Most procurement teams compare unit price.
Tender reviewers and finance teams compare 5-year total cost of ownership (TCO) — and the decision often changes.
This guide gives you a tender-auditable 5-year TCO template for Solar Street Lighting vs Grid Street Lighting, plus the engineering assumptions that decide the numbers (spacing, optics, maintained lighting, O&M, replacements). It is written for EPC teams, tender reviewers, and finance/procurement stakeholders who need a defensible and auditable comparison.
Internal links
- Engineering deliverables hub: Engineering Support Hub
- Reference projects (budget sanity check): Projects
- System types & use cases: Solutions
Primary CTA (1/3)
- Under deadline? Request Engineering Pack (24H) →
Quick Answer (60 seconds)
To compare Solar vs Grid lighting fairly over 5 years:
1) Lock the same lighting targets (Avg / Min / Uniformity) and verify with DIALux/Relux
2) Use maintained lighting assumptions (not day-one). State the maintenance factor clearly
- Example only (must be stated & agreed): LLD × LDD = 0.81
- Always follow the tender/owner requirement if specified
3) Run spacing sanity checks early — practical spacing often does not exceed ~5–6× mounting height unless photometry/uniformity proves it
4) Include real drivers: cabling/trenching + connection/meter fees + outages (grid) vs battery replacement + cleaning/inspection (solar)
5) Add sensitivity checks: battery replacement year, tariff escalation, trench length per pole, theft/vandalism risk
If you don’t lock lighting + geometry first, your “TCO” is just a spreadsheet story.
Reviewer note (cold warning):
If the tender document does not explicitly state the uniformity definition (Emin/Eavg or Eavg/Emin), reviewers typically interpret it in the strictest way, which often leads to unexpected failures during technical evaluation.
Need the full tender submission checklist (BOQ + IES + attachments)?
→ Solar Street Lighting Tender Pack Checklist →
Why engineering assumptions dominate TCO (not lamp wattage)
Your 5-year cost is driven by how many poles and luminaires you need — and that comes from:
- Optics selection and distribution match (Type II / III / IV)
- Spacing and whether uniformity passes
- Maintained lighting (LLD/LDD or MF), not initial values
- Uniformity definition is tender-specific
- Tenders may use Uo = Emin/Eavg or Uniformity = Eavg/Emin (and sometimes other definitions)
- We follow the tender’s required definition and state it explicitly on the assumptions page
Key insight: Optics → feasible spacing → pole quantity → CapEx/OpEx → TCO
Pole quantity is the fastest way to change a 5-year TCO.
That’s why a TCO sheet should link to IES/LDT + DIALux/Relux outputs + BOQ mapping — otherwise reviewers can’t audit it.
Evidence links
- Photometry: IES/LDT Photometric Files
- Simulation outputs: DIALux Simulation Outputs
- Traceability method: BOQ Mapping (Auditable)
Optics choice affects spacing → pole qty → CapEx/OpEx, so it directly impacts TCO.
The 5-Year TCO Template (Copy/Paste Tables)
Below are copy-paste tables you can recreate in Excel quickly.
(If you prefer the editable Excel file, request it in the engineering pack.)
Table A — Inputs (Assumptions Page)
| Item | Value | Notes (must be stated) |
|---|---|---|
| Country / City | Tariff, corrosion/dust, theft risk | |
| Road width (W) / lanes | Drives optics & spacing | |
| Pole arrangement | Single / opposite / staggered / median | |
| Mounting height (H) | m | |
| Arm length / overhang | m | |
| Tilt limit | 0° | Unless tender allows otherwise |
| Lighting targets | Avg / Min / Uniformity per tender | |
| Uniformity definition | Tender uses Emin/Eavg or Eavg/Emin (state which) | |
| Operating hours | h/night | |
| Dimming policy | Profile or “full output” | |
| Maintained factor (MF) | Example only: LLD×LDD=0.81; use tender/owner agreed | |
| Energy tariff | $/kWh + escalation % | |
| Trenching/cabling/reinstatement cost | $/m + trench length per pole (estimate) | |
| Connection / meter fees | Utility & service fees | |
| Maintenance visit cost | $/visit | |
| Replacement assumptions | Battery year / driver rate | |
| Evidence refs | IES filenames + DIALux page refs | |
| BOQ mapping ref | BOQ line ↔ model code ↔ IES ↔ DIALux |
Table B — Quantity Model (Auditable)
Option A (recommended): derived from DIALux/Relux
| Output | Solar | Grid | Evidence |
|---|---|---|---|
| Pole qty | DIALux report page __ | ||
| Spacing (m) | Layout evidence | ||
| Optics type | IES/LDT filename | ||
| Pass/Fail | Avg/Min/Uniformity per tender |
Option B (early sanity check): illumination method spacing estimate (check only; final must pass uniformity by simulation)
Spacing estimate:
Spacing = (LL × CU × LLD × LDD) / (Eh × W)
Sanity rule: practical spacing often does not exceed ~5–6× mounting height unless photometry/uniformity proves it.
Reviewer note (cold warning):
Spacing proposals that exceed ~5–6× mounting height without clear photometric justification are commonly flagged for clarification, delay, or outright rejection — even if average lux appears acceptable.
Table C — 5-Year Cost Summary (Solar vs Grid)
| Cost bucket | Solar (Year 0–5) | Grid (Year 0–5) | Notes |
|---|---|---|---|
| CapEx – Luminaire/system | Solar: PV+battery+controller; Grid: luminaire only | ||
| CapEx – Pole/foundation/civil | Similar scope; depends on foundation standards | ||
| CapEx – Cabling/trenching/reinstatement | Grid-heavy variable | ||
| CapEx – Connection/meter/utility fees | Grid-heavy variable | ||
| OpEx – Energy | Grid-heavy variable | ||
| OpEx – Cleaning/inspection | Solar cleaning varies by dust | ||
| OpEx – Maintenance visits | Labor/vehicle assumptions | ||
| Replacements – Battery/driver | Biggest mid-life swing factor | ||
| Total 5-Year TCO | Must be auditable |
Table D — Sensitivity (What can flip the result)
| Variable | Low | Base | High | Notes |
|---|---|---|---|---|
| Tariff escalation (%/year) | Grid TCO sensitive | |||
| Trench length per pole (m) | Grid CapEx sensitive | |||
| Trenching+reinstatement ($/m) | City standards can dominate | |||
| Battery replacement year | Solar mid-life swing | |||
| Maintenance visits/year | Access + dust + policy | |||
| Theft/vandalism risk cost | Localized but real |
Secondary CTA (2/3)
Want the editable Excel template + assumptions page format (reviewer-friendly)?
✅ Request Engineering Pack (24H) →
CapEx Checklist (Solar vs Grid)
Solar CapEx (typical)
- Solar system (luminaire + controller + PV + battery)
- Pole + bracket + foundation
- Civil installation
- Optional: monitoring/IoT platform
Key drivers: Grid often dominated by trenching/cabling + connection; Solar dominated by battery replacement + O&M schedule (project-dependent).
Grid CapEx (typical)
- LED luminaire
- Pole + bracket + foundation
- Cable + conduit + trenching + backfill + reinstatement
- Distribution cabinet / protection
- Connection & meter fees
- Installation + commissioning
Tender note (often underestimated): reinstatement can exceed luminaire cost in urban projects (asphalt cutting, concrete repair, traffic control, city standards).
Reviewer note (cold warning):
In urban grid projects, reinstatement and traffic management costs are frequently audited as standalone items. If they are missing or under-scoped, the financial comparison may be deemed non-compliant, regardless of luminaire price.
OpEx (Year 1–5)
Solar OpEx (typical)
- Panel cleaning
- Inspection visits
- Minor parts replacement (controller/driver)
- Battery replacement (largest mid-life driver)
Grid OpEx (typical)
- Energy consumption
- Meter/service fees
- Outage response / emergency repairs
- Driver replacements as needed
5-Year Summary (TCO + Payback)
For each option:
TCO(5y) = CapEx + Σ(OpEx Year 1..5) + Σ(Replacements) − Residual value (optional)
Recommended outputs:
- Total 5-year cost
- Cost per pole per year
- Cost per km per year (if road length known)
- Payback point (via cumulative cost chart)
Cumulative cost over 5 years: the payback point appears when the lines cross (example only — depends on tariff, trench length, maintenance, and replacement assumptions).
A Tender-Safe “Assumptions Page” (Add to the submission)
Reviewers love a one-page assumptions summary.
One-page assumptions note makes the TCO auditable: geometry + optics + maintained factor + IES/DIALux references.
Include:
- Geometry (W, H, spacing, pole arrangement, tilt)
- Optics type used (Type II/III/IV)
- Maintained factors (LLD/LDD or MF)
- Uniformity definition (per tender)
- IES/LDT filenames and DIALux/Relux report page references
This is the difference between a “finance spreadsheet” and an auditable tender evidence pack.
E-E-A-T boundary statement (recommended)
- We do not publish “guaranteed savings” claims without agreed inputs.
- All results depend on tender targets, geometry, civil conditions, tariffs, and agreed replacement/O&M assumptions.
- If the tender specifies parameters, those override example assumptions.
The 5 biggest TCO mistakes (and how to avoid them)
1) Comparing different lighting performance
If one option is brighter or has better uniformity, the TCO comparison is invalid.
2) Using day-one output only
State maintained assumptions and make them tender-safe (example factors must be labeled and agreed).
3) Over-promising spacing
Spacing beyond ~5–6× mounting height triggers reviewer questions unless photometry/uniformity proves it.
4) Ignoring grid civil works
Trenching, reinstatement, permits, and connection fees can dominate grid CapEx.
5) Forgetting replacements
Battery replacement (solar) and driver replacements (grid) can flip the 5-year result.
What we deliver (so your TCO becomes reviewer-proof)
If you send:
- road geometry + targets (Avg/Min/Uniformity per tender)
- BOQ (even draft) + site plan/drawings
- tariff + trenching/cabling/reinstatement cost (if available)
We return:
- 5-year TCO sheet (Solar vs Grid) + assumptions page
- matched IES/LDT + optics/spacing notes
- DIALux/Relux outputs with page references
- BOQ mapping annex (BOQ ↔ IES ↔ DIALux)
5-Year TCO Analysis Input Sheet (Inputs Needed)
Send these inputs and we can run a tender-ready 5-year TCO with an auditable assumptions page (24H response).
To build a tender-auditable 5-year TCO comparison (Solar vs Grid street lighting), share the inputs below.
If you don’t have some items, leave them blank — we can propose assumptions and mark them clearly.
1) Project Overview
- Country / City: ____
- Project stage: Feasibility / Budgeting / Tender / Implementation
- Road category / standard used (if any): ____
- Required documents: TCO sheet / DIALux/Relux / BOQ mapping / IES files / Others: ____
2) Road Geometry (needed for pole quantity & spacing)
- Road width (W): m (or lanes: )
- Pole arrangement: Single-side / Double-side (opposite) / Double-side (staggered) / Median
- Mounting height (H): ____ m
- Arm length / overhang: ____ m
- Target spacing range (if defined): ____ m (or “optimize by simulation”)
- Tilt limit: 0° / up to ____° (tender requirement)
3) Lighting Targets (tender performance)
- Avg lux: ____ lx
- Min lux (if specified): ____ lx
- Uniformity requirement: ____ (state definition per tender: Emin/Eavg or Eavg/Emin)
- Operating hours per night: ____ h
- Dimming policy: ____
4) Grid cost inputs (CapEx + OpEx)
- Energy tariff: ____ $/kWh
- Tariff escalation (annual): ____ % (optional)
- Meter/service fees: ____ $/month (optional)
- Trenching + cabling + reinstatement cost: ____ $/m
- Estimated trench length per pole (or per km): ____ m (optional)
- Distribution cabinet / protection / breakers: ____ $ (estimate)
- Transformer / connection / utility fees: ____ $ (estimate)
- Maintenance visit cost: ____ $/visit
5) Solar cost inputs (CapEx + OpEx)
- Autonomy requirement: ____ nights
- Battery replacement assumption: replace in year ____ (project-dependent)
- Panel cleaning frequency: ____ times/year
- Site risks: theft / vandalism / coastal corrosion / desert dust: ____
- Monitoring requirement: None / 4G / LoRa / other: ____
6) Project scale
- Total road length: ____ km
or - Total pole qty (if already defined): ____ poles
What you will receive (Tender-Ready Output)
After receiving your inputs, we can provide:
1) 5-year TCO sheet (Solar vs Grid) with clearly stated assumptions
2) Cumulative cost chart + payback point
3) Optics + spacing recommendation (Type II/III/IV impacts pole qty and TCO)
4) DIALux/Relux outputs (targets + uniformity) + IES/LDT references
5) BOQ mapping annex (BOQ ↔ model code ↔ IES filename ↔ DIALux page reference)
Under deadline? Send just road width + mounting height range + energy tariff (and trenching cost if available).
We deliver an auditable 5-year TCO pack (assumptions page + cost sheet + payback chart) within 24 hours.
Legal / Responsibility Boundary (cold warning)
Responsibility note:
This TCO template and any example factors are provided for tender evaluation only. Final pricing, acceptance, and project responsibility depend on tender-approved inputs and signed BOQ/scope. Any changes to geometry, civil scope, tariffs, or replacement/O&M policy after approval will invalidate the comparison unless re-audited and re-approved in writing.
FAQ
Does this replace a DIALux/Relux report?
No. A TCO template is defensible only when quantities + performance are proven by a lighting report.
What if tariffs or battery life are unknown?
Use ranges and run sensitivity (battery replacement year, tariff escalation, trench length per pole, maintenance frequency).
Can I use one optic type everywhere?
Not safely. Optics must match road geometry and arrangement. Using one optic type often forces either over-brightness (waste) or uniformity failure (rejection). We recommend selecting optics per road type and proving it via IES + DIALux/Relux.
Final CTA (3/3)
Under deadline? Send just road width + mounting height + tariff.
✅ Request Engineering Pack (24H) →
