The basic formula
Annual savings ≈ annual units generated × applicable tariff (for units you consume or get credited). Payback ≈ net cost after subsidy ÷ annual savings.
Generation per kW
Across most of India, 1 kW of well-installed panels produces roughly 3.5–4.5 units per day on average across the year – higher in Rajasthan and Gujarat, lower in cloudy or hilly regions. This is an approximation; actual output depends on your location, tilt, shading and weather.
Factors that change real savings
- Tariff slab – higher slabs save more per unit.
- Self-consumption vs export credit rates.
- Fixed charges that remain payable.
- Panel degradation and cleaning frequency.
- Future tariff increases (usually improve the case for solar).
Use our solar calculator for a rough estimate, then ask installers for a site-specific generation estimate.