Green Mountain Power (GMP) is living up to its name. The utility is in the midst of installing a 2,000 unit distributed virtual power plant that represents a total of 10 MW / 27 MWh of Tesla Powerwalls in customer homes. The battery systems installed to date under that plan, which is only 1/4 of the way complete, and two other energy storage systems have already saved the state half a million in demand charges this summer. On a state level, Vermont is one of four states where solar represents more than 10% of in-state electricity generation.
Much of that solar is on the homes and businesses of GMP customers, as revealed in statistics published by the utility last week. As of the end of July 2018, GMP noted that it has signed more than 150 MW of net metering agreements with distributed solar power systems. This value is up 1500% since late 2012 when it hit ~10 MW. It took about a year and a quarter to double to 20 MW, then it shot up in a year to 40 MW. The 80 MW doubling took about 21 months, and it looks like the 160 MW doubling will occur in about two years and three months.
This volume doesn’t include utility owned solar+storage facilities, such as those that came online in Panton and Stafford. These plants are not net metered, and instead are part of a long-term power purchase agreement. However, 65% of all solar power within GMP’s coverage area is net metered, and with the 80 MW of additional solar (including Panton and Stafford) under other arrangements, this totals 230 MW. As the utility services 265,000 customers – that means about 860 watts per account are online.