Probably the assumption is that you will upgrade the panels at radically reduced prices, re-using the wiring and support. Then, the cost is for insurance agains

Probably the assumption is that you will upgrade the panels at radically reduced prices, re-using the wiring and support. Then, the cost is for insurance against the site being no longer viable. And, probably, the cabling has high scrap value. The future of solar is in mixed use, where the land continues doing whatever it was already doing, just with added revenue on a very different schedule. This easiest on pasture, but offers most value on reservoirs and canals. In a rational market it would be impossible to get financing for single-use solar farms. Instead, ignorant investors love them, particularly when sited in the worst choice of place, deserts. (Deserts are lousy because they are hot and dusty, cutting both output and panel life, and typically far from users requiring transmission line construction. And, the land produces no other revenue, so must be secured whole.)