How to Compare Solar Quotations Without Getting Fooled

Two quotations for "3 kW rooftop solar, all inclusive" can differ by ₹70,000 and still look identical on a single line. Here is what to compare, line by line.

1. Module make, wattage and certification

Ask for the module brand, wattage, cell technology and whether it is on the ALMM list. Subsidy claims require ALMM-listed modules. Check the module datasheet for the performance warranty and the degradation curve — 25-year warranties typically guarantee about 80–84% output at year 25.

2. Inverter model and warranty

The inverter is the most likely component to fail first. Ask for the model number, the warranty period (5 years minimum, extendable) and the monitoring capability. A generic inverter with no local service presence will cost you weeks of downtime.

3. Structure design and material

Ask for the structure drawing: material, section size, elevation height, galvanising type and corrosion warranty. Undersized structures cause module cracks in the first monsoon; non-galvanised sections rust within two years in coastal Maharashtra.

4. Cable sizing and protection

DC cable should be UV-resistant solar cable of the correct gauge for the string length; AC cable should be sized for the inverter output. Check for DC and AC distribution boxes, surge protection devices, a proper earthing pit and a lightning arrestor. This is the first thing trimmed in cheap quotations and the most common cause of failures.

5. Who handles subsidy and net-metering

Ask in writing whether the vendor files the PM Surya Ghar application, follows up the feasibility approval, and coordinates the net-meter installation — and whether that service is included or billed separately.

6. Service terms after installation

How many cleaning visits are included in year one? What is the response time for a fault? Do they give a written generation estimate, and what happens if generation falls short? A vendor who cannot answer the last question has not designed your system.

Red flags

• Quotations without brand and model numbers.
• Prices far below market — usually achieved by removing protection, structure or cable quality.
• Advance payment demanded before a site survey.
• Pressure to install before feasibility approval "to save time" — this can void your subsidy.

Our quotations always include a full bill of material with brand names, ratings and warranty terms, so comparison is straightforward and unglamorous.