FYI: Seattle City Light new “time of day” rates – analysis

Just a public service data point here.

SCL has announced they’re going to offer (optional?) “time of day” (TOD) rates in the fall of 2025. Basically, what you pay for power will depend on when you use it; evening times (5pm-9pm) Mon-Sat will be the most expensive, nighttime (midnight-6am all days) will be super cheap, and everything else is basically middle tier.

Since I’m (a) a geek and (b) had too much time on my hands today, I went through the exercise of pulling down all my usage for the past 12 months, summing it up by hour, and putting it in a spreadsheet that compared what I paid with the current flat rates to what I would have paid with TOD rates.

Result: One big nothingburger. Flat vs TOD total costs would have been within $10, across my previous entire year’s usage (August 2024 – July 2025), with TOD being ever so slightly higher. (Note that that’s a $10 difference across an entire year’s worth of electric bills – not per month. So like $610 for the year, vs $600.)

Where I do think TOD would make a big difference is if you have an electric car that you can charge it during the midnight-6am period., or maybe work some kind of job such that you can take a big chunk of your household usage out of the peak time slot. (Example: you’re not ever home from 5pm-9pm, so you don’t use much winter electric heat then.) But for me, without any of those options….meh.