Savings over 25 years
The 25-year forecast adds up yearly bills with and without solar as rates rise and panels age. Bill savings, 25 years counts bills only; 25-year savings in the price tile also subtracts what the customer pays for the system.
Solar is a 25-year purchase, so the customer wants to know what it’s worth over that time — not just next year.
How it’s built
- Year 1 is the result you see — bills before and after solar for the first year.
- Each later year, utility rates rise by the rate increase — 3.4% a year unless you changed it.
- The panels make a little less each year, at the degradation rate from their datasheet. The line under the chart names it.
The rate increase can be changed right on the 25 years tab: press Edit next to Utility rates rise, type a number and press Apply. More: Rate growth and panel degradation.
Two different 25-year numbers
| Number | What it counts |
|---|---|
| Bill savings, 25 years | On the 25 years tab: bills without solar minus bills with solar. The system price isn’t in it. |
| 25-year savings | In the price tile: the bill savings minus the system price, or minus all loan payments. This is the number on the proposal cover — net savings. |
Without solar and With solar on the same tab are the total paid to the utility over 25 years.
Keep it honest
The 25-year number grows fast with the rate increase. Explain to the customer what you assumed, and that future rates and weather will differ.
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