[jussij]

> but that’s only if the energy prices don’t fall.

You also need to consider what happens if prices keep rising, because if that happens the investment is paid back sooner.

I can only speak for what I see happening here in Australia.

Energy prices in Australia have been rising rapidly for a very long time and for several reason and don't look like falling any time soon.

From here: https://finance.nine.com.au/personal-finance/residential-ene...

Residential prices increased 63 per cent since 2007 and the average household bill was about $1524 plus GST.

It is this very sharp rise in electricity price that has driven the boom in rooftop solar here in Australia.

At those prices rooftop becomes very attractive.