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Windy_Skies · July 10, 2023, 9:40am

Solar power cells have raced past the key milestone of 30% energy efficiency, after innovations by multiple research groups around the world. The feat makes this a “revolutionary” year, according to one expert, and could accelerate the rollout of solar power.

Today’s solar panels use silicon-based cells but are rapidly approaching their maximum conversion of sunlight to electricity of 29%. At the same time, the installation rate of solar power needs to increase tenfold in order to tackle the climate crisis, according to scientists.

The breakthrough is adding a layer of perovskite, another semiconductor, on top of the silicon layer. This captures blue light from the visible spectrum, while the silicon captures red light, boosting the total light captured overall. With more energy absorbed per cell, the cost of solar electricity is even cheaper, and deployment can proceed faster to help keep global heating under control.

The perovskite-silicon “tandem” cells have been under research for about a decade, but recent technical improvements have now pushed them past the 30% milestone. Experts said that if the scaling-up of production of the tandem cells proceeds smoothly, they could be commercially available within five years, about the same time silicon-only cells reach their maximum efficiency.

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https://www.reddit.com/r/technology/comments/14srude/revolutionary_solar_power_cell_innovations_break/

Small gripe: Perovskite solar cells and tandem perovskites don’t use the mineral perovskite, as the article incorrectly state. They use materials that have the perovskite crystal structure, and typically use lead and halides. There’ve been attempts to make unleaded versions, but they have lower efficiency.

Plus, they degrade much faster than silicon cells, lasting a max of a few years. Couple this with the lead, and there’s some major concerns.

If you’re interested in this sort of thing, here’s a link to the NREL’s tracker for highest efficiencies of different types of cells. Highest are approaching 50%, but honestly the manufacturing techniques aren’t there for mass production of anything but silicon. This might be overcome with government and private entities putting a lot of money into research, but most use exotic materials. Silicon isn’t great, but it’s what we’ve got and there’s a reason it’s been the dominant type of cell for a while now. The research is still invaluable and should be continued, and reporting on it is appreciated.

This captures blue light from the visible spectrum, while the silicon captures red light, boosting the total light captured overall.

The problem with silicon isn’t the amount of light captured, it’s the amount of energy per photon: it depends on the so called “bandgap” of the material, which is the difference in energy between the base and the excited state of an electron. For silicon, that is 1.1 eV, which corresponds to the energy of a photon somewhere in the near infrared. Silicon can absorb higher energy photons, but it can only ever convert these 1.1 eV into useful energy, the rest is converted into heat. This means that silicon has a theoretical limit of just below 30% conversion efficiency, if it absorbs all the photons from near infrared to UV.

Multi-Junction solar panels improve on that by using higher energy bandgap materials on top of the silicon. So instead of getting only 1.1 eV from every single photon, you might now be able to get 2.5 eV from everything blue and below in addition to that.

Silicon solar panels are made of aluminum, glass, sometimes plastic, silicon, and copper, in that order. None of those are rare, and all of them are recyclable.

In particular, new solar silicon comes from quartz sand, which requires a lot of energy to separate the silicon from. Recycling old solar cells can skip that step, as they are purer than what comes out of the reduction furnace. It is just very few solar panels have reached end-of-life yet, so recycling is barely needed.

Wind turbines are mainly steel and plastic (for the blades).

Lithium is more common than copper, but we didn’t need much of it until recently. Development of new mines is underway, such as Thacker Pass in northern Nevada.

The first commercial iron-air battery factory started construction recently. Iron is much cheaper than lithium, but also heavier. So they will be used for stationary storage, leaving lithium for mobile uses.