Circulation Pumps for Solar Water Heating Systems

Solar systems for water heating cannot function without a pump that ensures the circulation of water to and from the solar panel. Discover how solar water heating systems work, why pumps are their key component, and how to correctly choose a solar pump.

How Solar Water Heating Works

Solar water heating, or photothermal systems, is a modern, eco-friendly, and cost-effective way to ensure water heating for both households and commercial properties. However, it is not the same as water heating using photovoltaics, although these two terms are often confused.

1. Water heating using photovoltaics means that heating is provided by a conventional electric boiler, which is not powered by the public electricity grid but by local photovoltaic panels. Photovoltaic panels convert solar energy into electricity, which then powers the boiler.
2. Solar water heating is provided by collectors, usually placed on the roof of the building, where they capture rays and convert them into heat. Collectors are available in flat and tubular designs. The system also includes piping with a heat transfer fluid, a circulation pump, a water storage tank, and other components. The heat is transported via the heat transfer medium in the piping to a coil in the tank, where it heats the water. The heated water is then distributed from the tank to the building. These systems convert solar energy directly into heat (i.e., without using electricity).

Water from solar heating can be used not only as hot water from the tap but also for supplementary heating in water heating systems (both underfloor and radiator) or for heating pool water. Given the climatic conditions in the Czech Republic, this system can only be used for heating during transitional periods, i.e., in spring and autumn months.

A properly designed and suitably located solar water heating system can cover almost the entire water heating demand in a household from spring to autumn. During winter, it covers about 25% of the demand, so it is always necessary to install an additional source, such as a boiler. Apart from the initial and maintenance costs of the system, you don't have to pay anything – the system uses solar energy, which is completely free. Moreover, the operation of the solar system is almost emission-free.

Circulation Pumps for Solar Water Heating and Heating Systems

As evident from the description of the photothermal system's operation, circulation pumps are an integral part of them because they ensure the flow of fluid in the system. However, not just any circulation pump can be chosen for solar water heating.

Solar pumps are compared to regular circulation pumps designed for higher fluid temperatures, which they can withstand, and can also be used for glycol mixtures, which are used in solar systems. Such pumps are manufactured by brands like Grundfos and Wilo, which guarantee long life and high quality.

How to Choose a Solar Pump

Circulation pumps are electronic devices, and their correct selection is very important for the highest possible efficiency of the photothermal system. The key parameter when choosing is the maximum temperature of the pumped fluid, which should be at least 95 °C, and the possibility of use for glycol mixtures. Additionally, focus on:

• the type and dimension of the pump connection,
• the pump's delivery head,
• the pump's performance or discharge,
• the method of performance regulation.

NOTE: The term solar pumps often refers to ordinary pumps that use solar energy for their operation. However, these pumps are not suitable for photothermal systems.

Solar circulation pump WILO

Solar Circulation Pump WILO Varios PICO STG

For solar water heating systems, energy-efficient circulation pumps from the WILO Varios PICO STG product line are suitable. Individual pump models are designed for a pumped medium temperature of 95 °C or 110 °C, meeting the requirements of solar systems.

Solar pumps WILO are available with various connection thread dimensions, delivery heights, and maximum flow rates, making them suitable for a wide range of applications. They are powered by a modern energy-saving EC motor with low consumption, high resistance to blockage, and integrated electronic performance regulation.

Solar Circulation Pump Grundfos Solar

In our offer, you will also find pumps for solar systems from the leading global manufacturer Grundfos. The Solar product line is specifically designed for solar thermal systems. Thanks to a wide range of models, Grundfos Solar pumps are suitable for all types of photothermal systems.  

Electronic circulation pumps Grundfos Solar allow remote control of pump speed, enabling you to optimize solar energy collection and save costs. Their advantages also include compact design and easy installation. Safety of operation and long life are ensured by a cataphoretic coating of the cast iron body, double-insulated cabling, and motor protection against water condensation.

Solar Energy – The Future of Heating and Water Heating

Solar energy is now commonly used for electricity production. Direct water heating using photothermal systems is several times more efficient than water heating using electricity from photovoltaic panels.

The initial investment for a typical family house is around 150,000 CZK, with state subsidies available for photothermal systems to cover a significant portion of the initial costs (approximately 50,000 CZK). Annual savings on heating and water heating with this system reach 50% (average over the year). The return on investment is thus 3-5 years. Photothermal systems save energy, your wallet, and, last but not least, the environment.