The A-Z WATER 2.0 unit offers a full-colour graphic LCD touchscreen display, which clearly informs about the operating conditions and parameters of the entire system in the Czech language. Operation is as clear and simple as possible thanks to the use of graphic elements that intuitively present individual functions. In addition to the graphical control and display of the function mode, there is also a precise measurement of the PV parameters, including the value of the total power delivered from the PV panels to the storage tank.

For maximum safety and user comfort, we have newly added the "AntiLegionella" and "FreezeSafe" functions. In the case of the first function, the storage tank is sanitized periodically every 30 days to prevent the multiplication of Legionella and E. coli bacteria. The system also provides a check that the sanitation has been carried out as required. If not, it prompts the customer to take action if necessary (e.g. increase the temperature on the boiler thermostat).

The latter function prevents the temperature of the storage tank from falling below 5 °C to prevent the water from freezing and damaging the storage tank. Both functions are user selectable. Another function, and perhaps the most important one, is the cartridge power adjustment function, where even in case of an unsuitable (higher) PV string voltage, the power is limited to the set value and thus the cartridge overload is prevented! This feature greatly facilitates the selection of panels, extends the life of the cartridge and the unit itself, and prevents potential damage and resulting service actions.

Along with this feature, new "SMART" protections are implemented in the device to minimize potential problems caused by incorrect installation or improper selection of PV panels for trouble-free and stable operation of the entire system controlled by the A-Z WATER 2.0.

The device now has a WiFi interface. After connecting the unit to the home WiFi network, the customer will get automatic system updates including possible addition of new functions, accurate time from the Internet and in the future cloud monitoring and control.

This functionality is also linked to the function of two time windows, which replace the HDO input for time and cost optimization of comfort temperature compliance in automatic mode.

According to the set mode, the device directly feeds the boiler from the solar panel production without unnecessary losses. For optimum efficiency, the power from the panels is processed through the MPPT, thus guaranteeing the optimum operating point and the highest efficiency of power generation.

Since the boiler is essentially a purely ohmic load, the power is processed virtually from the first watt (>50W production) of energy produced from the panels directly to the hot water. Furthermore, the unit is equipped with the MPPS function, where it periodically scans the characteristic of the entire string and in case of a partially shaded panel, finds the optimal point of the entire panel array, thus partially replacing the function of the optimizers on the PV panels.

Due to the versatility of the application, the output voltage is AC (modified sine wave), thus eliminating the need for special boilers for DC power supply. The unit is designed for an input voltage of 75 - 350 V DC with respect to the operating voltage of the boiler heating cartridge! In practice, a combination of 4 to 5 panels with a nominal output of 450 - 550 W per panel with a 230 V boiler is optimal.

A temperature sensor is supplied with the unit, which allows the minimum comfort temperature to be set in full automatic mode and the actual temperature in the tank to be read. The unit requires a permanent connection to the mains but only to operate its own control electronics or, in the case of mains heating, to supply the boiler. The actual consumption of the unit during the time of heating from PV is approximately 0.5 - 3 W (display off without wifi, display on, fan on, wifi communication). Therefore the unit cannot be powered from PV alone, a grid is always required.