> Well it happened in the solar module market[1]. What is "it" that happened? If you are talking about sustained exponential cost reductions over a period of d

> Well it happened in the solar module market[1]. What is "it" that happened? If you are talking about sustained exponential cost reductions over a period of decades, like Moore's law, then maybe it did happen from a very high starting cost, but it won't continue. Any market can undergo a rapid reduction in prices over a short period of time, as a product increases in adoption by one or more orders of magnitude. You could fit an exponential curve to that growth, but ... it will almost never be sustained. The future is what we are talking about here. Let's take solar modules as an example. From something like [1] prices have dropped from about $4.00/watt to $0.30/watt in 10 years. So that's a price drop of about 23% per year (each year is 0.77 the price of the previous). So today, at 30 cents/watt a 300W panel (the big ones you see on houses) is about $90. If that is really a sustained exponential drop, those same panels will be $6.75 in 10 years. Possible? Yes. That said, I don't think you can find almost anything that big and heavy almost anywhere for $6.75. Maybe bricks or gravel or something, I'm not sure. 10 years later, those same panels will cost 50 cents. Possible? No way. You aren't going to ship a 300W panel anywhere for 50 cents. You aren't going to have space in your warehouse for something that big for 50 cents. You aren't going to be able to buy even the basic raw materials like glass and aluminum for 50 cents. There's a common theme here: for something to scale exponentially, at a fixed size, every part of the process has to scale exponentially. The cost of shipping was irrelevant when the panels were $1,000, but it becomes pretty important when you are trying to ship something that weighs 100 lbs across the world or even a country and sell it for less than a dollar. The basic raw materials are a pittance with $500 panels, but they dominate the cost if you are trying to sell them for 50 cents. The only way this exponential scaling works is if you can make something roughly the same size exponentially more efficient. That's that happened with CPUs. The CPU itself was more or less the same size for decades. They made them in similar fabs. There were some "traditional" efficiencies of scales thrown in, like moving from 200mm wafers to 300mm wafers, but the only thing that allowed exponential improvement was that the chips themselves became a million times more efficient without increasing in size or (mostly) the consumption of any raw material. CPUs didn't scale up a million times by building a giant fab the size of a country, and using wafers miles across and mining silicon from the moon, which would be how a traditional process would scale up: they scaled up by becoming internally a million times more efficient. Solar cells don't have that type of scaling available to them. There are hard limits on the efficiency (which is already above 20%) based on the physics involved - but even without any reference to cell physics there is a hard limit at 100% which means the efficiency upside is at most a one time 4x gain from here. --- [1] https://commons.wikimedia.org/wiki/File:Price_history_of_silicon_PV_cells_since_1977.svg https://commons.wikimedia.org/wiki/File:Price_history_of_sil...