Assessment Methodology

What the assessment uses

The engine receives only the household and quotation fields you reviewed and confirmed. Uploaded documents and photographs remain in the browser. Text inside a quotation is treated as evidence, never as an instruction to the assessment system.

Five screening categories

• Quotation completeness: whether relevant price, equipment, financial and protection fields are stated.
• Product clarity: whether exact models, sizes and usable capacities are identifiable.
• Financial credibility: whether stated savings, generation and payback claims reconcile at a broad screening level.
• Consumer protection: stated certification, warranties, deposit, payment schedule and included work.
• Questions resolved: a deduction for material questions that still require written answers.

The overall score is the equal-weight mean of the five categories. A low protection, financial or completeness score can still produce “Do not sign yet”.

Facts, calculations and assumptions

Each finding labels its basis and confidence. A fact reports what is or is not stated. A calculation checks relationships such as price divided by annual saving. An assumption uses a broad screening benchmark and is not a site-specific forecast.

Solar generation screen

Broad annual yield factors range from 600 kWh/kWp for north-facing roofs to 950 kWh/kWp for south-facing roofs, before shading factors of 1.00, 0.88 or 0.72. A claim is flagged when it is more than 20% above or below the central estimate. This does not model roof pitch, local irradiance, obstructions, losses or detailed array design.

Payback screen

Implied simple payback is quoted price divided by claimed annual saving. A difference above 20% from the stated payback is flagged. Financing costs, degradation, tariff changes, maintenance and opportunity cost are not modelled.

Limits and safeguards

The service validates allowed selections, limits request size, sanitises control characters and never executes document text. It does not verify installer identity, MCS status, engineering suitability, legal terms or future performance. It is decision support—not a survey, valuation, guarantee, or financial, legal or engineering advice.

Version control and corrections

Every result displays its ruleset version. Thresholds and factors change only with a new published version. To question an assumption or report an error, email info@quoteguardian.co.uk with the version shown; do not include sensitive documents.