Many clay tile roofs on the traditional European houses are over 100 years old.
Below is a section which shows several types of roofs, the one on the left must be from the pre-war times.
Indeed, although there are many different types of construction around. Most types of construction last a long time, especially when they are protected from direct sun radiation by e.g. Photo Voltaic (solar) panels. One does need to be careful with the mounting points of the PV panels on the traditional roof surface, those will become the critical spots to monitor.
In general, the roofs here outlive the expected useful life of solar panels, so Alan K's scare tactics are just to justify inaction.
In fact, the roof covering of the apartment complex I'm living in, was replaced (as a precautionary matter) some 15(?) years ago (they were from the '70s, so some 30 years old at the time.
And in addition to financially breaking even in something like 7-10 years, out of the 20 or so years that PV solar panels are expected to last (with warrantied efficiency), one immediately starts contributing one's bit to the reduction of CO2 emissions (and starts saving money after break-even). And with improving PV-panel quality/efficiency and rising energy taxes, the break-even period is likely to get even shorter, to the point that the government is getting worried about that steady stream of income.
And NO, there are no Diesel-fueled generators required to cover for the times with low solar irradiation. The
existing power plants just run at a reduced output level (or some of them are decommisioned/retired early), thus immediately polluting less. In (economically justified) time, even those will be replaced by (probably) Wind energy farms (in my case probably most of them at sea), or by Geothermal power generation (which provides direct heat, additionally converts water to steam for turbines, and produces Hydrogen through hydrolysis with the excess of energy).
Cheers,
Bart