This website made me reconsider if 99.9999% SLA and always online is really that important for lots of websites. I used to self-host my own server in my own apartment, but gave up on that after my internet provider had their first major outage that lasted almost a week. Also I didn’t want to worry about the fire hazard, or the server going down when I was traveling etc.
But a solar powered server seems interesting, if the batteries could be made fire safe.
Also, any non-trivial system has failure modes that are not binary. Like, if your convertible car has the roof stuck down you can drive it, but you will be sad if it rains. So, is the car “up” or not? Similarly, if your site has writes offline for a database upgrade, but reads work fine, is it “up”?
The concept is just advertising and something that makes sense to senior management, but provides no actual useful metrics.