I got my first electric bill of 2017 yesterday and was surprised to see that the rates had changed on January 1. I am in the Eversource Eastern MA territory (formerly NStar/Boston Edison) and recently started to use a Time of Use (TOU) rate service for charging my Tesla Model S. (I have a separate circuit used for car charging only.)
The good news is that the Eversource electric rates for delivery mostly dropped from 2016 to 2017. (All this discussion concerns the Eversource delivery charges; energy charges are separate and unaffected.) The standard residential rate dropped by 2.156 cents per kWh, a significant drop. But the TOU rates did not change as favorably. The winter peak rate dropped by only 0.46 cents/kWh and the summer peak rate dropped by 0.679 cents/kWh. But here is the kicker: The TOU off-peak rates actually rose a bit, by 0.223 cents/kWh, for both winter and summer.
The effect of these changes is that TOU rates are now less attractive because the savings relative to residential are now smaller, and the penalty for using peak rates is higher than before.
Previously, the winter off-peak rate saved the user 4.9 cents per kWh compared to residential, but now it saves only 2.5 cents per kWh. The summer off-peak savings has been cut in half, from 4.8 cents/kWh to 2.4 cents/kWh. And the penalty for using the summer peak period has grown by about a penny per kWh. Another way to look at it is that the number of kWh you must purchase to break even compared to residential rates is now about twice as high as it was before.
So, you can still save some money by using TOU rates, especially if you use a lot of energy and if you can confine your usage to the off-peak periods. But the savings are reduced, and the risk of undercutting the savings with peak usage is now higher. I have no insight into why the rate structure became less advantageous for TOU, but the drop in the residential rates may have left less margin for savings.
The good news is that the Eversource electric rates for delivery mostly dropped from 2016 to 2017. (All this discussion concerns the Eversource delivery charges; energy charges are separate and unaffected.) The standard residential rate dropped by 2.156 cents per kWh, a significant drop. But the TOU rates did not change as favorably. The winter peak rate dropped by only 0.46 cents/kWh and the summer peak rate dropped by 0.679 cents/kWh. But here is the kicker: The TOU off-peak rates actually rose a bit, by 0.223 cents/kWh, for both winter and summer.
The effect of these changes is that TOU rates are now less attractive because the savings relative to residential are now smaller, and the penalty for using peak rates is higher than before.
Previously, the winter off-peak rate saved the user 4.9 cents per kWh compared to residential, but now it saves only 2.5 cents per kWh. The summer off-peak savings has been cut in half, from 4.8 cents/kWh to 2.4 cents/kWh. And the penalty for using the summer peak period has grown by about a penny per kWh. Another way to look at it is that the number of kWh you must purchase to break even compared to residential rates is now about twice as high as it was before.
So, you can still save some money by using TOU rates, especially if you use a lot of energy and if you can confine your usage to the off-peak periods. But the savings are reduced, and the risk of undercutting the savings with peak usage is now higher. I have no insight into why the rate structure became less advantageous for TOU, but the drop in the residential rates may have left less margin for savings.
