Most facility owners discover their EPC partner's weaknesses at commissioning — when delays are expensive and leverage is gone. The right questions, asked before you sign, surface the gaps that a capability statement never will.

  1. Do you self-perform grid interconnection work, or subcontract it? The single biggest cause of commissioning delays in C&I solar is the gap between the EPC contractor and the grid interconnection specialist. If your EPC firm subcontracts HT work, ask to see the subcontractor's track record and understand exactly where accountability ends.
  2. Can you provide a PVsyst simulation file, not just the report? Any firm can produce a PDF yield report. A credible engineering team will share the full PVsyst project file — including loss parameters, soiling assumptions, and horizon shading inputs — so your lender's engineer can independently validate the numbers.
  3. Who provides independent engineering oversight on this project? If the answer is "we handle it internally," ask how they manage the conflict of interest between building the project and auditing its quality. Independent technical review is essential when your capex committee or financier needs assurance beyond the EPC contractor's own sign-off.
  4. What is your BESS integration methodology? There is a significant difference between an EPC firm that sizes a battery based on a client's stated requirements and one that builds a dispatch model from scratch — overlaying generation profiles, tariff structures, and grid code constraints. Ask to see an example dispatch model.
  5. How do you handle DISCOM interconnection approvals? Interconnection delays are not force majeure events — they are predictable. Ask the EPC firm to walk you through the state-specific approval process for your project location and explain what they do to accelerate it.
  6. What does your commissioning package include? A rigorous commissioning process includes: pre-commissioning testing protocols, relay coordination studies, grid synchronisation procedures, string-level IV curve tracing, and a complete set of as-built drawings. Ask for a sample from a recent project.
  7. Can you provide a reference from a similar C&I facility? A project completed for a comparable industrial load profile demonstrates the EPC firm understands your tariff structure, demand patterns, and DISCOM requirements — not just module installation.
  8. What are your HSE metrics from your last three projects? Lost Time Injury Frequency Rate (LTIFR), near-miss reporting rates, and HSE audit scores are objective indicators of site management quality. A firm that cannot produce these numbers has not been measuring them.
  9. How is your EPC contract structured — lump-sum or reimbursable? Lump-sum fixed-price EPC contracts transfer schedule and cost risk to the contractor. Reimbursable contracts transfer that risk back to you. Understand which structure you are signing and what the change order process looks like.
  10. What happens if you miss the commissioning date? Read the liquidated damages clause carefully. Understand the cap, the daily rate, and whether force majeure is defined broadly enough to excuse delays that are actually within the EPC firm's control.

These ten questions will not guarantee a perfect EPC partner — but they will quickly separate the firms that have done this before from those that are learning on your project.