I initially thought the same, but then I did the maths (sloppily). Reasons for repowering would be that newer modules are more efficient for reasons other than

I initially thought the same, but then I did the maths (sloppily). Reasons for repowering would be that newer modules are more efficient for reasons other than age (in the case of the Swiss array, new modules would be over twice as efficient) and that the modules are a fraction of the cost of the array - modules are very cheap now. In a very naive calculation, a module pays for itself in less than a year https://ourworldindata.org/grapher/solar-pv-prices https://ourworldindata.org/grapher/solar-pv-prices (assumptions: $0.26 / kWh, more than 1000 full-power hours in a year). A new module (again naively, without installation or capital costs) replacing a 20% degraded one would then pay for itself in about five years. So, I guess we are now in a situation where solar modules are almost free - there are now other problems to be solved and they seem difficult, storage especially...