What are the technological advancements that have made solar power so much more economically viable over the last decade or so?
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Okay so as an engineer I can tell you the main thing is just process control.
Most solar panels are made out of silicon, specifically extremely high purity silicon that can be “doped” with ions that cause what’s called a “band gap” between two layers that are doped differently. Essentially it causes one of the layers to want electrons more than the other, and sets up an aritificial situation where a photon could knock an electron from one to the other such that it can only get back to it’s desired place by going the long way around through a wire. (There’s some physics bullshittery here with quantum mechanics, but this is the very basic picture of it. This is generally how diodes work btw, and as a little piece of trivia, solar panels and leds are actually, in principle, the same technology with the current going the opposite direction).
*Well the big takaway is that to use silicon for solar panels they need to be pure enough that a few ions added changes their properties dramatically (compared to impurities).*
Well for years, researchers believed that the best way forward was to increase efficiency little bits at a time by using slightly different ions, tweaking compositions, adding layers, and increasing purity of the silicon used. Generally try to squeeze a little more juice out of each square centimeter
This was the wrong approach. It caused the price per square inch to skyrocket for very diminishing returns, and although these solar panels had their applications (most in space) they weren’t scalable.
The real breakthrough was when people figured out they could actually relax their purity standards (which were previously based on the purity standards of microprocessors) down significantly, and still produce solar panels that were reasonably efficient. See microprocessors (which we also make out of high purity silicon) break if they have even tiny variance in composition: a defect the size of a grain of sand would brick a unit. Solar panels care far less about these defects and generally work fine at several orders of magnitude less purity.
This is great because 99% pure silicon is a tiny fraction of the cost of 99.99% pure silicon (it has to go through far fewer refinement steps), and is much more cost efficient to mass produce with. Moreover, as we’vre grown our solar panel manufacturing processes, this 99% pure silicon (a made up number) has gotten even cheaper still, as engineers have come up with some clever ways to cut corners and make the processes even simpler and larger scale.
Hence, solar panels (and LEDs) have quickly become fairly cost effective per-unit in recent and only very slightly lower efficiency than the ones researchers were trying to squeeze more and more juice out of
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