Where is green mountain electric supply located? Green Mountain Electric Supply, Inc. a family owned and operated company servicing New England and New York is pleased to announce they will be relocating their Derry, NH location to a larger and more convenient building in Londonderry, NH. The address is located at 34 Londonderry Road Suite A2,How do i contact green mountain power? Email us directly at [email protected] , or use the form below. We will get back to you within two business days. Ask an energy advisor. Have questions? Give us a call!What companies are owned by green mountain energy? NRG Energy has been the parent organization which owns Green Mountain Energy since 2010. Retail electric companies in Texas including Reliant Energy, Stream Energy, Cirro Energy, and Discount Power are the sister companies of Green Mountain. Check out rates from Green Mountain and its sister companies at HomeEnergyClub.com.Is green mountain energy a tdsp? Green Mountain Energy is a REP and not a TDSP, so you will have to reach out your local area TDU to report a power outage: Green Mountain Energy got its start in Vermont in 1997. Of all electric companies in Texas offering renewable energy rates, Green Mountain was the first to solely focus on green energy for homes.