By using 8-port patch panel (cost 11 euros / 16$) create 4 port POE injector. This is very simple /cheap project when it comes to POE injector.
This is done by wiring RJ45 pins (3,6,1,2) for networks to other patch panel port, and wiring power to Rj45 pins (8,7to negative DC & 5,4 to positive DC) to POE panel ports.
Full details at
See my other POE wiring and cheap ebay POE injectors posts