Well, I think of an investment as something to make money on over time, the faster as possible.
I don't make money on a car but it sure is very convenient to have. Now, some cars costs less to buy or operate over time.
Yes, a Tesla or other electric cars energy cost to use is less than petrol and perhaps overall maintenance is also less. But, will I break even on this investment over time or make money?
Solar can be a good investment. I think I will have saved the cost of it by March of next year and make some over the years ahead. But, I will not sell it in 10 or 20 years to get my rewards back.
It is like using LEDs instead of the incandescent bulbs. Need light and it costs less but will get replaced if needed, not cashed out to reinvest.
Maybe it is a relative term what is considered an investment or a needed convenience that costs less to have.