Solar water heating: hot water without the electricity bill
Water heating is one of the largest single loads in a typical home. A solar water heater removes it, and it is the simplest solar product to own, because there is almost nothing to operate.
Why heating water with sunlight beats heating it with electricity
An electric geyser converts electricity into heat. A photovoltaic panel converts sunlight into electricity, which you would then convert into heat, losing energy at every step. A solar thermal collector skips the intermediate stage and heats the water directly, which is why it does the job with far less roof area than PV would need for the same result.
For a household whose bill is driven mainly by a geyser, this is usually the cheapest effective intervention available, and it does not require a DISCOM application or a metering change.
ETC or FPC: the actual difference
| Aspect | Evacuated tube (ETC) | Flat plate (FPC) |
|---|---|---|
| How it collects heat | Rows of double-walled glass tubes under vacuum. The vacuum is the insulation. | A flat insulated box with an absorber plate under toughened glass. |
| Cold-weather performance | Better. The vacuum loses very little heat to cold air. | Loses more heat to the surroundings on cold mornings. |
| Durability | Glass tubes can be broken by hail or impact, but are individually replaceable. | More robust as a unit. Fewer things to break. |
| Hard water tolerance | Scale builds inside the tubes and is harder to clear. | Generally handles hard water better and is easier to service. |
| Typical cost | Usually the lower-cost option for the same capacity. | Usually higher for the same capacity. |
Neither type is universally better. We recommend based on your water quality, your roof and how much hot water you actually use.
Sizing your system
Solar water heaters are specified by storage volume in litres per day (LPD), sold in standard sizes — typically 100, 150, 200 and 300 LPD. The right figure depends on how many people use hot water, how many bathrooms are in use at once, and whether hot water is needed for anything beyond bathing. As a rough starting point, a 100 LPD unit suits a small household, and larger homes or those with more than one bathroom in simultaneous use typically move to 200 LPD or above — but the correct size for your property depends on your actual usage, not a household-count rule of thumb alone.
Keeping it working
Solar water heaters fail quietly. A scaled collector or a leaking tank does not announce itself: the water simply gets less hot over a period of months, and households compensate by switching the backup element on more often, which defeats the point of having bought the system.
Periodic descaling and inspection are covered under our maintenance and AMC plans. If you would like a recommendation for your property, get in touch with your household size and location.
Common questions
How does a solar water heater work?
A collector on the roof absorbs sunlight and transfers that heat directly into water, which is stored in an insulated tank. In most domestic systems the water circulates by thermosiphon (heated water rises into the tank on its own), so there is no pump and nothing to run.
Which is better, ETC or FPC?
Evacuated tube collectors are usually cheaper and perform better in cold conditions. Flat plate collectors are more robust and cope better with hard water. In most of Telangana and Andhra Pradesh, water hardness is the deciding factor more often than temperature.
Do I still need an electric geyser?
Most systems include an electric backup element for long spells of overcast weather or unusually heavy demand. In normal conditions it stays off. Keeping the backup is about certainty of hot water, not about routine use.
Does a solar water heater qualify for the PM Surya Ghar subsidy?
No. PM Surya Ghar applies to rooftop solar photovoltaic systems that generate electricity. A solar water heater is a thermal product and sits outside that scheme, though other state or institutional incentives have applied to thermal systems at various times.
What maintenance does a solar water heater need?
Keeping the collector surface clean, and periodic descaling where the water is hard. Scale is the most common cause of a system that has quietly stopped performing, and it builds up gradually enough that owners rarely notice until output has fallen a long way.
Get a solar water heater quote
Tell us your household size and where the property is. We will recommend a collector type and capacity, and quote for supply and installation.