It’s a cool idea, but has not worked well in practice. The plant referenced in the 2016 article you linked (Crescent Dunes) stopped operation in 2019 due to performance and cost issues. It appears to have restarted after the original owner filed for bankruptcy and sold the asset, but at a lower capacity.

https://en.m.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project

It looks like it regularly goes on sale that cheap on Amazon, at least in my region:

https://camelcamelcamel.com/product/B0BVFS94J5

I guess Freud was right

The most intuitive analogy to federation to me is email. You may have an account with one provider (gmail.com in the example of email, or lemmy.world in the example of Lemmy) but you can send emails to other providers (email example) or post messages to other instances (Lemmy).

Just like with email providers, a Lemmy instance may decide not to allow communication with another instance - this is “defederation.” Instances that allow communication are “federated.”

Just like email, you don’t normally need to worry much about whether you are on the same instance as a particular community or user - it just works.

This is a simplification, but for me is a good working model.