The EcoGen Solar Database: How Our Numbers Are Built
The EcoGen Solar Database brings together the state inputs and modeled figures behind our solar research. Its current cost method is the September 2026 Solar Cost Index. This page explains the records; the methodology page explains the calculation.
A useful solar estimate needs context: what it includes, where its inputs came from and whether it describes a typical system or your particular home. The Database makes those distinctions easier to follow.
We built the EcoGen Solar Database to organize our research across the 50 states and Washington, DC. It connects cost benchmarks with household electricity use, local production and the assumptions needed to interpret a result. Our data and analytics team is led by Trevor Guilday.
What the EcoGen Solar Database Contains
The Database is the umbrella. Underneath it sit four named components, each answering a different question and each carrying its own sources and dates.
EcoGen Solar Cost Index
The modeled installed price per watt before incentives, calculated using the September 2026 method. It provides a consistent starting point for comparing states.
EcoGen Solar Payback Methodology
The separate assumptions used to estimate payback and longer-term savings. A new cost-model edition does not automatically change this assumption set.
State Profile
The household picture for each state: average monthly consumption, the residential electricity rate, the resulting monthly bill, the solar production a kilowatt actually delivers there, and the system size that combination calls for.
EcoGen Installer Index
The installer side of the Database: who serves which state, what each company publishes about itself, and what the state licensing registry says when we look the number up ourselves. Ranking weights for installers are published separately on each state’s companies page.
How the EcoGen Solar Cost Index Is Built
Current cost-model edition: September 2026. The pricing model has four stages.
1. Start with a system-cost benchmark
The EcoGen Solar Cost Index, September 2026 edition, is built by the EcoGen data and analytics team, led by Trevor Guilday. It starts from the Q1 2025 Solar Photovoltaic System Cost Benchmarks published by the Department of Energy‘s National Laboratory of the Rockies (formerly NREL). That benchmark breaks the price of a home solar system into cost categories, from equipment to field labor and office costs.
2. Adjust for state wages and system size
We adjust the labor costs for each state using Bureau of Labor Statistics wage data for solar installers, or for electricians where installer wages are not published. We size a typical household system for each state from U.S. Energy Information Administration electricity-use data and local sunlight. Each state’s figure comes from EcoGen’s proprietary cost model, calibrated against current marketplace quote data from across the country.
3. Compare with completed installations
Then we check the result against what homeowners actually paid. In the 21 states covered by Lawrence Berkeley National Laboratory‘s 2026 transacted-price data, each state’s figure is compared with real installed prices.
A dataset’s publication year is not necessarily the installation year. Outside the 21-state comparison coverage, do not read a modeled figure as a checked local transaction average.
4. Calculate a consistent national benchmark
Add the 50 state figures and the District of Columbia figure, then divide by 51. Each jurisdiction has equal weight; this is not an installation-volume or population-weighted average.
How we calculate solar costs · What goes into each state’s row
The Payback Assumptions, Published in Full
Payback requires its own assumptions as well as a cost estimate. The assumptions below are set separately from the cost method and did not change with the September 2026 edition. Check the assumptions and scenario used on the article you are reading.
Assumption | Setting | Why it is set this way |
|---|---|---|
Federal credit, systems you buy | 0% | The 30% Section 25D residential credit ended for systems placed in service after December 31, 2025. Modeling it would overstate savings. |
Federal credit, leases and PPAs | Section 48E only | A third party that owns the system can still claim a commercial credit. The homeowner does not. |
Electricity rate escalation | The state’s own 5-year growth rate, floored at 2% and capped at 4% | Using each state’s actual recent history beats a single national guess. The floor and cap stop an unusual few years from producing a fantasy payback. |
Panel degradation | 0.5% per year | Standard manufacturer warranty territory. Production falls slightly every year and the model reflects it. |
Horizon | 25 years | Matches typical equipment warranty length, so the savings figure covers a period the equipment is warranted for. |
Where the State Profile Numbers Come From
Each record combines external evidence with EcoGen calculations. A source period, a retrieval date and a model edition answer different questions.
Input or output | Basis | How to read it |
|---|---|---|
Labor adjustment | Solar-installer wages; electrician fallback when unavailable. | |
Household consumption | Representative use, not your individual bill. | |
System size | Electricity use and local sunlight | A modeled capacity, not a roof design. |
Installed price per watt | EcoGen proprietary cost model | Calibrated against marketplace quotes. |
Installed-price comparison | Available in 21 states for this edition. | |
National benchmark | 50 states + Washington, DC | Plain average of 51 jurisdiction figures. |
Gross system cost relates modeled capacity to price per watt. Payback additionally depends on generation, utility rates, export compensation, incentives and financing. Do not compare a solar-only cash benchmark with a battery-inclusive or financed quote without accounting for the difference.
Explore the solar cost and savings calculator. State benchmarks are a starting point, not a personalized quote.
What We Deliberately Do Not Do
How Often the Numbers Change
The model edition, source observation period and retrieval date should be read separately. The September 2026 edition updates the cost method; payback assumptions and installer records have their own scope and dates.
When comparing figures across pages, check their stated edition and included costs. Report a discrepancy to contact@ecogenamerica.com with the page URL, state and number.
Frequently Asked Questions
Is the Database EcoGen’s own research resource?
Yes. EcoGen organizes the records and develops the proprietary model. External wage, electricity-use and installed-price datasets remain the work of their publishers.
How does the Database differ from the Cost Index?
The Database is the organized research resource. The Cost Index is its model for state solar price benchmarks. Read the method.
Why might my quote differ?
Your roof, equipment, system size, storage, installation scope and financing may differ from the representative scenario.
Does the September 2026 edition change the payback assumptions?
No. The payback assumptions are set separately from the cost method and did not change with this edition.
Can I check a particular state’s inputs?
Contact us with the state you want to understand, and we’ll explain which sources and assumptions shaped its figure.
Sources
- National Laboratory of the Rockies: Q1 2025 Solar Photovoltaic System Cost Benchmarks. NLR/OT-7A40-97930; DOI 10.7799/3009689. Dataset updated March 12, 2026.
- Bureau of Labor Statistics: Occupational Employment and Wage Statistics, May 2025. Solar photovoltaic installers (47-2231); electricians (47-2111) where installer wages are unavailable.
- U.S. Energy Information Administration: Form EIA-861, 2024 final data. Final files updated December 3, 2025.
- NREL PVWatts, website version 8.7.4, for local solar-production estimates.
- Lawrence Berkeley National Laboratory: U.S. Distributed Solar and Storage Data, 2026 Data Update (August 2026). The release date is distinct from the installation dates in the dataset.
- IRS: Residential Clean Energy Credit. Guidance on the credit’s end for property placed in service after December 31, 2025.
- DSIRE: Database of State Incentives for Renewables & Efficiency. Program and policy references; individual program dates and eligibility rules apply.
These are the source editions used for the September 2026 cost method and its supporting assumptions. Current marketplace quote data also calibrates EcoGen’s proprietary model. Organization links identify source publishers, not EcoGen partners.
Meet our team · Editorial standards · Full cost-method explanation