Island system for pumps and solar motors

Motive presents Neo-Solar, an inverter for assembly on motor board directly powered by solar panels that, even if it operates in island-mode (without power supply from the net) it needs no voltage stabilizers and batteries between solar panel and inverter. It can be mounted, for instance, on a pump used in places where the electrical power supply is not available but also simply to have hot water while saving energy. The software of Neo-Solar is optimized compared to standard MPPT (Max Point Power Tracker) systems to achieve the best result from a pump.


The diagram shows a characteristic power/speed of a pump according to the typical solar exposure of a photovoltaic panel. To let the pump work correctly, its characteristic curve must ideally operate within the MPPT limit of the photovoltaic field, with an operational margin in terms of available voltage and current. When the power decreases, the available voltage of the panel will not diminish, permitting the motor to reach anyway nominal speeds but with minor and minor power availability. If the system has been prearranged to make the pump function at its highest performances, once the generator has no more the necessary power, equivalent to the nominal power of the pump, it will stop functioning. A conventional MPPT system, unlike a MPST (Max Point Speed Tracker) system, is not useful for this operation, while a speed variation like that accomplished by Neo-Solar thanks to the combination with solarimeter (optional), and therefore of the power absorbed by the system (according to the power available on the photovoltaic field, for instance directly measured by a solarimeter) will give the certainty of using fully the photovoltaic resource for the maximum water transport.

Moreover, even without a solarimeter, the software of Neo-Solar improves the current supply to the motor compared to a MPPT system, and it is then more suitable for the final target consisting in having sufficient energy to maximise the m2/h prevalence in the course of the day. As a matter of fact, the MPPT system has the different target of constantly pursuing a compromise between current and voltage in order to store the extracted power, part of which, at such voltage and current values, if used to power a motor, would be useless for its operation. It is clear that, to make the pump operate correctly, its characteristic curve must operate within that limit, leaving an operational margin in terms of available voltage and current. The MPPT point is not a working area for the motor, and the use of this power extraction system might uselessly limit the supply of current or voltage to the motor.MOTIVE_02_diagramma

The most conventional alternative in the field of solar pumps consists in using DC motors. Compared to these, Neo-Solar:

  • Can operate with a broad range of already installed motors, since they are typically AC asynchronous motors, without needing their replacement. The asynchronous motor is in fact by far the most diffused and the cheapest and can reach notable efficiencies (IE3) especially on medium-big sizes;
  • The installation and the maintenance of the system is renowned and accessible to technicians worldwide;
  • Compared to pumps with DC motors, amperages are lower, cables have a smaller section and have minor tension losses on the cable;
  • It is possible to connect Neo-Solar simultaneously with solar panels and electrical net and/or generator, to compensate an eventual insufficient solar irradiation or at night;
  • higher maximum power, up to 22 kW.




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