Solar Water Heating

Between 2007 and 2015, Sisyan has developed a variety of efficient solar water heating systems. Designs include flat plate and vacuum tube collectors. However, we believe that the declining cost of solar panels makes these technologies nearly obsolete.

Since August 2014, Sisyan has been testing a low voltage design using photovoltaic (PV) panels to heat water in a well-insulated tank with a heat exchanger.

Using PV panels eliminates the freezing, overheating, and maintenance issues associated with pumping fluid to the roof that has kept solar thermal from widespread adoption.

In 2012, Mark Holladay of Green Building Advisors predicted correctly the decline of flat plate and VT solar hot water collectors. With the recent 70% drop in the cost of PV panels, Photovoltaic Domestic Hot Water (PVDHW) has become the preferred solution. Advantages include less maintenance, faster installation time, overlap with PV industry, and lower cost. Sisyan, LLC has designed, prototyped and tested extensively 4 such installations.

Below is a detailed description of the key components:

We recommend a tank capacity of 1.1 m3 for a single family home. The insulation should be 25-35R. Since the maximum water temperature will be below 60C, roto-cast technology is recommend for the tank.


Heat Exchanger – HX

The heat exchanger is made out of 50m of CT SS 316L, 1” diameter tubing.


Tubular Heat Element -30 VDC/250W

Electrical Controls

SRCC testing has been initiated and the certification is forthcoming.

The maintenance of the system is low since there is no risk of freezing or over-heating. There are no inverters, high voltage connections, pumps, circulators or booster pumps.

Yan KunczynskiFounder / Designer
Benjamin BurgerDirector of Product Deployment