Solar radiation can be utilised in two basic ways. You can either gain heat from solar thermal collectors or electricity in photovoltaic panels. So far, heating of water by photovoltaics was too expensive to compete with conventional solar thermal collectors.
Weight , durability , and currently even the price of solar thermal collectors is comparable with commercially available photovoltaic modules.
Annual energy yield per unit area is approximately twice in the solar thermal collectors compared to the highest quality photovoltaic modules with cells made of monocrystalline silicon, due to the higher efficiency.
In the summer the photovoltaic modules are better when the working fluid is heated to temperatures above 100 °C. In the winter the breaking point is about 40 °C. The advantage of photovoltaics is the absence of heat transfer fluid and easier transfer of energy produced to the point of use. Electricity can also be used more versatile than heat.
If the investment cost of a complete solution of heating water by electricity from photovoltaic panels, either directly or using a heat pump, is lower than the investment cost of the solar thermal system, the PV water heating can be considered as effective utilization of electricity from photovoltaic plants. Such a solution could then be included as an alternative to any grant support for solar water heating.