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Why the first-year forecast is a range

For SCE homes, bills tell how much the home used each month but not at which hours. Cali-Graf calculates the year for many hourly patterns that all match the bills, shows the middle one in the tiles, and the likely range — P20 to P80 — under the bills.

Two homes with the same bills can use power at different hours — one runs the dishwasher at noon, the other at 8 PM. Under SCE’s solar billing, that changes the bill. LADWP nets solar 1:1 over each billing period, so the hour matters little and no range is shown.

Where the range comes from

Cali-Graf builds the home’s hourly usage from 30 similar homes, each fitted to the customer’s bills (see How the hourly usage profile is built). It calculates the bills for all 30. The tiles show the middle result; under the bills in All numbers you’ll see, for example, “likely $1,180–$1,420 (P20–P80)”: six in ten of the patterns fall inside it. With a Green Button file the hours are the home’s own, so there’s one result and no range.

How to make it narrower

  • A Green Button file gives the home’s real hours, so the range goes away — the most exact input.
  • SCE time-of-use kWh from the bills pin down the peak and off-peak share — see Enter time-of-use kWh from SCE bills.

What to tell the customer

The proposal shows the middle forecast. If the range is wide, say so: real bills will land somewhere in it, depending on how the household actually uses power.

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