It's hard in the beginning, because of research and development. After that, you got the technology side covered, you got the processes side covered, all you need is to build and install.
Making the first mobile phones was hard. Making another million mobile phones today: not that hard. Especially if you make a million more of an established model.
No, that's not how it works. Every growth process has limits. Solar has much more limits than mobile phones: land, resources (phones are tiny compared to solar panels), labour (not just production, but also placing the panels and maintaining them)... I reckon if we treat solar panels like mobile phones (throw away every 1.5 years) we won't get far...
Limits only matter when we at least start getting close to reaching those. There is enough land, labor and resources for lots of solar panels while most of us in the western world already have a smartphone and seem to replace them less often due to a seemingly slower tech cycle.
It's hard in the beginning, because of research and development. After that, you got the technology side covered, you got the processes side covered, all you need is to build and install.
Making the first mobile phones was hard. Making another million mobile phones today: not that hard. Especially if you make a million more of an established model.