I can see that critical thinking isn’t your strong suit, but I’m willing to comment it out with you instead of just down voting.

If the price of solar is already the lowest -and still dropping- then how is the most expensive option that takes about a decade to implement a better option for right now? This apparent point of diminishing returns is only beginning to manifest in even lower prices than this 2019 chart. And this diminishing returns point is only in the cost of the panels dropping; they are still getting better in technology and improving efficiency while maintaining low prices. If your argument is “solar can’t continue on this trend forever” -no one expects anything to consistently drop almost 90% every decade. Of course it will level out. And when it does, it will STILL be the cheapest option.

Yes and no, the progress of solar array technology continues unabated, with multiple areas of research that are beginning to reach commercial applications. Module conversion efficiencies now are in the 20% range, but heterojunction cells, or Gallium Arsenide, or Perovskites, or any number of other possible advancements could easily put efficiencies up into the 30% range.

That being said, the price of the solar modules themselves has already shunk to a small piece of the cost to build a solar array, with the bulk of the costs now being the support structures, wiring, electrical equipment, labor, development, etc. And those costs aren’t going to decline, they’d still be there even if the solar panels themselves were free, so they effectively set a floor to the cost reductions we’re seeing.