Buyer's guide
How to evaluate solar EPC proposals — the sizing, the structure, the approvals and the guarantee
Two solar proposals at the same rupees per kilowatt can be very different plants. This checklist tests the proposal's engineering before its price; the guide to selecting a solar EPC contractor tests the contractor behind it.
Last reviewed · Reviewed for checklist content, linked standards Authority names, portals, fees and timelines change with state notifications; confirm the live position with the authority before relying on it.
What to check
- Capacity basis — sized to consumption and sanctioned load, or to the roof
- Yield estimate — irradiance source, losses, performance ratio, and whether it is guaranteed
- Module — make, model, wattage, technology, ALMM listing where required
- Inverter — make, string or central, MPPT arrangement, grid-protection compliance
- Structure — type, wind-load design, roof loading, stability certificate
- Approvals — net-metering and CEIG as applicant, or by client
Documents to request
- Shadow analysis for the site
- Yield estimate with assumptions
- Module and inverter datasheets and certificates
- Structural design summary
- Single-line diagram with protection
- Draft O&M scope and performance report format
Technical questions to ask
- What happens to export at our tariff, and did the savings assume every unit displaces a retail unit?
- What is the DC/AC ratio and why?
- How is the array earthed and surge-protected?
- What monitoring level — plant, inverter, string?
- What roof repair or strengthening does the proposal assume?
Commercial questions to ask
- Price per kWp on what module wattage and count?
- What is excluded — approvals, metering, monitoring, structural certificate, roof works?
- Performance guarantee: figure, measurement method, remedy
- Warranty terms and who holds them
- O&M cost and term
Hidden scope gaps to look for
- Net-metering "by client"
- Structural certificate excluded
- Roof strengthening excluded
- Monitoring excluded
- Non-ALMM modules where ALMM is required
- Sanctioned load ignored
Commissioning documentation to insist on
- Module serial schedule by string; string tests; inverter settings; array earthing test; stability certificate; DISCOM inspection report and approval; monitoring access
Warranty and AMC terms to review
- Module performance and product warranties; inverter warranty; workmanship warranty
- O&M with cleaning frequency, servicing, string monitoring, PR reporting and response times
Safety and compliance issues that matter
- IEC 61215/61730, IEC 62109, ALMM where required
- CEIG at HT or above the state's threshold; DISCOM connection standard
- Roof-edge and fall-arrest during installation
How Secured Engineers can help
Secured Engineers Pvt. Ltd. reviews solar proposals against this checklist as part of a technical review, and prepares its own on the same basis — sized to consumption and sanctioned load, with the structure designed for the roof and the approvals filed as applicant.