Finance

Compare the project economics with the assumptions visible.

Commercial decisions are easier when capex, finance structure, tariff assumptions, self-consumption and export value are separated clearly rather than hidden behind a headline payback figure.

KEEP THE NUMBERS TRACEABLE

A financial model is only useful when the engineering assumptions underneath it are visible.

Separate the physical system, energy assumptions and funding structure so the client can see which variables are driving the commercial result.

01Engineering inputs

System size, generation estimate, self-consumption, operating limits and expected degradation belong in the technical layer.

02Energy-value assumptions

Import cost, export value and tariff behaviour can move the result. These should be stated rather than hidden inside a headline payback figure.

03Funding structure

Cash purchase, lending or other arrangements change cashflow and total cost. Provider terms should be assessed separately from the engineering case.

CLIENT BENEFITA commercial case that can be stress-tested instead of accepted as a single sales number.

FINANCIAL MODEL

ROI should be reproducible from the assumptions.

The commercial model should allow a decision-maker to see which inputs drive the result and what happens if those inputs change.

CapexInstalled project cost and inclusions.

GenerationModelled annual output.

Self-useEnergy consumed on site.

TariffsImport and export assumptions.

SensitivityWhat changes the payback result.

PAYBACK INPUTS

A commercial model should be auditable.

Instead of presenting one payback number in isolation, the proposal should show the inputs that create it and separate measured site data from assumptions.

Input

Typical unit

What should support it

Annual generation

kWh / year

Site-specific PV model with roof, orientation, pitch and shading assumptions.

Self-consumption

% or kWh

Load profile — preferably interval data where available for commercial sites.

Import value

£ / kWh

Current bill/tariff assumptions, with any escalation stated separately.

Export value

£ / kWh

Actual or assumed export arrangement; no universal SEG rate should be implied.

Project cost

Defined installation scope, exclusions, optional works and finance terms where applicable.

Long-term assumptions

varies

Degradation, maintenance, replacement and operating assumptions shown explicitly.

Related guidance: Commercial solar ROI · Smart Export Guarantee.

Start with the site, not a sales script.

Business survey or homeowner quote — routed to the right questions from the first click.

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PROJECT ECONOMICS

The engineering design shapes the financial case.

Solar project finance visual — Compare tariff, installation cost and export assumptions in any business case.

PROJECT ECONOMICS

Understand what changes the financial case.

Any useful payback estimate starts with site demand, a defined scope and assumptions you can inspect.

Energy value

Import savings and export income

Generation that your site uses directly and generation exported to the grid have different values. The model should distinguish them.

Project scope

Compare like with like

Check the equipment, access, electrical work, permissions, commissioning and any ongoing service costs included in each proposal.

Finance choices

Review the complete terms

Compare total repayments, eligibility, rates and any ownership conditions before making a finance decision. No terms should be assumed without a provider quote.

CONNECTED ENERGY SYSTEM

Move between the parts of the system without starting over.

Solar generation, storage, EV charging and grid constraints affect each other. Use these routes to keep the project connected.

01 / BUSINESSCommercial energyLoad, roof, grid and project economics → 02 / HOMEHome energySolar, battery and EV starting point → 03 / GENERATESolar PVRoof, yield and array design → 04 / STOREBattery storagekW, kWh and control logic → 05 / CHARGEEV chargingHome, workplace and managed load → 06 / CONNECTGrid / DNOG98, G99, G100 and export →

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PROJECT ECONOMICS

Build the model around your site data.

A useful commercial model starts with demand, tariff and generation assumptions that can be challenged before the investment decision is made.

Discuss a commercial project