As you say, technology has moved on so fast, that both PV panels and storage batteries are so much more efficient. It should be mandatory in building regs that any new building with a vaguely south-facing roof has to have a full PV array with batteries. Tesla even make PV cells that look exactly like roof tiles, so no issues with spoiling the street scene in pretty villages.
They're not mandatory but the company I work for install them on every house we build where feasible.
Its definitely what house builders should do.
It's a pity they've lowered/removed a lot of the financial incentives for installing them.

