Foolishly reductionistic model: at the instant that solar becomes defacto cheaper, if everyone immediately changed, you'd need at least [total world power consumption / solar panel production rate] years to change over.
2022 world electricity consumption was about 25000 TWH. That envelope-backs to about 2800 GW if the sun is always directly overhead everywhere and there are no transmission losses.
In 2022, we installed about 228GW of solar panels. Assuming constant production (HAH!) that says it should take more than a decade to replace the existing demand. Which will of course stand still for us.
Apply whatever multiplication factors you like about what percentage of the year a given real solar cell will generate power; about how quickly folks are convinced to change; about the construction of projects which were planned before this price threshold was passed; about the impact of using grid power to do transportation work which was previously done by pumping dead dinosaurs...
The confounding factors abound. But that's an ignorant sideline answer to why. :)
A simple but useful back-of-the-envelope estimate would be 25%. Half of the day, there's no sun, so you have 50%; the other half, it increases gradually until the middle of the day, then decreases gradually until the sun sets. Simplifying this to a linear increase and decrease, if you plot it into a graph you'd have a pair of isosceles right triangles, which cover half of the area, so you have another 50% over that first 50%, and the end result is 25%.
(IIRC, the real result for the single-axis trackers you'd find on grid-scale power plants is something like 30%, showing how good that simple back-of-the-envelope estimate is.)
It’s dominant already in newly added capacity. It just takes a while, mostly due to permission processes taking long.
And limited grid capacity, which is also held back by environmental review and nimbys - at least in the western world.
Seems like a win win, people get cheaper energy all without force. Generally the market chooses the best product, which is why we replaced horses crapping all over our cities with cars. It wasn't legislation or some global consortium of governments that phased out the horse, it was a better product. What am I missing here?