PV modules
Dedicated modules converted sunlight to DC electricity without a solar-fluid loop.
Photovoltaic water heating · system context
Sunlight.
Stored as hot water.
PVDHW shows a simple path from photovoltaic modules to low-voltage resistance elements in a large, well-insulated water tank—using thermal storage instead of batteries for a specific household load.
Informed by four documented installations · Reviewed July 19, 2026
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Direct answer
What does PVDHW mean?
PVDHW stands for photovoltaic domestic hot water. In the Sisyan system, dedicated PV modules supplied low-voltage electricity to resistance elements that warmed a large insulated storage tank. A heat exchanger transferred that stored heat to domestic water.
The PVDHW system
Four parts, one energy path
Electrical control
Low-voltage controls switched power to the heating elements and managed temperatures.
Insulated tank
A large water volume stored heat across cloudy periods and daily demand cycles.
Heat exchanger
A separate potable-water pathway collected heat from the storage volume.
2026 perspective
The concept is plausible. The choice is not automatic.
Direct PV resistance heating can be electrically simple and turns water into a flexible thermal load. But heat-pump water heaters usually deliver more heat per unit of electricity, grid-connected PV can serve many household loads, and solar thermal remains viable in the right climate and application.
Compare the tradeoffs with no sales pitch →System details