Any DC residents familiar with whole house TOU for EV's

[Anonymous]

Is it worth it? It seems like the peak power rate increased cost from 5.5 cents to 12.3 cents (kW) from noon to 8 pm is almost enough to offset any saving from off peak reduction in charging to 4 cents a kW. I only charge a couple of times a week, maybe 30kW per charge. I do it at night anyway, so yes I would fall into off peak charging, but the peak tariff for saving a bit more than a penny seems pretty stiff.

[Anonymous]

I decided that this was a standard PEPCO bait and switch for a modern EV. I am sure that if you are driving A LOT of EV miles per day, you can make this plan work for you. But for my particular uses, my daily bill is higher so no, not worth it.

First, I drive a modern EV and only have to charge it once or twice a week. I charge from about 50% to 80% (100% before a long road trip) and when I charge I charge at night because that makes sense. I plug the car in when I lock it up and the car takes over from there having itself charged when I am ready to leave. If I look at my PEPCO power useage I can see that those power draws typically happen from 3am to 6am and the car is taking on average around 33kW.

So right off the bat, I am charging at night 99% of the time when the grid has its most elasticity. I cannot remember anytime charging at home during what Pepco considers "peak useage" between 12 noon and 8 PM.

So with the STANDARD Pepco pricing scheme that anybody who lives in DC is using unless they have changed to the Whole House TOU plan, I am paying $0.05986/kWh. If I average under 3kW of useage per hour but use that as a planning factor, I use 72kW a day for a cost of $4.30 a day or $129 a month. (Purely kWh costs, not delivery and all of the other nonsense Pepco charges)

So now let's throw in charging session one day and charge the car with 33kW's. That day my household useage will go from 72kW to 105kW and now I am paying $6.29 for that day or about $2.00 more for THAT DAY of electrical useage.

Now go to the TOU plan. The eight hours a day of PEAK use between noon and 8 pm are not going to change. I average just under 3kW an hour and will still during the peak times. So if I do not change anything about my useage to drive down consumption during peak hours, my peak hours kW consumption is STILL going to be 24 kW's but I am now paying double what I was before for those kW's (new price is 0.10618/kWh). $2.55 for the eight hours of peak time consumption of 24 kWh's. On a non charging day, I have 16 hours of the day that now fall into OFF PEAK and I get an awesome Pepco break of a penny (new rate 0.04310/kWh) and my new OFF peak average for 48 kWh's is $2.07. So under the TOU pricing scheme my electrical useage for a non charging day is still 72 kWh, however, I am paying $4.62 a day or $138.56 a month.

So by using the TOU plan and NOT charging my daily home power cost has increased $.32 a day and $9.6 a month.

Now throw in a charge at the new rate saving a penny a kWh (33kW at the new rate of 0.04310/kWh is $1.43). Using the same method as above though we are now increasing the kWh's used during the 18 hour OFF PEAK time from 48kWh to 81kWh or a cost of $3.49. So on a charging day, my cost to the user is PEAK + OFF PEAK or $2.07 + $3.49 = $5.56 for a charging day. So on a charging day I save $.73.

So I would have to charge 14 times a month under the new TOU savings plan at a total of 463kWh's to start saving money. If you are a major commuter and charge that often, you can save money. If you are a daily charger, go for it. Maybe for PHEV owners this would work out better, however, the batter pack is so small I am not sure how. You would need to charge so much. And don't PHEV's just use free level 2 charging out in the wild.

Anyway, if Pepco really wanted to incentivize EV owners to charge off peak, they would simply reduce the amount charged off peak to EV owners. However, that is not their real goal. Their real goal is to make money and they have come up with a clever scheme and green washed it.

[Anonymous]

PP's very detailed post nailed why I opted not to switch to this plan.

We have solar panels on our home, too, so in addition to the silly math PP shows above, I realized TOU pricing would basically mean cloudy days would cost me more money.

I do about 99 percent of our charging at night, as well, both because that's more convenient and because I'm aware it's best for the system as a whole if our solar is sending excess into the grid during peak demand, not storing it in our car battery. But the only thing the TOU pricing seems like it would do is penalize EV owners for charging during peak demand -- not really reward you for charging at night.

[Anonymous]

Pepco actively penalizes solar users who also have EV's. At the end of the day Pepco's priority is their profit margin, not the grid or the environment.

[Anonymous]

Just got an EV and was shocked at the inane TOU pricing offered by Pepco.