Vermont Public Radio has an excellent piece (right here) about the benefits and complications that solar power is bringing to that state, and to the New England grid as some states such as Vermont and Massachusetts charge on the solar bandwagon and others, including New Hampshire, are less involved.
“It’s a really interesting push-pull,” Wright says. “Because when it’s hot and it’s sunny it’s nice to have less load to manage. But when you start to have those regional issues, and one state is doing a lot of [solar] generation and one’s not, and you start to set your transmission costs based on your load allocation, it gets really volatile. And I think in the future that might become worse. But it’s definitely something that no one has really talked about yet.”
Right now, peak power costs are the driving factor, monetarily at least:
To understand what happened, you have to understand how power companies pay for their transmission costs. These prices are set annually – and are pegged to how much the utility uses on that one time of the year when it draws the most electricity from the grid. Little swings in demand can make a big difference in transmission costs. “That swing for us could be $400,000 to $500,000 to $600,000, just between those two days,” Wright says.
So every power company pays obsessive attention to that day of peak use; they even ask customers to turn off appliances like dryers or dishwashers until the peak has passed. Solar systems can help offset that peak demand in the summer. But they did not help Vermont Electric during that hot week in August. The problem was it was sunny in Massachusetts, where solar arrays all over the state helped reduce the strain on the grid. But in northern Vermont, clouds and rain reduced the solar output. So Massachusetts will save on transmission costs for the year, while Vermont will not.