Evaluate tariff options

Sense has allowed me to reduce my electricity consumption, identify electrical issues, and reduce my electricity cost. E.g:

  1. Replace all incandescent and halogen bulbs with LED.
  2. Replace old pool pump with an efficient variable speed pump.
  3. Identify a failing AC compressor capacitor.
  4. Help perform data analysis of PG&E's (my electric company in California) set of residential tariff options.
  5. Influenced behavioral changes; make use of major appliances during off-peak hours, and to pre-cool my house (run AC) earlier when the sun is still allowing my solar system to generate sufficient power and/or during non-"peak" hours.
  6. My next project is to hunt down my 484W Always On vampires.
I want to discuss item (4) here. You should be aware of the different tariff options available to you, and determine which is financially the best for you. PG&E recently automatically transitioned folks who were on their EV-A tariff to their newish EV2-A tariff. (Both these tariffs are only available for residential customers who have an electric car; they have other time-of-use, TOU, tariffs too.) If you have solar and net metering, a tariff like EV2-A is a terrible option, as 2-4PM is no longer a "peak" period; 2-4PM is an important 2 hour window when NEM credits accumulate from solar generation when you want high rates. Additionally, EV2-A shortens the "summer" rates by 2 months; May and November are treated as "winter" where the "peak" period rates are much less; those months have tons of solar generation still, but little consumption (AC not needed, pool pumps don't need to run as long) and are great months to have high rates for NEM credits to be accumulated.

If you've had your solar system installed in the last 5 years, you can request to be kept on the EV-A tariff and benefit from its much more solar consumer friendly rate plan, but you have to contact PG&E to get grandfathered.

Regardless, look into your local electric company's tariff options to see which is best for your consumption and generation profiles. I expect many electrical utilities will continue to make their tariffs more hostile to solar customers (and more beneficial to their grid...which I understand), even when they keep net-metering fundamentals, and that we need to be more vigilant to determine the best tariff option.

One of these days, I hope Sense will support TOU (and tiered) electricity cost mechanisms, so that its electricity cost feature is actually useful. In the meantime, exporting Sense consumption and generation data, and doing offline data analysis, in Excel for example, is an option.

Indeed, it seems inevitable that Utilities will be very dynamic in their dealings with solar customers. As much as possible, having household energy storage beyond an EV is perhaps the only way to smooth out those dynamic$.

I can imagine Powerwalls charging EVs, that scenario is inherently worrisome … I’m rooting for small scale flywheels.

BTW, I recently found this Syonyk guy’s blogs, and found these 2 extremely informative on how the grid works. They are a long read, but worth the read:


Good post, and Sense’s data export feature makes it easy to find out which rate schedule makes the most sense for a given household. I was fortunate enough to be able to make this analysis a few years ago using my utility’s smart meter data, but the Sense data download interface is much easier to use.

In my case, the new optional EV rate schedule that incentivized off-peak charging would have increased my overall rate even if I shifted my charging to overnight hours, so I stuck with the standard non-TOU schedule.

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For me, the move to EV2-A should be beneficial during the winter, but more painful in the summer (cooling) season, and neutral for car charging for me, since I’m pretty much only charging during the off-peak for both EV-A and EV2-A. The only change we need to make is moving any drying into the morning. But I can understand PG&E making the change since they have to deal with the infamous duck curve.

Here’s to hoping the PG&E installs some storage or incents us to do so (I guess they already are).

The data that can be downloaded from the smart meter doesn’t break out the solar generation from the consumption, whereas sense keeps them separate. In another post recently (https://community.sense.com/t/need-a-little-help-understanding-the-data-export-from-the-web/8422/3) I shared my technique for analyzing data downloaded from Sense, though I stopped short of sharing the next step of modeling different TOU rate plans.

PG&E will do analysis for you on their website that shows what the best tariff for your usage is, but they again only see net usage, and they don’t share how they do their calculations, and you can’t model “what if” scenarios. You can see, however, large differences is costs between the plans…an indication that you really ought to be smart about which rate plan to choose…the topic of this thread.

I did a standard PG&E E-1 vs. EV-A calculator, that looked at with and without solar using Sense exported data a while back. It’s in R, so not for everybody.


My conclusion was that the combination of my solar investment and TOU saves me over 3,200$ / year on my 15.5K investment back in 2012. I could change the R logic to the new EV2-A schedule to see the impact.