How to bill out electricity when you have solar

[Brent Silberbauer]

I am a property manager from Chico, CA.  I have a client who has solar panels that are paid for on his house.  There are two units, one is a main house and then a separate back house that will be rented out separately.  The way that the solar is set up is that at the end of the year there is either a credit or a bill depending on how much electricity the solar panels generated minus how much the units used. If the solar panels generated more electricity than was consumed by the two homes then there will be a credit, and if the inverse is true, then there will be a bill.  The two units are not separately metered.  So the question in this:  How to you bill for electricity?  Obviously, the thought is to just have it included in the rent, but the owner is afraid it will be abused and the bill will come at the end of the year and will be thousands of dollars.  We live in an area where the summers get over 100 degrees and you can rack up a large bill running the AC all the time.  Any help or suggestions on how to handle this would be appreciated.  Thank you BP!