How to Select a Solar EPC Contractor: Tender and RFP Checklist for 2026

Selecting a solar EPC contractor fixes most of a project's construction risk in one signature. Price, programme and performance guarantees are locked in at contract award, and lenders will judge the project partly on who is building it. A disciplined tender produces comparable bids and a contractor your financiers will accept.

This checklist is for developers, project owners and asset managers running a utility-scale solar EPC tender. It assumes you know what an EPC contractor does. If you need the basics first, read our explainer on what a solar EPC contractor is.

In short:

• Run two stages: a prequalification round to cut the field to three to six bidders, then a full RFP with a draft contract.
• Prequalify on comparable MWp delivered, balance sheet, HSE record and lender acceptability, not on price.
• Most utility-scale EPC contracts follow the FIDIC Silver Book logic: lump sum, single-point responsibility, delay and performance LDs, and a performance ratio guarantee.
• Normalise scope gaps before you compare price per Wp.

The solar EPC tender in eight steps

1. Owner's requirements. Technical specification, site data (topographic, geotechnical and hydrological surveys), the grid connection agreement, target COD and your module procurement strategy.
2. Prequalification questionnaire (PQQ) to a long list, typically eight to fifteen firms.
3. Shortlist three to six contractors that pass the gates below.
4. Issue the RFP with the draft contract, specification, pricing schedule and programme template.
5. Site visit and clarifications. Share every answer with every bidder.
6. Bid evaluation, with technical and commercial envelopes scored separately.
7. Negotiation and best and final offer with one or two preferred bidders.
8. Award, with notice to proceed often conditional on financial close.

For a utility-scale project, allow several months between PQQ and signature. Compressing clarifications is where most scope disputes are born.

Prequalification gates for a utility-scale solar EPC

Criterion	Ask for	What good looks like
Track record	Project list with MWp, country, COD and client contacts	Comparable size delivered recently, ideally under the same grid code
Financial strength	Three years of audited accounts	Turnover comfortably above contract value; able to post bonds or a parent company guarantee
HSE	ISO 45001, incident statistics, sample HSE plan	Documented system and compliance with local law, e.g. CDM 2015 in the UK
Quality	ISO 9001, inspection and test plans	Named QA/QC lead, factory and site inspection regime
Bankability	Lender-financed references	Accepted previously by lenders' technical advisers
Insurance	Contractor's all-risk, third-party and PI cover	Limits that match your contract and lender requirements
Supply chain	Sourcing policy, traceability evidence	Can document module origin to cell and polysilicon level

The supply chain gate is no longer optional. Our briefing on solar supply chain due diligence lists the traceability documents to request.

What the RFP pack should contain

• Draft EPC contract in your preferred risk allocation, with bidders asked to submit a deviations register rather than a full mark-up.
• Technical specification: minimum module and inverter standards (IEC 61215, IEC 61730, grid code certification), DC/AC ratio, fixed tilt or trackers, SCADA, security and civil works.
• Interface matrix defining who builds what at the grid connection, including the substation and any work done by the network operator.
• Pricing schedule split into modules, balance of system, civils, electrical and grid works, with unit rates for variations.
• Programme template with key milestones and the long-lead items flagged.
• Performance test procedure referencing IEC 61724-1, with sensor specifications and data-availability rules.
• Optional O&M proposal if you want bundled pricing for the first years of operation.

EPC contract solar terms that matter most

FIDIC Silver Book as the template

The FIDIC Silver Book (EPC/Turnkey Projects) puts design, construction and most ground risk on the contractor for a lump-sum price. That fits project finance, which is why many solar contracts use it or a bespoke form built on its structure. The Yellow Book (Plant and Design-Build) leaves more risk with the employer, notably unforeseeable physical conditions.

Liquidated damages

• Delay LDs, a daily rate sized to cover lost revenue and fixed costs such as debt service.
• Performance LDs, payable if the measured PR falls short, usually calculated from the value of lost energy over the project life.
• Caps: separate caps for delay and performance plus an overall liability cap. These are among the most negotiated terms, and your lenders' adviser will have views on acceptable levels.

Performance ratio guarantee

Set the guaranteed PR from the design's energy simulation with an agreed margin. Test it at provisional acceptance over a defined period with minimum irradiance thresholds, and again at final acceptance after the defects notification period, often two years. Define exclusions such as curtailment and grid outages precisely.

Security package

A performance bond (commonly around 10% of contract price), an advance payment guarantee, retention or a retention bond, and a parent company guarantee where the contracting entity is thin. Add a module price adjustment mechanism if modules are bought after signature.

Evaluating bids like-for-like

Build a scope comparison before looking at price. Price every exclusion and add it back, then convert to €/Wp DC. A design with a higher independent P50 yield can justify a higher capex, so compare on levelised cost or project NPV rather than headline price.

Example weighting (adapt to your project): 40% technical, 45% commercial, 15% contract deviations. Score the programme on realism, not speed.

Red flags include a price far below the field without explanation, refusal to provide audited accounts, unnamed key personnel, module brands described only as "Tier 1", and a deviations register that rewrites the LD regime.

Building your EPC long list on PVFirms

As of October 2026, PVFirms lists 794 companies in its EPC and project developer category, according to its European solar company statistics. Filter the EPC and project developer directory by country and verification tier. Verified firms have had identity, registration/VAT and a live customer confirmed with documents. Premium Partners have also evidenced liability insurance, three or more independent client references and ISO 9001 or equivalent, which saves time in the PQQ.

A directory badge does not replace your prequalification, but it filters out firms that cannot evidence basic registration. For rooftop or small ground-mount work, compare EPC contractors against local installers before tendering.

Frequently asked questions

How many contractors should we invite to a solar EPC tender?

Long-list eight to fifteen for prequalification and shortlist three to six for the RFP. Fewer than three weakens price tension; more than six burdens your team with clarifications and discourages strong firms that see low odds of winning. Tell bidders the shortlist size so they can judge the effort worth investing.

Why do solar projects use the FIDIC Silver Book?

It allocates design and construction risk to one contractor for a fixed price, which is what project-finance lenders want. Owners rarely use it unamended: particular conditions add solar-specific performance tests, PR guarantees, module provisions and grid interface rules. Have counsel experienced in renewable EPC contracts draft those conditions.

Should the owner or the EPC contractor buy the modules?

Owner procurement (free-issue) can cut cost and give control over sourcing, but it shifts delivery, quality and interface risk to you and weakens the contractor's wrap. EPC procurement keeps single-point responsibility at a margin. Many owners pre-negotiate a module supply agreement and novate it to the EPC.

What happens if the plant fails its performance test?

The contractor typically gets a cure period to fix defects and retest. If the plant still falls short, performance LDs become payable up to the agreed cap, and below a minimum threshold you may have the right to reject the works. Make sure the test procedure is unambiguous before signing.

Start your EPC shortlist

Draft your owner's requirements, then build a long list from the EPC and project developer directory and send the PQQ. If the project is still being acquired, our guide to ready-to-build solar projects covers the due diligence that comes first.