How the numbers are made.

Data sources

Data last changed: October 6, 2026 (last checked October 6, 2026). The refresh runs on a schedule, rebuilds the site when something changed, and updates every page and this table. Nobody edits numbers by hand.

Definitions

• Average residential price = residential revenue ÷ residential kWh sold, in cents per kWh. All-in: energy, delivery, riders, fuel/power-cost adjustments and the fixed customer charge, spread across all kWh. It excludes consumption taxes that the utility collects and passes through, per EIA's Form 861 instructions. Not a tariff rate.
• Utility one-year change = latest year's price ÷ prior year's price − 1. Per year since first is the compound annual growth rate over the available years.
• Average monthly kWh per home = residential kWh sold ÷ residential customers ÷ 12.
• Trailing 12 months = revenue-weighted average of the latest twelve monthly figures.
• US monthly price = revenue-weighted across all states from the same EIA file. Annual averages (Virginia and US, 2010 on) are revenue-weighted over the twelve months; 1990–2009 come from EIA's historical state file.
• Calculator default rate = Virginia's revenue-weighted trailing-12-month average, currently 16.48¢ (to July 2026). A single preliminary month is too noisy to anchor a 25-year estimate.
• Average bill = residential revenue ÷ customer-months over the trailing 12 months (statewide, EIA-861M) or average monthly kWh × average price (per utility).
• Production per kW = PVWatts AC output for a 1 kW DC system: fixed roof mount, azimuth 180° (south), tilt 25°, standard modules, 14% system losses. Reported in kWh per kW-DC per year.
• Virginia median production = median of the per-town figures: currently 1,389.
• Early release (*): EIA's preliminary annual file. Some utilities are excluded pending validation; for those, the previous final year is shown and labeled.

Calculator formulas

1. Annual usage (kWh) = monthly bill ÷ rate × 12. The rate is all-in (bill ÷ kWh, before taxes).
2. Energy rate = rate − (fixed charges × 12 ÷ usage), floored at zero. The all-in rate already contains the fixed customer charge, which solar cannot avoid, so only the energy portion is applied to replaced kWh.
3. Effective production per kW = PVWatts production × roof factor × shade factor.
4. System size (kW DC) = usage × offset ÷ effective production, capped at 25 kW, rounded to 0.1 kW.
5. Gross cost = size × 1,000 × $/W. Net cost = gross × (1 − federal credit ÷ 100), with the credit a percentage from 0 to 100.
6. For year n = 1…25: energy rate_n = energy rate × (1 + escalation)ⁿ⁻¹; production_n = year-1 production × (1 − degradation)ⁿ⁻¹. Fixed charges are held flat.
7. Bill without solar_n = usage × energy rate_n + fixed charges × 12 (so year 1 equals the bill you typed). Bill with solar_n = max(usage − production_n, 0) × energy rate_n + fixed charges × 12. (One-for-one net metering; surplus beyond annual usage earns nothing.)
8. SREC income_n = ⌊production_n ÷ 1,000⌋ × SREC price, for n ≤ 10.
9. Savings_n = bill without − bill with + SRECs. Break-even = first year cumulative savings ≥ net cost, interpolated within the year.
10. Net benefit = cumulative savings − net cost over 25 years, in nominal dollars. Nothing is discounted to present value, and no inverter replacement or maintenance is deducted.
11. Chart lines: cumulative bills without solar vs. net cost + cumulative bills with solar − cumulative SRECs.

Default assumptions

Policy facts

• Federal residential credit: The 30% federal residential clean energy credit (Section 25D) ended for expenditures made after December 31, 2025, which the IRS treats as the date installation is completed. Homeowner-owned systems installed in 2026 or later do not receive it. Leased and power-purchase-agreement systems are owned by the installer or financier, who may still claim the separate commercial credit (Section 48E) subject to its own construction deadlines and sourcing rules; whether any of that reaches the homeowner depends on the contract. This is not tax advice. Confirm your own situation with a tax professional.
• Net metering (general): Virginia's investor-owned utilities and electric cooperatives credit exported solar at the full retail rate, with credits carried forward for 12 months. The State Corporation Commission's April 30, 2026 ruling on Dominion's net-metering case kept full retail crediting in place. Credits roll over 12 months.
• Dominion Energy: Dominion customers enrolling after April 30, 2026 are on the SCC's revised terms: full retail credit for exports, a $1-per-month net-metering administrative fee, year-end excess credits paid out at 5.829 cents per kWh rather than carried forward, renewable-energy certificates kept by the customer, and systems sized up to 150% of the prior 12 months' usage. A standby charge applies to residential systems above 15 kW (rising to 20 kW on January 1, 2027 under 2026's HB 1255). Customers enrolled before the ruling keep their existing terms.
• Appalachian Power: Appalachian Power customers keep full retail crediting under the SCC's August 29, 2025 order. For customers enrolling after that order, credits left over at the end of the 12-month period are paid out at roughly one-third of the retail rate rather than carried forward. Appalachian Power has no residential standby charge.
• Investor-owned program cap: For Dominion and Appalachian Power, net metering stays open until enrolled capacity reaches 6% of the utility's adjusted prior-year peak load (5% general plus 1% reserved for low-income customers).
• Cooperatives: Electric cooperatives net meter under a separate section of the statute (§ 56-594.01). Each cooperative's board sets its own program cap, fees and interconnection paperwork, and at least one Virginia cooperative has reached its cap in the past, so check the current tariff before signing.
• Municipal and university utilities: Municipal and university-owned utilities are not covered by Virginia's net-metering statute and set their own policies. Some offer a comparable retail credit, some do not; check the utility's tariff before sizing a system.
• SRECs: Virginia homes earn one Solar Renewable Energy Certificate per 1,000 kWh produced. SRECs trade on an open market and prices move; the default here is a planning estimate you should edit. The Virginia Clean Economy Act requires Dominion and Appalachian Power to retire certificates from Virginia-sited distributed solar. HB 628, signed April 13, 2026, raised Dominion's distributed-solar carve-out to 4.5% of its renewable obligation for 2026 through 2030 (5% from 2031). The 2026 deficiency payment for that carve-out is $78.82 per MWh, which acts as a ceiling on what a certificate can be worth.

Reviewed 2026-10-06. Sources: Virtue Solar — Virginia solar incentives (kept current); Virtue Solar — SCC final ruling on Dominion NEM 2.0 (May 2026); pv magazine — SCC approves Dominion net metering terms (May 2026); Cardinal News — Appalachian Power net metering order (Sept 2025); Code of Virginia § 56-594 (net energy metering); IRS — One Big Beautiful Bill provisions (Section 25D sunset); Flett Exchange — Virginia distributed SREC market; Virtue Solar — APCo net metering preserved (Sept 2025); Virtue Solar — What the One Big Beautiful Bill means for solar in Virginia; Virtue Solar — Dominion standby fees explained; Virtue Solar — What are SRECs (with current Virginia prices); Virtue Solar — How much does solar cost; Virtue Solar — Third-party-owned solar financing. Policy moves; when it does, the pages that depend on it carry this review date so you can judge staleness.

Known limitations

• Utility prices are calendar-year averages. Cooperative power-cost adjustments change mid-year; the current tariff may differ from the average shown.
• ZIP codes can straddle counties. The calculator lists every current utility serving any county the ZIP touches and lets you pick; where a county has more than one utility, it does not guess.
• Utilities that last reported residential data to EIA more than two annual files ago (several small municipals and co-ops on EIA's short form) are left out of city pages, the calculator and the ranking rather than shown with stale prices.
• Production is for a generic south-facing roof. Real shade, roof planes and panel layout change it.
• The calculator ignores financing interest, inverter replacement, maintenance, insurance, property-value effects, time-of-use rates, standby charges, battery economics, the small year-end payout for surplus credits, and any future change to net metering for new customers. All dollars are nominal; nothing is discounted.
• PVWatts uses typical-meteorological-year data. Any single year can be sunnier or cloudier.
• EIA early-release data is unvalidated and is marked wherever it appears.

Independence

GoSolarVA is operated by Virtue Solar, a solar installer. The data, formulas and assumptions are published here precisely so that bias can be checked. Nothing on the site changes based on who is reading it, and the calculator will happily tell you solar does not pencil out.