Brief discussion on important parameters of photovoltaic inverters

A large number of PV inverters is available on the market – but the devices are classified on the basis of three important characteristics: power, DC-related design, and circuit topology. 1. Power The available power output starts at two kilowatts and extends into the megawatt range.

With the increased use of PV inverters on the transmission network, the industry is moving towards the ability to provide reactive power capability. Some PV inverters have the capability to absorb or inject reactive power, if needed, provided that current and terminal voltage ratings are not exceeded.

In general, the efficiency of a PV inverter is a function of the input power and input voltage, with a typical set of efficiency curves being shown in Fig. 1.4. At medium to high light levels and therefore input power from the array, the inverter has a high efficiency, generally well in excess of 90%.

Both the maximum voltage value and operating voltage range of an inverter are two main parameters that should be taken into account when stringing the inverter and PV array. PV designers should choose the PV array maximum voltage in order not to exceed the maximum input voltage of the inverter.

If a PV off-grid system is required, it is recommended to add a frequency converter between the inverter and the elevator motor. If the photovoltaic off grid system is only used for pumping water, and a water tower can be built, it is recommended to select the photovoltaic pumping inverter, which can save costs.

It is recommended to match that range when selecting the inverter and the PV array parameters. Inverter MPPT is discussed in EME 812 (11.3 DC/DC Conversion). In most applications, the solar inverters are exposed to ambient conditions such as solar radiation, temperature, and humidity.