A second tank can be added on for additional solar water storage. 
This is necessary for gas water heater installations or for households where large draws of water are taken every day. 
The tank is plumbed as shown in the diagram. A bypass valve kit is available from FAFCO for this installation type. 
The bypass valve kit includes easy to install flexible hoses and a bypass valve that simplifies plumbing. 
This easy to use valve can completely isolate the solar tank for maintenance or in the event of an emergency. 
The cold water supply is connected to the solar storage tank and the outlet of the solar storage tank is connected
 to the inlet of the electric or gas water heater. Hot water is delivered to the household from the electric or gas water heater. 

Part # 730 - Hot Water Tanks are not included in kits