That’s a fair point for GP’s Heroku + Cloudflare deployment. The OP solar site is a better example of efficient static hosting as it is run on a lightweight server [1] and not fronted with Cloudflare. The reading at the bottom of the website indicates 2.70 W power usage at the moment and over two weeks uptime.

[1]: https://solar.lowtechmagazine.com/about.html#hardware