One thing I'd note is that while 15¢ is likely to be a very good price this winter, it might not remain a good price over the two-year rate period. Medford's community aggregation doesn't lock you in so you can switch to an alternative provider in the future if prices fall.

https://energyswitchma.gov/ (note it's a dot-gov domain)

There are other non-community-based energy providers you can choose from. The cheapest for me is 18¢, but it's a 36-month contract with a $150 cancellation fee. If you expect your basic rate to be 34¢ (which is what National Grid is raising their's to), that's almost half off. Let's say your winter electric usage was $100/mo last year from November-May (6 months). If that's going to become 3x more this winter ($300/mo) with basic service, it might only be $160/mo at 18¢. Each month you'd save $140 which would be $840. Let's say energy prices come down after those 6 months and basic service is back to 11¢. You cancel, pay the $150 cancellation fee, and you've saved $690 in the process.

Even if it was only $30, $48 vs $90 means saving $252 and even after a $150 cancellation fee you come out $102 ahead.

Note: that's how much you're spending on supply of electricity, not your whole electric bill. Your electric bill will include charges for the electric supply, the delivery, and being hooked up.

This is not advice, but it's something to look into. We don't know what Eversource is going to be setting their rates for when they reset in January (they're currently around 18¢).

EDIT: Brookline's graph shows how the price of electricity fluctuates: https://i0.wp.com/brooklinegreen.com/wp-content/uploads/2022/08/image-3.png

You can see how Eversource's rate has been lower than Brookline's rate at times. Brookline's rate is overall cheaper and you can see how Eversource's rate has spiked in 2022. However, you can also see that Eversource's rate never went above 14¢ in that 2017-2021 range so it seems likely that the basic service will go back down below 14¢ over the next couple years - assuming that Russia doesn't decide to wage a 3 year war with Ukraine, global warming doesn't boil us all in the interim, and COVID doesn't mutate into Terminator machines. But you never know, maybe power will remain above the 15¢ two-year rates being negotiated now for the whole time.

I still think it's a good deal, especially since you can opt out of the community aggregation at any time (non-community power supply might involve a termination fee). I just think it's also a realistic price based on what people are guessing power prices might be over the next couple years.

I'd also note that while Brookline's pricing is a cost savings over Eversource's rates, it's usually not that much of a savings. Around 11.1 and 11.6 for Brookline vs 10.7/12.9/11.4/13.6/10.9/12.5/9.9/11.8/10.8 for Eversource - before Eversource skyrocketed in 2022. Overall, it's a good deal, but it's not usually an incredible deal. Power prices are just going crazypants this winter.