Hi,
PSE in WA of course don't currently charge time-of-day usage fees.
However, I still wanted to make sure I charge my vehicle at the best time of day so as to optimize grid and green energy usage. I thought it may be a good idea for other PSE EV customers to also be mindful of this, so that that PSE don't feel compelled to have to charge for time-of-day usage in order to handle the increasing demand for EV's, which sounds like they are considering. Charging at specific times will of course be easier for us after the 4.3 software update.
I contacted PSE about their actual recommended time-of-day, and here is the response I got from Patrick Leslie (in short - 11pm to 5am):
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Hi Deon,
Congratulations on your Tesla purchase! Thanks for your excellent question and for your concern about reducing impacts on the grid and the environment.
We don’t currently have a time of use rate because given the relatively small number of EVs on the system, the cost to implement outweighs the benefits. We anticipate that will change once we reach approximately 10,000 vehicles. We’re currently at about 1,500. We’re seeing about 1.1kW of peak-coincident load per EV. To put that in perspective, our system peaks at about 5,500,000 kW. Our system peaks daily in the early morning and mid-evening, and critical peak typically occurs in the 5-7 am timeframe on the coldest day of the year. In general, charging between 11p and 5a is the best to reduce grid impacts. But let me reiterate that our grid is robust and we hope that EVs are adopted widely. The benefits of increasing throughput during off-peaks hours great exceeds the cost to upgrade transformer and prepare the grid in other ways.
As for reducing your environmental impact, our energy mix varies greatly by the day, month, and season. It’s practically impossible to make a general rule as to the best time to charge. We have a large share of hydro generation, so during spring runoff our entire region can have surplus hydro for limited periods. During other times of the year, we may be using more “thermal” generation (fossil fired). Wind is a growing share of our mix, but it comes and goes as it pleases and we generally balance the variability with hydro. How we dispatch generators also depends on what’s happening in the electric markets as far away as California. In general, our coal plant runs baseload, so your EV will not affect the dispatch of that plant. Most of the generation “on the margin” is hydro and natural gas, therefore if you are charging during peak periods, the additional load from charging your vehicle will likely come from a simple or combined cycle natural gas generators, or from shifting hydro generation around. I apologize if this isn’t clear, but there’s no cut-and-dry answer.
If you wish, you could sign up for our Green Power program, which supports local green power projects in the Northwest.
Thanks for your interest,
Patrick
PSE in WA of course don't currently charge time-of-day usage fees.
However, I still wanted to make sure I charge my vehicle at the best time of day so as to optimize grid and green energy usage. I thought it may be a good idea for other PSE EV customers to also be mindful of this, so that that PSE don't feel compelled to have to charge for time-of-day usage in order to handle the increasing demand for EV's, which sounds like they are considering. Charging at specific times will of course be easier for us after the 4.3 software update.
I contacted PSE about their actual recommended time-of-day, and here is the response I got from Patrick Leslie (in short - 11pm to 5am):
-----------
Hi Deon,
Congratulations on your Tesla purchase! Thanks for your excellent question and for your concern about reducing impacts on the grid and the environment.
We don’t currently have a time of use rate because given the relatively small number of EVs on the system, the cost to implement outweighs the benefits. We anticipate that will change once we reach approximately 10,000 vehicles. We’re currently at about 1,500. We’re seeing about 1.1kW of peak-coincident load per EV. To put that in perspective, our system peaks at about 5,500,000 kW. Our system peaks daily in the early morning and mid-evening, and critical peak typically occurs in the 5-7 am timeframe on the coldest day of the year. In general, charging between 11p and 5a is the best to reduce grid impacts. But let me reiterate that our grid is robust and we hope that EVs are adopted widely. The benefits of increasing throughput during off-peaks hours great exceeds the cost to upgrade transformer and prepare the grid in other ways.
As for reducing your environmental impact, our energy mix varies greatly by the day, month, and season. It’s practically impossible to make a general rule as to the best time to charge. We have a large share of hydro generation, so during spring runoff our entire region can have surplus hydro for limited periods. During other times of the year, we may be using more “thermal” generation (fossil fired). Wind is a growing share of our mix, but it comes and goes as it pleases and we generally balance the variability with hydro. How we dispatch generators also depends on what’s happening in the electric markets as far away as California. In general, our coal plant runs baseload, so your EV will not affect the dispatch of that plant. Most of the generation “on the margin” is hydro and natural gas, therefore if you are charging during peak periods, the additional load from charging your vehicle will likely come from a simple or combined cycle natural gas generators, or from shifting hydro generation around. I apologize if this isn’t clear, but there’s no cut-and-dry answer.
If you wish, you could sign up for our Green Power program, which supports local green power projects in the Northwest.
Thanks for your interest,
Patrick
