Solar Panel Savings Calculator

How to use this calculator

Plug in five numbers and the tool returns year-1 savings, average monthly cash flow, 10-year savings, and the full 25-year lifetime savings:

1. Annual production (kWh) — what your system produces in year 1. Use NREL PVWatts (free at pvwatts.nrel.gov) or the production estimate from your installer’s quote. A 7 kW system in Phoenix produces about 12,000 kWh/year; the same system in Seattle produces about 8,000 kWh/year.
2. Electricity rate ($/kWh) — your blended residential rate. Look at the bottom of your utility bill: total dollars divided by total kWh. The 2026 U.S. residential average per EIA is roughly $0.16/kWh, but PG&E Tier 4 customers in California pay $0.45+/kWh while Idaho Power customers pay around $0.10/kWh.
3. Export / net-metering rate ($/kWh) — under NEM 1.0/2.0 (most states), this equals your retail rate. Under NEM 3.0 (California), it averages $0.05-0.08/kWh. Under sell-all/buy-all systems (a few municipalities), it equals the utility’s avoided-cost rate.
4. Self-consumption (%) — the fraction of solar production used directly by your home before any goes to the grid. Without a battery, typical residential self-consumption is 25-40%. With a battery + time-of-use shifting, it rises to 60-85%. Under retail-rate net metering, self-consumption percentage doesn’t affect the dollar number (rate equals export rate), so leave it at 100%.
5. Annual rate escalation (%) — historical U.S. average is 2.7%, EnergySage default is 3%, EIA’s 2025 forecast is 3.5%. Use 3% unless you have specific reason to deviate.

How the math works

Solar savings is an energy-cost-displacement calculation that splits each kWh between self-consumed (offsets retail) and exported (paid at the export rate), with annual rate escalation and 0.5%/year panel degradation:

year_n_self_kWh   = annual_kWh × (1 - 0.005)^(n-1) × self_pct
year_n_export_kWh = annual_kWh × (1 - 0.005)^(n-1) × (1 - self_pct)
year_n_savings    = year_n_self_kWh × rate × (1 + escalation)^(n-1)
                  + year_n_export_kWh × export_rate
lifetime_savings  = sum of year_n_savings from y = 1 to y = 25

Worked example for a typical Phoenix home:

• Production: 12,000 kWh/year
• Rate: $0.13/kWh (APS residential blended)
• Self-consumption: 100% (Arizona net metering at retail rate)
• Escalation: 3%
• Year 1 savings: 12,000 × $0.13 = $1,560
• Year 25 savings: 12,000 × 0.995^24 × $0.13 × 1.03^24 ≈ $2,780
• Lifetime total: roughly $53,000

The compound effect of 3% rate escalation × 25 years roughly doubles the year-25 dollar value of each kWh saved.

25-year savings by U.S. region (2026 reference)

Based on EnergySage marketplace data and NREL Standard Scenarios, lifetime savings for a typical 7 kW residential system at 100% net-metering:

What changes lifetime savings

Increases savings

• High retail rates — California Tier 4, Hawaii, Massachusetts, and the Northeast.
• Time-of-use rates with peak afternoon pricing — solar generates exactly when peak rates apply, so each displaced kWh is worth more than the blended-rate average.
• 1:1 retail-rate net metering — currently in NY, MA, NJ, FL, TX, and most non-NEM-3 states.
• Battery + TOU shifting — pairs well with NEM 3.0 and demand-charge tariffs by lifting self-consumption from 30% to 75%+.
• State and local incentives — SREC programs in NJ, MD, MA, IL, OH, DC.

Decreases savings

• NEM 3.0 / “successor” net-metering tariffs — California 2023+ exports compensated at avoided-cost (about 25-30% of retail).
• Demand charges — common in Arizona APS and parts of Nevada — solar reduces kWh but may not reduce monthly demand spikes.
• Time-of-use rates with cheap afternoon pricing — some utilities have shifted peak windows to 4-9 PM (after solar peak), which compresses self-consumption value.
• Inverter replacement — typical 12-15 year inverter lifespan means most owners replace once over the 25-year horizon ($1,500-$3,000 depending on system size).

Savings vs. payback vs. ROI

Three closely related metrics that answer different questions:

• Lifetime savings answers “How much money over 25 years?” — useful for understanding the absolute scale of the investment return.
• Payback period answers “When do I break even?” — useful for risk-averse homeowners and short time horizons.
• ROI / IRR answers “What annualized rate of return does this match?” — directly comparable to S&P 500 or bond yields.

Run all three before signing a contract. See our solar payback calculator for the year you break even and our solar ROI calculator for the full IRR picture.

Pair this with the payback calculator, ROI calculator, and system cost calculator

Savings shows total dollars saved; payback shows the break-even year; ROI shows the lifetime return rate; system cost gives the up-front capital outlay. Run all four before you commit, and check your tariff schedule with your utility before plugging in your rate.

Sources

• EIA Form 861 + Short-Term Energy Outlook — residential rate history and forecast.
• EnergySage Solar Marketplace Report H2 2025 — installed cost-per-watt and savings benchmarks.
• NREL PVWatts — first-year production estimate for any U.S. address.
• NREL Standard Scenarios 2025 — degradation, lifetime, and ITC modeling assumptions.
• DSIRE database (NC State) — state and local incentive details, plus current net-metering rules.
• SEIA / Wood Mackenzie U.S. Solar Market Insight — market and policy data.