That is a false comparison, because you're comparing a 'positive evolution' (yield of PV increases) with a 'negative evolution' (amount of horse manure produced

That is a false comparison, because you're comparing a 'positive evolution' (yield of PV increases) with a 'negative evolution' (amount of horse manure produced grows). What he's saying is that, even without radical breakthroughs, we will reach grid parity in a few years. Of course there may be a breakthrough in either PV or other tech, that will make it only better. What he's saying is that we've reached the point where we can generate renewable electricity. Now we only need to triple the output so that we can have our cars drive on it too, and that industry can run on solar power.