Editorial owner: MCL Solar Knowledge Center. Verification rule: Model-specific performance requires the relevant test report, site data, calculation, and contract documents. Last updated: July 16, 2026.
Key takeaways:
- Road lighting cannot be selected from watts, lumens, pole height, or a beam-angle label alone.
- Use a model-specific IES or LDT file and a project DIALux calculation.
- Report average illuminance, uniformity, glare or TI where applicable, and every geometry and maintenance assumption.
- IES Type II and Type III describe intensity distribution; they are not equivalent to a single angle.
Inputs required before simulation
| Area | Required input |
|---|---|
| Road | Width, lanes, surface, conflict areas, and target lighting class |
| Geometry | Pole height, spacing, setback, overhang, outreach, tilt, and arrangement |
| Luminaire | Exact model, LED input power, measured flux, and IES or LDT distribution |
| Calculation | Grid, maintenance factor, average illuminance or luminance, uniformity, and glare or TI where applicable |
| Energy | Night profile, worst-month PSH, battery assumptions, PV losses, and recovery requirement |
Photometric standards and reports
LM-79 covers photometric and electrical measurements of complete solid-state lighting products. LM-80 covers lumen-maintenance testing of LED packages, arrays, or modules. They are not interchangeable. A complete luminaire life claim may use LM-79 measurements together with component maintenance data and an appropriate projection method, subject to report scope.
Spacing and pole height
Spacing-to-height rules can support a preliminary concept but do not prove compliance. Verify the exact road, pole, bracket, and luminaire distribution in the simulation. The selected result must also fit structural wind loading, foundation design, maintenance access, and photovoltaic exposure.
Acceptance package
- Model-specific LM-79 or equivalent photometric report
- IES or LDT file matching the proposed optic
- DIALux report with all inputs and result tables
- Installation drawing and pole or foundation calculation scope
- Commissioning measurements and acceptance method
Why rural-road and highway spacing ratios need photometric validation
Height-to-spacing ratios are useful for initial layout studies, but they cannot confirm compliance. Rural roads, multi-lane highways, curves, intersections and medians create different lateral and longitudinal distribution requirements. The same ratio can produce different uniformity and glare when the optical file or pole arrangement changes.
Use ratios to generate alternatives, then test each alternative with the exact IES or LDT file, road surface, maintenance factor and acceptance criteria. Record the final pole height, setback, overhang, tilt and spacing in the calculation report and installation drawing.
Tender-readiness checklist for municipal and EPC solar street lighting
A tender-ready solar street lighting proposal should show how the selected system fits the road geometry, required lighting performance and available solar energy. Before comparing quotations, ask each bidder to state the project inputs used, provide documents that match the proposed model, and identify which engineering responsibilities remain with the project team.
Tender items to request
- Road and lighting inputs: road width, lanes, pole arrangement, mounting height, spacing, target lighting class and operating profile.
- Photometric evidence: model-specific IES/LDT data and DIALux results with stated inputs and results.
- Energy-sizing basis: project location, solar-resource basis, night profile, autonomy, PV losses and recovery assumptions.
- Product documents: the proposed optic, component configuration, data sheet and installation drawing.
- Acceptance plan: commissioning, measurement, document handover, and spare or service responsibilities.
Define the responsibility boundary before award
Ask each bidder to distinguish delivered product documentation, site-specific photometric and energy calculations, civil or structural design, installation, commissioning and acceptance measurement. Contract documents should identify the party responsible for each output and which project inputs must be confirmed before final design.
Questions to resolve before a purchase order
- Which exact luminaire model and optical file are included in the calculation?
- Which assumptions are preliminary, and which must be verified against the final site survey?
- What documents will be provided for design review, installation and acceptance?
- How will changes in road geometry, shading or operating profile be handled before commissioning?
Use this checklist together with the road-design inputs and acceptance package above. It helps procurement teams compare proposals on documented design assumptions rather than on headline wattage or a single beam-angle label.