Geyser vs Solar Water Heater

How the math works

A typical 15-litre electric geyser uses ~2 kWh per bath. For a family of 4 bathing daily that's ~3,000 kWh/year. At ₹8/kWh urban tariff that's ₹24,000/year just for hot water. A 200-litre flat-plate solar water heater (ETC type, MNRE-approved) costs ₹25,000–45,000 installed and replaces 70-80% of that — assuming the cloudy-day electric backup runs for ~60 days a year.

Worked example

Bengaluru 4-person family installs a 200L ETC solar heater for ₹35,000. Old annual geyser cost: ₹18,000. New cost (solar + 20% backup): ₹3,600. Net saving ₹14,400/year → payback in 2.4 years. Over a 15-year lifespan that's ₹1.8 lakh in saved electricity. Mumbai/Pune similar. Delhi pays back in 4 years (more cloudy/winter days). Hill stations (Shimla, Ooty) — skip solar, ROI is poor.

When to use this

• Building a new house or replacing a dying geyser
• Apartment with terrace/roof access and southern exposure
• City with 250+ sunny days/year (most of peninsular and western India)
• Family of 3+ where geyser runs daily

Many states give a 30-40% MNRE subsidy on solar water heaters. Pair with our solar rooftop PV ROI calculator for the full home-energy picture.