What This Group Covers
That means the questions an EPC should ask are different: not only what the structure costs, but how quickly drawings come back, who signs the tolerance matrix, what happens when the site asks a question at six in the morning, and whether the delivery schedule survives a port delay.
- Procurement criteria and evaluation models for selecting a racking supplier as an EPC
- The difference between an OEM manufacturer and a trading company, and why it matters at construction stage
- Quotation turnaround, drawing responsiveness and technical support during the bid phase
- Lead time commitments, production scheduling and delivery reliability under a fixed programme
- Tolerance interfaces and responsibility allocation between foundation, structure and installation scopes
- Site support: installation guidance, crew training and response when site conditions differ from the plan
Three Configurations to Start From
Three supply relationships cover most EPC requirements:
Transactional line
Structure only, delivered to port, drawings on request. Best for: EPCs with in-house engineering and their own foundation contractor. Relative cost: 1.0 (baseline).
Programme line
Structure plus foundations, reserved production slots, sequencing to construction zones. Best for: EPCs carrying a fixed schedule on a large ground-mount project. Relative cost: +5 to +10% unit price, schedule risk reduced.
Full-scope line
Above plus site support, crew training and installation supervision on the first blocks. Best for: EPCs working in unfamiliar markets or with unproven local crews. Relative cost: +8 to +16% unit price.
Why EPC supply is demanding
The EPC carries the interface risk on a solar project. Every tolerance mismatch between foundation and structure, every drawing that arrives late and every delivery that slips becomes the EPC’s problem, and the recovery cost lands in a fixed-price contract where there is no mechanism to pass it on.
- Bid-stage support is time-critical: a technical clarification that takes a week can cost a tender outright
- Tolerance interfaces between foundation, structure and tracker are a classic responsibility gap, and the EPC pays for it unless it is allocated in writing
- Delivery schedules are committed to the owner before the supply chain is confirmed, so schedule risk sits with the EPC
- Site conditions rarely match the design assumptions, and the supplier’s responsiveness at that point determines whether the programme absorbs the difference
- Materials arriving out of construction sequence idle crews at a cost that dwarfs any unit price saving
- Trading intermediaries add a layer between the EPC and the factory, which slows technical resolution exactly when speed matters most
Engineering Requirements
These are the commitments and capabilities we treat as the basis of an EPC supply relationship, and the criteria we would put in an evaluation model.
- Quotation turnaround commitment, with the technical clarifications answered by an engineer rather than an account manager
- Drawing and calculation pack issued against an agreed date, including the structural basis and the tolerance interface matrix
- Lead time commitment by structure type, with production slots reserved rather than described as indicative
- Tolerance responsibility matrix signed between foundation and structure suppliers, stating correction methods and cost allocation
- Delivery sequencing matched to the construction zone plan, with batch labelling that corresponds to build order
- Site support defined in the contract: installation manual, crew training on the first blocks and a named engineering contact
- Response protocol for site queries, including out-of-hours coverage during installation windows
Selection guidance: ask for the tolerance matrix and a sample drawing pack before award. The speed and completeness of both predict how the project will actually run.
Key Parameters
| Parameter | Typical specification |
|---|---|
| Quotation turnaround | Technical quotation typically 3-10 working days depending on scope completeness |
| Drawing pack | Structural basis, layout drawings, connection details and tolerance matrix issued as a set |
| Lead time | 4-8 weeks standard fixed structures, 8-14 weeks trackers, plus freight and production slot allocation |
| Tolerance allocation | Documented matrix between foundation, structure and installation scopes, signed before fabrication |
| Delivery sequencing | Batch labelling by construction zone, with weekly production visibility during the build |
| Site support | Installation manual, first-block crew training and named engineering contact during installation |
| Query response | Engineering response within one working day, with out-of-hours coverage during peak install |
| Quality evidence | Batch certificates, coating records and dimensional inspection issued with each delivery |
How We Deliver It
- A bid-stage technical service that answers clarifications in days rather than weeks, so the EPC can price confidently and quickly
- A documentation pack issued as a complete set rather than as a sequence of partial submissions, reducing review cycles
- A signed tolerance interface matrix that allocates responsibility explicitly and removes the most common source of EPC loss
- Production slots reserved against the programme rather than quoted as indicative, with weekly visibility through the build
- Batch sequencing aligned to construction zones, so crews receive material in the order they install it
- Site support that includes crew training on the first blocks and a named engineer who answers during the installation window
- Foundation and structure supplied as one scope where the EPC prefers a single interface, removing the classic division of responsibility
Standards and Compliance
- ASCE 7 / EN 1991 / AS-NZS 1170 wind load cases with site-specific terrain categories
- IEC 62727 tracker structural requirements where tracking structures are in scope
- EN 1090-2 or AISC 360 fabrication and execution class documentation
- ISO 1461 hot-dip galvanizing, ISO 9223 corrosivity classification driving zinc mass
- ISO 9001:2015 quality system, ISO 14001 environmental management on request
- Third-party aeroelastic wind tunnel study available for large-format modules
Quality Assurance
Batch documentation is issued per lot: mill certificates traceable to heat numbers, galvanizing records with measured coating thickness, dimensional inspection reports from pre-assembly jigs and hardware lot traceability. Warranty covers named load cases and environmental exposure classes, so claims are settled against data rather than negotiation.
Installation and Site Productivity
Installation speed is designed in, not improvised on site. Pre-assembly ratios are set so the maximum amount of work happens in the factory; parts are kitted and labelled by build sequence so crews never search for components; connection details avoid site welding and minimise the number of distinct fastener types; and adjustment ranges at the interface tolerate the position error that foundation installation inevitably produces. We supply an installation manual with crew sizing, daily output targets and acceptance criteria.
Documentation You Receive
Documentation is built for audits, not decoration: structural calculation notes stating load cases and standards used; foundation design basis mapped to your geotechnical report; material certificates for steel and fasteners; galvanizing certificates with measured coating thickness per batch; assembly drawings with torque tables; and packing documentation matched to container manifests. For financed projects we add lender-format compliance statements; for public tenders we respond to documentation schedules line by line.
Cost and Commercial Considerations
- Engineering and technical support cost is largely fixed and therefore proportionally negligible on large EPC projects
- Reserved production slots add a small premium and remove a schedule risk that is usually worth far more than the cost
- Tolerance interface failures are one of the largest avoidable losses on a fixed-price EPC contract
- Site labour training and supervision typically pays back within the first few hundred kilowatts of installation
- Sequencing failures show up as idle crew days, which typically outweigh any unit price difference between suppliers
Reference Benchmarks
- Middle Eastern and North African projects where single-package pile-and-structure supply removed the tolerance interface between two contractors and compressed the construction programme.
- South-East Asian EPC programmes where batch sequencing to construction zones kept piling crews productive through a weather-constrained schedule.
- European projects where crew training on the first blocks reduced the learning curve and shortened the punch list on a new structure type.
- Latin American projects where a supplier’s ability to answer technical queries during the bid phase was the deciding factor in a competitive tender.
Service Life and Maintenance Planning
Plan maintenance around measurable triggers, not calendar guesses: annual visual inspection of fastener torque samples, coating condition at cut edges and ground-contact zones; a detailed inspection after the first extreme weather year; and re-torque verification after the first thermal cycle on long runs. We supply the inspection checklist and acceptance criteria with the installation manual.
How We Control Delivery
| Stage | What we do | What you receive |
|---|---|---|
| Bid support | technical clarifications answered by an engineer within the agreed turnaround | clarification log and response times |
| Documentation | structural basis, layout and tolerance matrix issued as a complete pack | drawing register and issue dates |
| Production booking | production slots reserved against the programme with weekly visibility | production schedule and progress reports |
| Sequencing | batch labelling and delivery order matched to construction zones | delivery sequence plan |
| Site support | crew training delivered and named engineering contact active | training record and contact protocol |
| Closeout | as-built documentation, warranty register and spares issued | closeout pack |
Send your programme and scope split – we will return a supply proposal with reserved production slots, a tolerance matrix and a delivery sequence plan.
Guides in This Group
Procurement Guide for EPC Contractors
Evaluation criteria, scoring models and the questions that separate suppliers.
OEM Manufacturer vs Trading Company
Why the difference becomes visible in technical response time and tolerance accountability.
Lead Time & Delivery Scheduling
Reserved production slots, sequencing to construction zones and reliability under a fixed programme.
Related Application Directories
This scale band is often combined with the following application groups, which cover terrain, land type and site conditions.
Frequently Asked Questions
How quickly should a supplier respond to bid-stage technical queries?
Should we buy foundations and structure from one supplier?
How do you secure delivery reliability on a fixed programme?
What site support is reasonable to expect?
What happens when site conditions differ from the design assumptions?
What We Need to Quote
- Project programme with construction zone breakdown and required delivery dates
- Scope split: what the EPC performs in-house versus what is expected from the racking supplier
- Site labour cost and availability, plus the equipment available for installation
- Tolerance and interface requirements, including who is expected to correct out-of-tolerance work
Talk to a Structure Engineer
Send your site data, target capacity and construction programme, and our engineers will return a structure concept, a quantity estimate and a costed supply package.
