story
How big is the house?
.. and this was quite thoroughly calculated. I can tear down the house and build a new one, but apart from the waste of resources - building a new one will also cost minimum €200k - so I thought, why not 'oversize' PV, if it only costs €100k and can heat the house without improving on insulation?
To emphasize, this conclusion will likely not apply to the majority of people (especially here on HN) because as many have said here, parameters and contexts differ widely.
I'd have guessed that 200k to rip it down & build a new house that has great insulation - or even to just retrofit insulation and other upgrades to the existing building - would be expected to last longer before costing the same amount against to replace (and/or pricey maintenance/insurance of the more expensive PV, aircon etc.). And might therefore work out cheaper when looked at as a 50 year question rather than 1 year one?
I don't presume to know more than you, not only don't I know about your specific situation I also know very little about these subjects generally, I'm just curious.
.. it was mentioned somewhere here, too: For some, the best solution will be to focus on reducing energy consumption; for other, the better option will be to focus on increasing local energy production. And a combination of both might be best for most.