The big change in recent years is the explosion of perovskite-family cell materials. There's a huge variety of perovskite materials offering tunable band gaps and they can be processed at low temperature, so they can be used as top cells over silicon. That promises a big cost reduction from conventional multijunction cells built with III-V compound semiconductors on germanium [1].
There are a few problems so far:
- The perovskite materials containing organic moieties tend to be sensitive to degradation by moisture and/or oxygen. They need to demonstrate 20+ years of service life to match silicon.
- The purely inorganic materials like cesium lead iodide are more stable but have yet to attain high cell efficiency.
- There is no proven high-volume way to deposit the thin films of perovskite materials, which have different handling characteristics than anything previously used in solar manufacturing.
I would say there's a good chance of silicon/perovskite tandem cells taking off this decade but it's not yet a sure thing.
i'd say they need to demonstrate 50+ years of service life to match silicon, but at 10+ years they'd be marketable at conventional utility discount rates, and beyond 20 years the npv doesn't change noticeably
it'll sure be interesting to see what happens here, but it's going to be really tough to match silicon's cost per watt, much less beat it, unless you can dispense with the glass or something
while they are indeed rated for 20–25 years, as you know, in silicon panels most of the degradation happens in the first couple of years; additional degradation in the following 30–25 years is measurable but fairly minimal
as i understand it, panels are rated for 20 years not because they need to be replaced then but because 30 years ago nobody knew what would happen over that time, and also manufacturers didn't want to set themselves up for unlimited liability
usually it's more advantageous to add more panels than to replace the existing ones at that point, though rooftop installations are often an exception due to the extreme space limitations
i think if you sold a perovskite hybrid panel that cost half as much per watt as existing silicon panels, but degraded down to 70% of its rated capacity at 10 years and rapidly down to 50% after that, i think it would still sell in a lot of markets
Yes, high-efficiency cells have been around for a long time for cost-no-object applications, mainly space.
What's changing is commercialization. Two or three of the big Chinese manufacturers have pilot projects going for two-layer cells. Of the order of 10 MWe, that sort of size. (I can't remember which companies, sorry; it was a few weeks ago I read about this. Probably at least one of Jinko, JA Solar, or LONGi is in there, as well as one or two of the second tier.) Also in the West there are a few startups working on two-layer cells, either perovskite on silicon or perovskite on perovskite.
(Perovskites are more easily "tunable" in terms of which frequencies of light they absorb, apparently--that's one of their attractions.)
those are used almost entirely in space applications because they cost so much more per watt
is there some reason to expect that to change