Welcome
This is a calculator for people who are PGE Customers and are interested in purchasing a powerwall and seeing if using it to power their home during "Peak" periods instead of the Grid can save them money in the long haul. For more details Checkout the GitHub Repo.
This site is Javascript (runs locally) so no data is sent to our servers or uploaded. I don't want it. But don't take my word for it, download and checkout the code yourself.
Lots of things can change, and I'm no expert just a hobbiest. Any information you get from this tool is used at your own risk. If you see something wrong file an issue
Grid Usage

To estimate year round ROI, you'll need 365 contiguous days of grid usage data. This can be retrieved and uploaded from your service provider, simulated, or estimated based off partial data. To best estimate ROI, it is likely best to upload just the time periods for which your grid use was typical, and to use that data then to estimate the use for atypical periods in your data.

  • Go to PG&E website, login and open "Energy Details"
  • Select the green button "Download my data"
  • Select radio button for "Export usage for a range of days" and select a period up to 365 days long that contains typical grid use for the given period.
  • Upload electric csv below
  • Repeat until you have uploaded all periods of typical use
CVS needs 3 columns:
  • Either:
    • DATE (YYYY-MM-DD) and START TIME (HH:mm)
    • Or a single date time: DATETIME (YYYY-MM-DD HH:mm)
  • Either:
    • kW (kW)
    • W (W)
Download Date and Time Template
Download Datetime Template

Depending on your setup, enphase can export a usage for every 15 minutes, the important column in this place is the raw grid usage without factoring in production (grid usage vs home usage).

  • Login to enphase
  • Go to reports
  • Select monthly net energy and run report for each of the last 12 months
  • Upload