Solar Water Heater Size Calculator (LPD)
Family size and bathing style to litres per day - plus what a solar heater saves you versus the electric geyser.
Your household
Hot water use
Your solar water heater
100 LPD
Recommended size
₹7,656
Saved vs electric geyser / yr
💡 A 100 LPD system covers 4 people with bucket bathing. Against an electric geyser it saves about ₹7,656 a year at ₹8.8/unit - most systems pay back in 3-4 years and last 15+.
ETC (tube) systems suit most of India; go FPC (flat plate) for hard water areas or add a heat exchanger. Winter output drops ~25% in north India.
Frequently asked questions
ETC or FPC collector?
ETC (glass tubes) is cheaper and works in most climates. FPC (flat plate) handles hard water better and lasts longer - pick FPC with a heat exchanger if your TDS is high.
Does it work in winter or monsoon?
Output drops roughly 25% in north-Indian winters; most systems include a small electric backup element for cloudy weeks.