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(1) I'm not sure what you mean by 'desirable value for the lifetime of any house'. 25 years may be below the desirable lifetime for structural components of a house. But for appliances (which I'd consider solar panels closer too), 25-30 years is relatively long [0]. Even for the closely related structural-ish component of roofing material, 25-30 years is in the range [0]. Asphalt shingles (which are most common around me) are 15-30 years. There are longer lasting roofs, but they're on the same order of magnitude. Most of the residential solar payoff calculations I've seen (in the US) are in the 7-20 year range, which is less than 25-30 years.

[0]: https://www.mrappliance.com/expert-tips/appliance-life-guide...

[1]: https://www.bobvila.com/articles/how-long-does-a-roof-last/

discuss

PaulDavisThe1st|5 years ago

Spanish tile roofing will last at least 80 years (possibly requiring a relay depending on the climate and how good a job is done with the first laying). With reasonable care, and luck in avoiding damage from above (e.g. trees), tile roofs could last 300 years or more.

Slate varies depending on the region it comes from - Pennsylvania slate tends to suffer badly from freeze/thaw action, but some from New England can match the 200 year lifetime associated with Welsh slate. Similarly for stone.

It is absolutely the case that these materials are not widely used in US construction. But they have lifetimes that more closely match the expected life of even a moderately well-built stud frame house.

Metal roofing is rapidly gaining ground in some parts of the USA, and has a theoretical lifetime even beyond tile or slate. Unfortunately poor initial installs in many cases shortens the real-world life to something closer to high-end asphalt shingles.

The appliance/panel comparison strikes me as apt in some ways, but not in others. While removing/replacing roof-mounted solar might be approaching ease of replacement that is in the same ballpark as a typical stove, refridgerator, washing machine, water heater or furnace, it is necessarily more laborious and more dangerous work, and involves a component that to all effects and purposes is totally passive.

I wasn't commenting on the payoff time, but on the notion that we should be installing this relatively short-lived equipment everywhere we possibly can.