Net Metering vs Net Billing Calculator
Two identical arrays on two identical houses can produce wildly different bills because of one line in a utility tariff: what you are paid for a kWh you send back. Full-retail net metering credits exports at the retail rate. Net…
What this estimate does
Two identical arrays on two identical houses can produce wildly different bills because of one line in a utility tariff: what you are paid for a kWh you send back. Full-retail net metering credits exports at the retail rate. Net billing pays an avoided-cost rate — in California's NEM 3.0, roughly 3.7–4.6 ¢/kWh for 2025–2026 applicants, against retail rates near 30 ¢. This calculator puts the two regimes side by side on the same system: switch the export setting and watch year-one savings, payback and the 25-year cumulative line move. After the federal credit disappeared in 2026, the export rule became the single largest state-level variable in most solar economics.
Your inputs
Change any default to match your bill, your quote and your utility tariff.
Household and price
Roof and solar resource
Money, financing and 25-year assumptions
Your estimate
Federal residential credit (2026)
$0.
Itemized cost
Ownership comparison · 25-year net
| Cash purchase | — |
|---|---|
| Loan (after payments) | — |
| Lease / PPA (no upfront) | — |
| Loan monthly payment | — |
The cash and loan rows both exclude any federal credit. A third-party owner, not you, may claim section 48E.
Environmental scale
| CO₂ avoided in year one | — |
|---|---|
| Mature-tree equivalent | — |
| Gasoline car miles | — |
Uses 0.855 lb CO₂/kWh (U.S. grid average), 48 lb/tree/year and 0.89 lb/mile.
25-year cumulative net cash flow
Sensitivity to utility rate escalation
| Annual escalation | Payback | 25-year net |
|---|
Year-by-year cash flow
| Year | Production kWh | Bill savings | Maintenance | Net | Cumulative |
|---|
How this is calculated
Under full-retail net metering, self-consumed kWh = min(production, annual usage) and any surplus is valued at the retail rate. Under net billing, self-consumed kWh = min(production, annual usage × self-consumption share) and the rest is valued at the export credit. The self-consumption share defaults to 45% and rises with battery capacity. Every other input — array size, cost, degradation, escalation — is held constant, so the difference between the two runs is attributable to the export rule alone (subject to the annual true-up caps a real utility may impose).
A worked example
Take an 8 kW array producing about 12,700 kWh a year in a state with a 29.75 ¢ retail rate. If exports earn full retail, nearly every kWh is worth close to 30 ¢. If exports earn 4.2 ¢ and only 45% of generation is used on site, roughly 7,000 kWh are valued at 4.2 ¢ rather than 29.75 ¢ — about $1,700 a year of lost value. That gap is precisely why batteries are now standard in NEM 3.0 proposals and largely optional in full-retail states.
What this tool does not do
It does not model hourly avoided-cost curves, time-of-use periods, annual true-up caps, non-bypassable charges, minimum bills, or the nine-year export-rate vintage lock in California. A utility's bill-impact analysis built on your interval data is the authoritative number.
Practical checks before you compare quotes
- Get the export rate in cents, in writing, before comparing quotes.
- Ask whether the rate is locked and for how long.
- Request an interval-data bill-impact analysis, not a 12-month average.
- Re-run this page with your real self-consumption if you have a smart meter.
Common mistakes
- Assuming 'net metering' means full retail everywhere.
- Oversizing under net billing.
- Comparing exported kWh to retail kWh as if they were equal.
- Ignoring fixed monthly charges that solar cannot offset.
Planning estimates only — not a quote, tax advice, legal advice or financial advice. State benchmarks are not your utility tariff. Verify every incentive with the program administrator and get at least three written installer quotes.
Frequently asked questions
What is the difference between net metering and net billing?
Net metering credits exported energy at or near the retail rate. Net billing values it at an avoided-cost or wholesale-derived rate, typically far lower. The names vary by state; the tariff is what matters.
What does California NEM 3.0 pay?
For 2025–2026 applicants, published averages are about 3.9 ¢ (PG&E), 4.6 ¢ (SCE) and 3.7 ¢ (SDG&E) per kWh, locked for nine years by application vintage. The California Supreme Court declined further review in June 2026.
Does a battery fix net billing?
It helps. Storage raises self-consumption so fewer kWh are sold at the low export rate, but it adds cost and has its own payback. Compare the 25-year net with and without it.
Why does my state say 'varies'?
Because we could not verify a single statewide residential export rule for it. Some states leave buyback terms entirely to the utility or retail plan. We default to a conservative 5 ¢/kWh and ask you to confirm with your utility.
Sources and further reading
- HelioCalc methodology and calculation kernel
- IRS FS-2025-05 (2026 federal credit rule)
- EIA Electric Power Monthly, Table 5.6.A, August 2026