Will I still be a customer of my utility?

Yes - the only difference is that you will also be saving money as a retail customer of Glacial Energy. Your local utility owns the power lines that carry electricity to your business or institution, and they will continue to bill you "for the delivery" of electricity, at rates governed by the state. The actual electricity will be supplied  by Glacial Energy, an energy service company that constantly shops for the best wholesale prices to keep your costs down.