How it works
Stage1Energy runs a roof through five sequential phases — from postcode to decision-ready output — without a site visit, specialist software, or prior solar knowledge. Each phase builds on the last. Nothing is assumed away; every assumption is shown.
The screen opens with a postcode. From there, the tool resolves the site location and automatically pulls the data needed to model that specific roof in that specific location: irradiance from European Commission satellite records, wind exposure from location-derived proxies, grid connection context, and UK electricity tariff benchmarks. If you have energy invoices to hand, you can add them — the tool reads consumption and cost figures directly. If not, it applies UK commercial benchmarks for the property type and moves on. By the end of Phase 1, the site has a full environmental and economic baseline anchored to the postcode, not a national average.
Using a satellite image of the site, you trace the roof outline directly on screen — no CAD file, no drone survey, no measurements taken in advance. The trace takes a few minutes. Pitch and orientation are entered alongside it. From the traced outline, the tool calculates the usable array area, accounting for setbacks, inter-row spacing, and obstacles, using the roof type and geometry you have provided. This is the step that separates Stage1Energy from postcode-level calculators: the roof that gets modelled is the actual roof at that address, not a statistical stand-in.
With the roof geometry established, Phase 3 works through the site-specific inputs that shape what a system on that roof can realistically do. Roof construction type, existing structural context, grid connection type, and your objective — whether the priority is return on investment, carbon reduction, or a balance of both — are all captured here. The questions are short and plain-English. No solar knowledge is needed to answer them. Where inputs have a meaningful effect on the output, the tool flags what is driving the result and what would change it.
The modelling runs automatically once the inputs are complete. Phase 4 returns the screen results: estimated system size in kWp, projected annual generation, a 25-year financial value range, simple payback indicator, and a set of engineering flags covering wind uplift loading zone, structural loading context, and DNO export threshold. Each output is tied to the assumptions that produced it — the result is a scenario-led range with the variables shown, not a single optimistic number. A plain-English summary sits alongside the numbers, stating whether the site warrants further investment and what the key factors are.
The screen output can be exported as a structured PDF report. The report carries the site reference, all modelling inputs, the output range, the engineering flags, and the plain-English recommendation — in a format that can be filed, forwarded, or used as the basis for a conversation with an installer, surveyor, or asset manager. It is not a design document or a formal energy assessment. It is a documented Stage 1 screen: enough to make a qualified go or no-go decision, with the reasoning on paper.
A roof that went in as a postcode comes out as an assessed site — with a system size range, a generation estimate grounded in location-specific irradiance data, a 25-year financial envelope, and a clear view of whether the engineering flags anything that changes the case. The screen takes under ten minutes. The output is detailed enough to decide whether survey time, specialist resource, or client expectation are justified.
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