A step-by-step guide to calculating rooftop solar project cost in India. Includes ₹/Wp breakdown, GST impact, EPC margins, and a downloadable Excel model.
The Real CFO Story
The CFO of a textile company in Rajasthan was planning a 1000 kWp rooftop solar CAPEX project.
He presented a ₹3.32 crore investment proposal to the board, showing that it could deliver ₹3–4/kWh savings and a strong internal rate of return (IRR). The board liked the numbers but wanted more clarity on one key question:
“How exactly was this ₹3.32 crore project cost calculated?”
They asked:
- What components made up the total cost?
- How was GST factored in?
- Was this benchmarked against current market trends?
To build confidence and win board approval, the CFO reached out to our team at Infinia Solar.
Here’s the exact framework we used to decode the total rooftop solar project cost.
Note: These are indicative market values as of early 2025. Actual prices may vary based on site conditions, structure type, and developer terms.
Component-Wise Breakdown of Rooftop Solar Project Cost
Let’s decode each part of the ₹/Wp cost structure, line by line:
1. Solar Modules – ₹15.00/Wp
This includes 585–590 Wp bifacial N-type panels. They offer higher generation per sq. meter, which improves your project ROI over time.
2. Inverters – ₹2.25/Wp
750 kW string inverters with 33% DC overloading are used. The cost includes inverter protections and basic SCADA.
3. Installation & Commissioning – ₹2.00/Wp
Labour, supervision, and quality checks — from mounting to electrical testing.
4. Cabling – ₹1.50/Wp
Includes both AC and DC cables, considering routing, earthing, and insulation.
5. Structuring – ₹1.00/Wp
Walkways, handrails, and aluminium mounting structures. Weight and wind-load optimized.
6. BoS Charges – ₹3.00/Wp
Balance of System: junction boxes, connectors, cable trays, surge protection devices.
7. Liaising & Metering – ₹1.00/Wp
DISCOM approvals, net metering setup, load enhancement (if required).
8. Project Management Charges – ₹0.75/Wp
Covers site coordination, vendor management, safety compliance.
9. EPC Margin – ₹2.65/Wp
~10% of total EPC — this is the margin charged by most turnkey rooftop EPC providers.
10. GST Impact: ₹4.13/Wp
At 13.8%, GST applies to both goods and services — often overlooked in internal budgets.
Total Project Cost: ₹33.20/Wp or ₹3.32 Cr for 1000 kWp
This is the landed cost including GST — the number most CFOs need when requesting equity approval for a rooftop CAPEX project.
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In a world where ₹/unit savings matter — but project risks matter more — clarity in rooftop solar project cost is non-negotiable.
Whether you’re a CFO seeking board approval or a sustainability head chasing your RE100 goals, this cost breakdown is your decision-making toolkit.