Questions for a privat setup of a mini cluster


I hope to get some good advice for my plan.

Currently I am running successfully several webapps for private use in docker containers since month.
Due to my wish to gain redundancy and sharing work load I am writing here.
My biggest issue to realize this project seems to be that my possible second server is most of the time off. It is just powering on if clients (evening) are online. But it is hosting some VM too.
If it is on I thought it could get sync data from server #1 and after that it could be available for helping sharing capacity.
I am really curious if there is a „easy“ reliable solution.