"Proves". Your threshold of proof is exceptionally low. Skepticism should run both ways.
Why PV cells? Let me help. It was discovered early on that the detonation of a hydrous metal by a low voltage, high current electrical pulse yielded energy that was overwhelmingly photonic, rather than kinetic. An explosion of high energy UV and soft X-ray light. If it were somehow possible to have PVs that 1) could harvest such high energy light, and 2) somehow stayed clear of vapour deposit, then no dome would have been necessary.
But alas, the dome had to be introduced. It meant the high energy light would be down converted, greatly reducing the efficiency of light energy harvesting, since so much of blackbody radiation is infrared heat.
But the main fact remains: tremendous energy is released with the SunCell. How to harvest that energy is a matter of practicality for the particular application, and there will be many applications. PVs are a technology that has evolved considerably over the years and represents an elegant, relatively compact solution. But it is also expensive (for concentrated PV cells) and energy wasteful.
Tradeoffs all around. That's life.