For some reason that I don't understand, the IEA mostly reports the amount of capacity added to energy systems per year and the changes in that amount. So that

For some reason that I don't understand, the IEA mostly reports the amount of capacity added to energy systems per year and the changes in that amount. So that 50% number isn't the growth rate of solar PV energy capacity, it's the growth rate of the growth rate. OP is talking about the growth rate of the percentage of the system that is solar. It's the equivalent of if they identified something's velocity and you tried to contradict them by pointing to its acceleration.