[tedivm]

New Hampshire is on the national grid. If they have more power than they can use they simply sell it to Massachusetts so they can turn down some of their natural gas generation.

[smeej]

Massachusetts has basically the same weather at the same time. When demand plummets in NH, it also does in MA.

Somebody somewhere would still have to store the energy being produced overnight, which happens to be when nobody wants to use it.