There are plenty of online guides that show you how to build your own Faraday cage. The Mission Darkness Revelation EMP Shield is one you can buy for larger items. It is a military-grade Faraday bag for EMP/CME protection. It can fit gas generators, solar panels, power tools, and other home appliances.
This Faraday bag is MIL-STD-188-125 certified. It is capable of blocking WiFi, Bluetooth, GPS, RFID, and cell signals when set up correctly. This EMP shield has 30″L x 24″W x 22″H space inside for your things. You can find out more about it here.