Integrate the two systems means saving on average 50% of gas consumption and improve the functioning of the panels. If you can not connect to the gas existing in the tank then you need to insert an electrical resistance of at least 1 kw with thermostat set at 40 degrees centigrade.
It is really simple: solar panels (or solar collectors) runs a special liquid exposed to the sun warms up. Inside the dwelling is installed an electronic control that simultaneously measures the temperature of the liquid and the temperature of the water contained within a thermally insulated tank. When the liquid in the panels is more hot water activates a circulation pump that brings the liquid to a heat exchanger inside the tank. Here is the exchange of heat and water warms up. Depending on the temperature that the water reaches undergo a stratification and then will be sent to the radiators or to the taps. The pump runs until the liquid collector is hotter than the water of the tank.