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
Approvals — net-metering and CEIG as applicant, or by client
Put two quotations side by side — the same scope, line by line
Capacity and its basis — kWp DC (module nameplate) or kW AC (inverter rating); a 'kW' price on different bases is not comparable
Tax basis — excluding or including GST; convert both to the same basis before comparing totals
Cable scope — DC and AC runs, sizes and routing allowance; who supplies the cable trays
Grid interface — LT or HT connection, protection and metering, and any transformer or bay work — included, excluded or 'by client'
Generation assumption — units per kW per year, the loss allowance, and how much is self-consumed versus exported under your DISCOM's settlement rules
Makes, structure, approvals, warranties and aftercare — compare them on the checklist above, but write each quotation's answer in the same row so the gaps show
Exclusions — the full list, read item by item; a missing exclusion line is a question, not a saving
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?
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.
Put them on the same scope before comparing the price. Check that both state capacity on the same basis (kWp DC or kW AC), the same tax basis, the same structure and cable scope, the same grid-interface work and the same approvals responsibility, and read each exclusions list line by line. Then compare the generation assumption, including how much of the output each proposal assumes you consume rather than export. Only then is the price per kW meaningful.
What is the first thing to check in a solar EPC proposal?
The capacity basis. If the proposal sizes the plant to the roof rather than to your consumption and sanctioned load, the savings it projects assume export at a tariff you may not get, and the net-metering capacity may be capped. Everything else follows from getting this number right.
Comparing contractors or quotations?
Send what you have. An engineer reviews it against these checks and replies with what is missing.
