How to Compare Solar EPC Quotes for a 500 kW Plant: A Line-Item Checklist

To compare solar EPC quotes for a 500 kW plant, put every bidder against the same written scope and compare line by line: module make and wattage, inverter class, structure and wind design, cable sizes, earthing, HT works, approvals, civil works, monitoring and year-one maintenance. Most 20% gaps come from scope, not margin. The published C&I band of ₹24,000–32,000 per kW ex-GST puts 500 kW near ₹1.2–1.6 crore.

Start with a common scope

Quotes are only comparable if every bidder has priced the same plant. Send one document: your last twelve electricity bills, sanctioned load or contract demand, roof drawing with sheet type, the point of interconnection and any restrictions on working hours. Our RFQ page shows the format. Ask bidders to submit prices in your schedule, not in their own layout.

The line-item comparison

Use this table as the cover sheet for your bid comparison. Fill it for each bidder.

See also our guide on evaluating solar EPC proposals.

Modules: wattage and ALMM status

Ask for the make, model and rated wattage, not just 'mono PERC' or 'TOPCon'. Check whether the module is on MNRE's ALMM list where the scheme or approval requires it, and whether the quote means DCR modules for any subsidy route. See our ALMM and DCR explainers. A quote with 545 Wp modules and one with 580 Wp modules cannot be compared by module count.

Inverters, structure and cables

Inverter architecture is a design choice: many string inverters or fewer central units. It affects serviceability, shading tolerance and replacement cost; read string versus central inverters before you decide.

For structure, ask for the design wind speed, steel grade, coating and roof fixing method. For cables, ask for core size and the route length, because a long run to the interconnection point can add cost and loss. If a bidder will not state these, the saving is hidden somewhere else.

Which exclusions move the price most?

• HT interconnection: transformer, HT panel, metering cubicle and cable.
• Roof strengthening or re-sheeting where the existing roof cannot carry the load. Check with the roof load calculator.
• DISCOM-side charges and inspection fees.
• Long cable routes to the point of connection.
• Monitoring, cleaning and the first year of maintenance.
• Taxes: confirm whether prices are ex-GST or inclusive.

Use a calculator to check, not to decide

Run your bill through the solar calculator for an independent size and cost check, and use the quotation comparison calculator to keep the line items side by side. A quote that is far below the band needs a question; a quote above it needs a reason.

Commercial terms that change the real price

Two quotes with the same equipment can still differ in what you finally pay. Compare payment milestones: a bidder who asks for most of the money before delivery carries less risk than you do. Compare the warranty terms as written: module product and performance warranty, inverter warranty period and who handles claims. Compare the defect liability period and the performance commitment, if any, and ask how generation is measured. If a bidder offers a performance guarantee, ask what it is measured against and what happens if the plant falls short.

Also compare the delivery schedule and what the bidder assumes about your site: working hours, crane access, power and water for construction, and who provides safe storage. A short schedule that assumes you will clear the roof first is a risk you have not priced.

A simple scoring method

Once the line items match, score each bidder on price, technical fit, approvals scope, schedule, references you can visit, and commercial terms. Weight price at no more than half. Visit one operating plant of similar size for each shortlisted bidder and ask the owner about generation, faults and service response. Our guide on selecting a solar EPC contractor covers the reference check in more detail.

Red flags in a solar quotation

Some patterns repeat across quotations that later cause trouble. A price that is quoted per kW without a stated module wattage hides the real plant size. A bill of quantities with a single lump sum for 'balance of system' gives you nothing to compare or audit. A generation estimate with no stated assumptions, such as tilt, losses, degradation and shading, is a sales number and not an engineering one. A schedule that omits DISCOM approval time assumes the utility will act on the bidder's timetable.

Ask each bidder for a single-line diagram, a layout drawing, equipment data sheets and a generation estimate with its assumptions. Four documents, and you can tell a prepared bidder from an improvised one.

How Secured Engineers helps

We can review quotations you already hold, including from other bidders, and point out scope gaps before you sign. Design is done in-house, and approvals (Fire NOC, CEIG, DISCOM net-metering) are filed in-house. Mechanical, electrical, plumbing, fire and solar work can sit under one contract. We work from offices in Noida and Ludhiana, with 535+ projects across 18+ states and 89.77% repeat clients.

If you have a bill, a drawing or quotations in hand, send them and we will tell you what is missing. See RFQ page, message us on WhatsApp, call +91 70099 85817, or ask for a free quote.