Yes, visit https://deq.mt.gov/
After each monthly billing cycle, any excess kilowatt-hours generated are placed into a bank on your electric account. Based on your energy usage, banked kilowatt-hours will automatically be deducted from your account up to April 1 for solar, and October 1 for wind. Your bank will reset on these dates.
For every kilowatt-hour you generate, a kilowatt-hour will be deducted from the usage on that meter. (retail rate exchange)
No, solar at the home or business ties directly into one meter and will only offset the usage of that meter.
A 15 KW solar system per meter is allowed.