Price, of course. Prices are expressed in cents/kilowatt hour. Plan types include fixed rates and variable rates. Fixed rates offer consistency throughout the plan term, which can run from six to 36 months. Variable rates can change monthly - they're great when prices go down, but not-so-great when they don't. Finally, if you care about your carbon footprint, you may choose a plan sourced by solar or wind energy.
On the one hand, long-term, fixed-rate (contract) plans offer stability in pricing. If energy supply costs suddenly go up in your area, you won’t be left paying more than what you bargained for. You’ll have peace-of-mind. If you want to switch out of your contract before it ends with a lower cost plan, you’ll likely face a cancellation fee (early termination fee).
But in future, BNEF argues, the aim will be to secure as low-cost renewable power as possible and supplement that with “more expensive flexible capacity from demand response, storage and gas, and then importing the remaining needs from neighbouring grids. We are reaching the point in the story where power system regulation will have to be fundamentally rethought .”