OK, I finally have some code that adds ToU tags to Sense hourly export files, then aggregates the data into daily and billing period summaries, so I can compare against my real PG&E billing data. The fun part is I can also pull out solar and see how much solar is saving me, though I might likely be using a different rate schedule if I didn’t have solar.
Here’s a view on the kWh comparison between my PG&E bills and Sense aggregation.
As I examined in the thread below, my Sense is about 1% optimistic (lower) than my PG&E numbers on an hourly basis, plus I had fair number of network related dropouts WRT Sense, especially within May and June, so this data appears to square with my hourly investigations.
And here’s a view of how much solar has saved me over the past year. Roughly 2K per year on a 15.5K total investment back in 2012. Sure there are better deals today.
Here’s the actual code and side files to make it all work. Just change all the read_csv’s to point to where you locate your Sense hourly output data and the associated side files.
Thanks… Definitely doubled up on the holidays file. Have replaced with the real billing cycle file.
BTW - Have also tested using my PGE hourly data and it it comes out exactly matching my billing kWh, so I’m pretty confident that there aren’t any 1 hour off or 1 day offset kinds of issues that often occur with interval computations like this.
Here’s another view on costs… Time of Use EV-A schedule vs. the traditional E-1 residential schedule with tiering. It’s an eye chart but kind of shows all the computations that goes into each type of billing.
For my house the E-1 baseline is 10.1kWh/day during summer and 10.9kWh/day in winter. The three tiered costs per kWh today are: Tier 1 - $0.21536/kWh, Tier 2 - $0.28478/kWh, Tier 3 - 0.44095/kWh. The bottom line, I save about 750/year by using TOU and moving most of my car charging to off-peak.
And just for fun, I did a tiered estimate without solar (removed solar offset from the calculation). The combination of my solar investment and TOU saves me over 3,200$ / year on a 15.5K total investment.
