Formula
The avoided bill is production times price:
annual value = annual kWh × price per kWh
Rounded to the nearest cent. The payback page divides a system cost by savings. This page stops at the yearly value.
Assumptions
- Every kilowatt-hour offsets a purchase at the same rate.
- Export and import prices are the same number you type.
- No standing charge is removed.
Worked example
8,000 kWh at $0.15 per kWh is worth $1,200.00 in a year.
Input definitions
- Annual production
- Kilowatt-hours the array is expected to produce. You type it.
- Price per kWh
- The retail rate those kilowatt-hours would have cost.
Limitations
This is a planning estimate. The rate, sun hours, and losses are numbers you type. It is not a utility bill, a solar design, or a room-by-room load calculation.
Questions
Is this the payback?
No. Take this yearly value, or your own savings figure, to the solar payback page and divide it into the installed cost.
What if exported power is paid less?
Type the blended rate you want to use. This page has one price.