Solar water heaters are sized in LPD — litres per day: the amount of hot water (around 60 °C) the system delivers on a typical sunny day. Choosing the right capacity is the single most important decision for comfort and value.
The simple rule
Plan for 35–50 litres of hot water per person per day for bathing. Hot water at 60 °C is mixed with cold water, so actual usage at the tap is higher than the LPD rating.
Quick sizing table
| Family size | Bathrooms | Recommended capacity |
|---|---|---|
| 2–3 people | 1–2 | 100 LPD |
| 3–4 people | 2 | 150 LPD |
| 4–5 people | 2–3 | 200 LPD |
| 6–8 people | 3–4 | 300 LPD |
| Large villa / joint family | 4+ | 500 LPD or two systems |
| PG / hostel (per 10 residents) | — | ~500 LPD |
Adjust for these factors
- Rain showers & bathtubs use 2–3× more water — size up.
- Kitchen & washing machine hot water lines need extra capacity.
- Elderly members or infants often mean more frequent hot water use.
- Distance from tank to bathroom — long pipes waste hot water; consider insulation.
Use our free hot-water calculator or get a recommendation from an expert.
Get Free QuoteETC or FPC?
In Bangalore, most homes use borewell or mixed water with high hardness. FPC (flat plate collector) heaters handle hard water much better than ETC glass tubes, which scale up and lose efficiency. If your water is soft (Cauvery supply), ETC offers great value. Read our detailed ETC vs FPC comparison.
Roof space needed
A 100 LPD system needs roughly 2 m × 2 m of shadow-free roof facing south. 200–300 LPD systems need 4–6 m². Ensure the tank stands higher than the bathroom outlets, or add a pressure pump for good flow.
Frequently Asked Questions
Is a bigger solar water heater always better?
No. An oversized system costs more and the extra hot water cools down unused. Size to your real daily use.
Can I connect a solar water heater to all bathrooms?
Yes, with proper plumbing. For multi-floor homes, a pressure pump keeps flow strong.
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Get Free QuoteDisclaimer: prices, tariffs and subsidy figures are indicative and based on publicly available information at the time of writing; they can change. Contact us for current, site-specific figures.
