I thought the same until I calculated that newer hardware consumes a few times less energy and for something running 24x7 that adds up quite a bit (I live in Europe, energy is quite expensive).

So my homelab equipment is just 5 years old and it will get replaced in 2-3 years with something even more power efficient.

Where in Europe?

Asking coz I just did a quick comparison and it seems to depend but for comparison I have a really old AMD Athlon "e" processor (like literally September 2009 is when it came out according to some quick Google search, tho I probably bought it a few months later than that but still ...) that runs at ~45W TDP. In idle conditions, it typically consumes around 10 to 15 watts (internet wisdom, not kill-a-watt-wisdom).

Some napkin math says it would cost me about 40 years worth of amortization to replace this at my current power rates for this system. So why would I replace it? And even with some EU countries' power rates we seem to be at 5-10 years amortization upon replacement. I've been running this motherboard, CPU + RAM combo for ~15 years now it seems, replacing only the hard drives every ~3 years. And the tower it's in is about 25 years old.

Oh I forgot, I think I had to buy two new CR2032 batteries during those years (CMOS battery).

Now granted, this processor can basically do "nothing" in comparison to a current system I might buy. But I also don't need more for what it does.

I guess you did the math but wouldn't it be more effective to spend the money on solar panels instead of replacing the computer hardware?

Energy is very cheap for data centers. have you ever looked up wholesale energy rates? It’s like a cent per kilowatt hour.