Hard on the heels of last week’s news that material scientists had developed a new material capable of keeping roofs cooler than the air around them, came word that researchers are busy developing a material called perovskite that could result in cheaper, more efficient solar photovoltaic cells.
Perovskite itself isn’t news. Scientists have known that it occurs naturally, but can also be easily produced in the lab. It’s plentiful and cheap.
In fact, they made the first perovskite-based solar cell almost a decade ago. But now they are working on combining the material with silicon to make what they’re calling a tandem cell that is more efficient than the silicon-based cells that now have 90 per cent of the global market.
That’s an impressive market share, especially since the performance of silicon cells hasn’t improved significantly over the last 15 years. In that time, efficiency has barely budged, edging up to 25.6 per cent from 25 per cent. The dramatic price drop in the same period is due to improvements in the manufacturing process.
Now we hear that perovskite can be stacked atop a silicon solar cell and greatly improve the cell’s over-all efficiency. Researchers now think they can achieve something around 30 per cent. That would mean that of all the solar energy the cell is exposed to, it would convert 30 per cent to electricity.
But there are development problems surrounding perovskite. While they can be solved with time, the price of conventional cells continues to drop. That could mean that by the time perovskite cells reach the starting line, the race might already have been lost.
There’s another factor involved here, and it has nothing to do with conversion rates or silicon or perovskite. It involves batteries.
A result of the drive to develop new technologies in the clean energy industry is that development of better batteries has lagged. That’s why people can shrug off solar power. The sun doesn’t always shine, so what do you do for light when the sun goes down?
Concentrating solar power is one answer, but it’s expensive because of the amount of land a CSP plant occupies. Another answer is to store surplus energy in batteries. But modern batteries still aren’t up to the challenge.
So there appears to be room in the field for Elon Musk, who was a co-founder of PayPal, which operates shuttle craft carrying supplies to the International Space Station; and Tesla, maker of high-end electric cars.
One of the things that has kept electric cars from capturing a larger share of the market is their range. How far can they travel before they need to stop for a re-charge?
Musk and his staff have been working on better batteries for the Tesla, and they may have made a breakthrough. Musk is optimistic enough that he is building a $5 billion battery factory on a piece of desert in Nevada. When it’s completed, it will supply batteries to Tesla. But, under the name Tesla Energy, it will also make a large home battery called a Powerwall.
Musk intends Powerwall home batteries to be paired with rooftop solar systems, giving home-owners clean, off-grid electricity.
Powerwalls will come in two sizes. A 7 kWh version will retail for $3,000. For $500 more their customers will get a 10 kWh system that will be able to keep an average-sized home running for a day. Of course, the batteries can be daisy-chained to create larger systems.
They’ll be available starting in a few months.
Here’s the thing. With better batteries, and with better solar cells (thanks to perovskite), solar energy stands to be a big player in the economy — far bigger than it could be without those two developments.
And if the sun doesn’t always shine? So what?
Korky Koroluk is an Ottawa-based freelance writer. Send comments to email@example.com.