltaic technology, and that spells yet another headache for fossil energy stakeholders.

Yet Another Breakthrough For Low Cost Perovskite Solar Cells

For those of you new to the topic, perovskites are a class of synthetic materials based on the crystalline structure of the naturally occurring mineral perovskite. Natural perovskite was discovered in the 19th century, but its application to photovoltaic technology is a 21st century thing.

The first perovskite solar study was published in 2009. It touched off a firestorm of interest among solar researchers all over the world due to the potential for delivering high solar conversion efficiency with an inexpensive material, along with good prospects for low-cost, high-throughput manufacturing.

There being no such thing as a free lunch, initial attempts at fabricating perovskite solar cells ran into stability and durability problems. Those issues have been largely resolved along the way, one strategy being to combine a thin film of perovskite with some other, more reliable photovoltaic material.

That brings us to the latest record-breaking development. Oxford PV has popped up regularly on the CleanTechnica radar since 2013, when it spun out of the Henry Snaith group at Oxford University in the UK with a claim of 15.4% conversion efficiency for its perovskite solar cells.

That’s not even close to the efficiency of the best silicon solar cells on the market today, which clock in around the 25% mark on lab tests. However, it was good enough to bet the ranch on more perovskite R&D.

By 2014 the company was exploring the potential for a thin film of perovskites to boost the solar conversion efficiency of silicon, and by 2015 it was attracting the big bucks to support its plans for expanding its perovskite R&D efforts into other solar cells and even plain glass.

It looks like all that hard work has paid off. On Monday, Oxford PV announced  that the latest iteration of its silicon-plus-perovskite solar cells hit the 29.5% mark, as confirmed by the US Department of Energy’s National Renewable Energy Laboratory.

No Wait, It’s Another Really, Really Big Breakthrough For Perovskite Solar Cells

The new solar cell isn’t 100% perovskite, but it still adds up to considerable savings by cutting down on the amount of silicon needed to deliver the clean kilowatts. Silicon is more expensive than perovskite, so all else being equal, the new solar cell will cost far less than an all-silicon counterpart.

According to Oxford PV, the new solar cell will also generate 20% more power in residential rooftop applications than a comparable silicon solar cell, meaning that it could expand the rooftop solar market to smaller buildings with smaller roofs.

To look at it from another angle, Oxford PV calculates that 35 kilograms of perovskite can generate the same amount of power as 7 tons of silicon. That’s tons. Tons. Tons.

Wrap your head around that 7-ton figure, and what pops up on the perovskite radar is the reduced need for energy involved in procurement, shipping and manufacturing on the supply side, all on top of the renewable energy produced at the user end.

How Fast — And How Far — Can Solar Go?

Oxford PV aims to have its new solar cell ready for the market by 2022. That may seem like a long time to wait, but it’s a wink of the eye compared to the pace of progress in silicon technology.

Not to dump on silicon or anything, but it’s been a long haul getting to the 25% mark for silicon solar cell conversion efficiency. The first practical silicon solar cell was introduced in 1954 by Bell Labs with a 6% conversion efficiency, building on earlier silicon research conducted at Bell in the 1940’s.

Now compare that with the pace of improvement in perovskite solar cells over just the past 11 years.

If you’re thinking what we’re thinking, a new generation of inexpensive solar cells means that photovoltaic technology will soon be as commonplace and accessible as any other large household appliance, from a TV to an HVAC system and everything in between.

Solar access will also expand for households that can’t get their own rooftop solar panels because of financial obstacles, tenant-landlord relations, or technology issues such as too much shade.

Over here in the US, solar access is a hot topic for policy makers over at the Department of Energy, despite the fossil-friendly rhetoric of outgoing *President Donald J. Trump.

Last spring DOE re-upped an Obama era goal of bringing affordable community solar programs to every household — that’s every household — in the US by 2025. That includes unsticking the solar market for low- and middle-income households.

The new iteration of the DOE program is based on lessons learned from the “Solar in Your Community Challenge” issued by DOE’s National Renewable Energy Laboratory during Trump’s first year in office, and they have been hammering away at the shared solar market ever since. Just last October, DOE introduced a new angle involving affordable financing for shared solar projects.

But Wait, There’s More Solar On The Way

The low cost of perovskite solar cells is just one element in the coming photovoltaic revolution. Oxford PV is already looking forward to the development of a 100% perovskite solar cell, which opens up a whole new range of applications for photovoltaic technology.

How many? DOE’s National Renewable Energy Laboratory has championed the cause of perovskite PV technology from the start, so let’s have them explain it:

“… perovskite-based technology holds transformational potential for rapid terawatt-scale solar deployment. The basic materials properties have also sparked interest in using hybrid perovskite semiconductors in a broader class of energy applications that span traditional electronic and optical systems.”

NREL has been paying particular attention to halide perovskite systems, which can literally be painted or printed onto surfaces.

“The application space for this general class of systems includes low-power electronics, light emitters, detectors, and associated integrated-circuit systems for dynamic energy management with numerous applications,” the lab explains, adding that “the unique carrier cooling dynamics indicate that these systems may also be compelling for thermoelectric and associated energy-scavenging applications that cut across civilian and military energy needs.”

Incoming President Joe Biden will have a lot on his plate when he takes office on January 20, but it sure looks like he has a running start on a new, more powerful wave of PV tech.

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*Developing story.

Photo: Perovskite solar cells courtesy of Oxford PV.