CCT / CRI / Beam Angle for Solar Street Lights — Procurement Spec Guide

CCT, CRI, and beam angle (optical distribution) determine what the road actually looks like at night: uniformity, glare, visual comfort, and how many lumens/power you need to hit the target. This guide turns these “lighting terms” into tender-ready specs and quote comparison rules.

TL;DR (What matters most)

Beam angle / distribution decides coverage and uniformity. Without an IES file + simulation, quotes are not comparable.
CCT is the color appearance (warm vs cool). Choose based on local preference/regulation and application (roads vs parks vs security).
CRI is color rendering. Higher CRI can help color identification but is not always necessary for roads.
Solar impact: optics and dimming drive average power (Wavg), which drives PV + battery sizing.

Core internal links for decision-making:

Definitions (procurement-friendly)

CCT (Correlated Color Temperature)

CCT describes how “warm” or “cool” the light looks (measured in Kelvin). CCT is about appearance and comfort; it is not a guarantee of better road compliance by itself.

CRI (Color Rendering Index)

CRI indicates how accurately colors appear under the light compared to a reference. Higher CRI can improve color identification (people/objects/signage), but may not be required for every roadway project.

Beam angle / Optical distribution

This is the light distribution pattern. For roads, you rarely want a simple “wide flood” claim — you want a defined distribution backed by an IES photometric file and a layout simulation. This is the #1 factor behind uniformity and glare outcomes.

Step 1) Choose beam angle / distribution first (because it controls uniformity)

Beam angle must match:

Road width and lane count
Pole layout type (single-side / staggered / opposite / median)
Mounting height and spacing (S/H)
Glare sensitivity (residential areas vs high-speed roads)

Use this with layout decisions:

Procurement rule (non-negotiable)

If a supplier cannot provide an IES file for the quoted optic AND a simulation PDF for your pole layout, treat the quote as Not Comparable / High Risk.

Step 2) Pick CCT based on application and constraints

CCT is usually a project preference/regulatory constraint. Choose a CCT range and enforce it consistently across bids.

Common application logic (keep it simple)

Urban streets / residential: often prefer warmer/neutral appearance for comfort (use local rules as priority).
Industrial / security-focused zones: may accept cooler appearance if that’s the site preference.
Parks / pedestrian areas: typically prioritize comfort and visual pleasantness.

Procurement tip: specify CCT as a range (not a single magic number) and require the supplier to declare their CCT tolerance/bins for the delivered batch.

Step 3) Decide CRI based on “color identification needs”

CRI requirements should be driven by purpose:

Standard roads: CRI can be a moderate requirement if your project does not need detailed color identification.
Security / CCTV / checkpoints / pedestrian-heavy areas: higher CRI can help recognize colors more naturally.

Procurement tip: don’t overpay for CRI if it does not serve your project goal. Enforce the same CRI target across all bidders if you require it.

Step 4) Lock “quote comparability” inputs (otherwise price is meaningless)

Two quotes are not comparable if they differ in optics or lighting assumptions. Require each bidder to declare:

Optic/distribution: IES file reference + optic name/code
Layout: pole height, spacing, arm length/overhang, pole position
CCT & CRI: declared values and tolerances
Dimming profile: time/PIR/hybrid and steps

Use these pages to enforce apples-to-apples:

Solar-specific reality: optics and dimming drive PV & battery sizing

When optics/layout choices require more lumens to meet targets, average power (Wavg) usually increases. That increases PV and battery sizing pressure — especially in rainy season or worst-month conditions.

Field acceptance checks (simple, auditable)

Optics match check: confirm delivered optic code matches the quoted IES/simulation package.
CCT consistency check: confirm delivered batch matches the declared CCT range; require batch declaration.
Commissioning record: confirm dimming profile matches the energy budget assumptions.
Evidence package: installation photos + serial-to-location mapping for warranty enforcement.

Reference:

PASS/FAIL procurement rules

Mark a bid FAIL (Not Comparable) if it lacks any of the following:

IES file for the quoted optic/distribution
Simulation PDF for your layout (pole height/spacing/placement)
Declared CCT and CRI (with declared tolerances/range)
Dimming profile disclosure (because it affects Wavg and sizing)

Copy/Paste RFQ Clauses (CCT / CRI / Beam Angle)

Clause 1 — Optics and IES file (mandatory)

Supplier shall declare the optical distribution/beam angle used and provide the corresponding IES photometric file for the quoted configuration. Quotes without an IES file are not comparable.

Clause 2 — Simulation report (mandatory)

Supplier shall provide a lighting simulation report (PDF) using the declared optics and the proposed pole layout (height/spacing/placement) demonstrating compliance with project lighting targets.

Clause 3 — CCT & CRI declaration (mandatory)

Supplier shall declare CCT and CRI for the quoted luminaire and disclose the CCT tolerance/range for the delivered batch. If CRI is specified, supplier shall provide the declared CRI level for the configuration.

Clause 4 — Dimming profile disclosure

Supplier shall disclose the dimming method (time/PIR/hybrid) and dimming profile steps used in the simulation and energy budget sheet, as it affects average power (Wavg) and sizing.

Next Steps (Keep Your Project Tender-Ready)

Templates & Evidence

Resources Library — templates, definitions, QC evidence, IES/DIALux workflow.
RFQ & BOQ Kit — copy/paste templates + scoring rubric.
Spec Definitions Hub — normalize Wavg, usable Wh, autonomy, IP/IK, acceptance evidence.
IES & DIALux Resource Center — inputs + deliverables for spacing/uniformity validation.

Shortlist a System Type

Back to All Guides Hub →

Want a quick engineering sanity check? Share your road class, pole height, target lux/uniformity, and worst-month PSH assumptions.

Download: Optics & Spec Worksheet

Get the editable worksheet to standardize optics and prevent non-comparable quotes:

Optics/IES request checklist
CCT/CRI spec template (with tolerances/range)
Simulation request checklist (what the PDF must show)
Quote comparability screening sheet (PASS/FAIL)

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FAQ

Is higher CCT always better for roads?

No. CCT is mainly a visual preference/regulatory constraint. Choose a CCT range suitable for your application and enforce it consistently across bids.

Do I need high CRI for every roadway project?

Not necessarily. Use higher CRI when color identification matters (security/CCTV/pedestrian areas). For standard roads, a moderate CRI requirement can be sufficient if your project does not need detailed color rendering.

Can I compare quotes without an IES file?

No. Without IES photometrics and a simulation PDF for your pole layout, beam distribution and performance assumptions differ, so prices are not apples-to-apples.