Our sources and methodology

See the work behind your review.

A finding is more useful when you can see what supports it. Here is the data we use, how it becomes a check, and where the evidence stops.

From a proposal to a finding

We review the residential solar proposal you upload and, on the Bid + Contract plan, the contract that goes with it. The aim is to explain whether the stated claims are internally consistent and supported by the information available.

Read what the documents say. We identify the system, price, production, savings, equipment and terms. You confirm the important extracted fields.
Compare with independent references. Models, published data and documented review rules help us examine the proposal. A source’s facts and BidProof’s interpretation are different, and the finding should make that clear.
Explain the result and its limits. The report names concerns, assumptions and missing information, with questions you can take back to the seller. A reviewer examines cases that need a closer look; not every proposal receives manual review.

Solar engineering, pricing, operations and software experience inform the checks. Meet the people behind BidProof, or read a sample report.

Look it up yourself

Where the numbers come from.

The source is listed beside the homeowner question it helps answer. Editions below describe the references used here, which may differ from a publisher’s newest release.

These organizations publish data. They do not review, endorse or partner with BidProof.

Will it produce what the proposal says?

PVWatts

National Laboratory of the Rockies (formerly NREL)

Provides an independent energy-production estimate using the location and available system and roof details, for comparison with the proposal’s yearly output.

Edition and currency: PVWatts V8 model. Results depend on the inputs available for the review.
What to keep in mind: A modeled estimate is not a performance guarantee. Missing inputs and assumptions affect confidence; a document review is not an on-site survey.

Does the system fit the household’s usage?

ResStock

National Laboratory of the Rockies (formerly NREL)

Provides climate- and heating-fuel-based usage patterns and regional baselines. These help assess stated electricity use and estimate a full year when only part of a bill history is available.

Edition and currency: NREL ResStock 2024 TMY3 release 2 - 10th percentile annual electricity, single-family occupied homes, by county/climate zone and heating fuel
What to keep in mind: Modeled usage is a baseline, not the household’s measured consumption. This usage baseline covers the lower 48 states and DC, not Alaska, Hawaii or the territories.

Do the savings assumptions hold up?

Forms EIA-861 and HS861

U.S. Energy Information Administration

Provides residential electricity-rate benchmarks and historical changes. Utility history is used where available, with state or national history as a fallback.

Edition and currency: EIA-861 (2024) - Sales to Ultimate Customers, residential bundled service, 2004-2024 history; EIA HS861 (2024) - state-level residential Total Electric Industry, 1990-2024 history.
What to keep in mind: These blended residential averages are benchmarks, not the household’s tariff, marginal rate or export credit. Utilities have different lengths of history. Newer publisher releases are not automatically part of the tables used here.

Can the named equipment be looked up?

Solar Equipment Lists

California Energy Commission

The downloaded catalog supports model matching for panels, inverters, energy storage systems and batteries named in the documents.

Edition and currency: Catalog editions vary by list. A live catalog verification date is not available on this page.
What to keep in mind: Listing is not a certification by BidProof or a guarantee of safety, performance or durability. CEC does not confirm manufacturers’ self-reported information, and listing is not universally required for installation. Publisher updates and BidProof’s scheduled catalog refresh are separate.

How does the quoted price compare?

Ohm Analytics

Provides state and national residential solar proposal-price medians and national storage-price medians for the Project Price check. The proposal data excludes financing costs, including dealer fees. BidProof uses the median of the latest three months in its maintained table and applies its documented reference-envelope rules alongside Berkeley Lab’s installed-price research.

Edition and currency: Ohm Analytics 2026-10-02 + LBNL Tracking the Sun 2026
What to keep in mind: Price depends on size, scope, geography and payment structure. The state solar reference falls back to national data when a qualifying state figure is unavailable or unsuitable; the storage reference is national. These are proposal-price benchmarks, not a fresh market lookup, a lease or PPA payment benchmark, or a promise of a market-matched quote.

How are price benchmarks grounded?

Tracking the Sun

Lawrence Berkeley National Laboratory

Tracking the Sun supplies the national installed-price reference for the upper end of BidProof’s solar price envelope, used alongside Ohm Analytics proposal-price medians. BidProof applies its documented reference-envelope rules; it does not fetch a fresh market distribution for each proposal.

Edition and currency: Ohm Analytics 2026-10-02 + LBNL Tracking the Sun 2026
What to keep in mind: Installed-price research and proposal-price data measure different things. Price depends on size, scope, geography and payment structure. An installed-price reference is not a lease or PPA payment benchmark, and does not promise a market-matched quote.

Which utility’s rates should be considered?

U.S. Electric Utility Companies and Rates: Look-up by Zip Code

DOE Open Energy Data Initiative (OEDI) · NREL dataset

Provides candidate utilities for a ZIP code so the household can identify the utility serving the home. BidProof uses the utility mapping, rather than this dataset’s rate columns, for this step.

Edition and currency: OEDI submission 8563 — U.S. Electric Utility Companies and Rates: Look-up by Zip Code (2024)
What to keep in mind: A ZIP can map to multiple utilities. The mapping is not proof of the supplier or tariff at a specific address.

U.S. Electric Utility Companies and Rates: Look-up by Zip Code, National Renewable Energy Laboratory (NREL), via OEDI. Licensed CC BY 4.0. Adapted by BidProof into a ZIP-to-utility lookup. Read the license.

Which location and climate baseline apply?

ZCTA Gazetteer and geographic relationship files

U.S. Census Bureau

ZIP-area locations support the production model. Geographic relationships connect ZIP areas to county-based climate information for usage estimates.

Edition and currency: 2025_Gaz_zcta_national.txt; US Census 2020 ZCTA-to-county relationship file (tab20_zcta520_county20_natl) joined to NREL ResStock ASHRAE 169-2004 / IECC 2012 county climate zones (M.C. Baechler 2015; Census 2015 county definitions).
What to keep in mind: A ZIP-area center is not a roof measurement. Some ZIPs, including some PO-box ZIPs, have no mapped area or climate assignment. Missing coverage is not replaced with a neighboring area.

Should a claimed federal credit be counted?

Residential Clean Energy Credit guidance

Internal Revenue Service

The published federal-credit guidance is the reference for the review’s federal solar-credit timing checks. It is not a live lookup of every state or utility incentive.

Edition and currency: Public IRS guidance checked October 24, 2026. The review uses documented credit-timing rules.
What to keep in mind: A proposal review does not establish personal tax eligibility or provide tax advice. Confirm the rules for your circumstances with the IRS and a qualified tax adviser.

Other references used where available

Utility tariff filings and state utility commission orders inform selected export-value rules. Manufacturer-published specifications and warranties support equipment, battery and warranty comparisons. Coverage depends on the source and the details in the proposal; naming a manufacturer is not an endorsement.

Source editions, the date data was imported, and a person’s last verification are different facts. We do not present an import date or today’s date as proof that every record has been independently rechecked.

For the CEC list’s scope and qualifications, read the Solar Equipment Lists program explanation.

What the evidence can and cannot tell you

We accept residential proposals across the United States. Data coverage varies. A missing model number, unknown rate plan or uncovered geography can limit a check. The report identifies missing evidence and checks it could not complete, rather than treating an absence of data as a pass.

The licensing check looks for the contractor’s identity and a license number in the documents. It does not confirm an active license with a state licensing board. Read our coverage limits.

BidProof evaluates whether the proposal's claims are internally consistent and grounded in industry-standard data. It does not guarantee system performance.

Where a contract is reviewed, BidProof reports what the contract says, not what it means legally. BidProof is not a law firm.

This report is an independent review of your bid by experienced solar industry professionals. It is not professional legal, tax, financial or engineering advice.

Corrections and better questions

If a source changes or we misread a document, contact our team with the finding and the supporting information so we can examine and correct the record.

Our Fair Proposal Standard, version 1.0 draft, sets out what a proposal should disclose. Its recommendations are separate from the checks a BidProof review currently completes.

See the method in a sample report

Read the findings, assumptions and questions before choosing a review.

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