How much is a kWh in your parts? Noise, ambient temperature? You can buy very decent refurbished Lenovo tiny PCs with some 16 GB RAM and 6 cores and half a TB SSD which will run Proxmox and are low power and noise. You can go multi-node Proxmox later if you want to expand. k8s and related are also an option.

DIY few kWp solar payback is about 2 years.

In Germany consumer power is something like 0.4 EUR/kWh, so economics of running power-hungry hardware might be different. Solar PV might change the equation once again.

It sound impressive, until you read it’s Las Vegas. In places like Germany you have several weeks per year with neither enough sun nor wind. With backup power like gas turbines which run few weeks per year you have to subsidize the operators. And if you want run them on green hydrogen, massively overbuild the renewable capacity so that you can fill up gas storage during summertime.

Gmail is way more reliable than anything I could self-host. It’s a huge pile of unsorted junk that is only usable with search.