Model SIE4SOL-40 Interlock Kit fits Siemens 40 position panels having a 4-pole, vertical throw main breaker and approx. 1 1/4" vertical spacing from the bottom of the main breaker to the top of the gen breaker.
 
This interlock has two positions:
 
1.  The gen breaker is locked out and the main breaker AND/OR solar breakers may be turned on or off independently.
 
2.  The main AND solar breakers are BOTH locked out and the gen breaker may be turned ON or OFF.
 
The gen breaker must occupy the two TOP RIGHT breaker positions and the solar breaker must occupy the two BOTTOM LEFT breaker positions.