Looking to upgrade airport meshed system

I currently have 3 airport express routers.  One is the main house router, a second is in a utility room wirelessly connected to the main and then it is connected to an ethernet cable that runs to my shop about 100 ft away that connects to my solar system which doesn't have wireless and needs an ethernet connection.  And then I connect to a third airport express via ethernet cable that provide wireless in the shop.

I want to upgrade to newer tech.

I'm assuming I will need 3 new wireless routers to accomplish the same.  Just curious what is the best solution.

Thanks