Efficiency of Solar Inverters

Engr. Dr. Muhammad Nawaz Iqbal

A solar inverter, also known as a photovoltaic (PV) inverter, is a type of power inverter that transforms the variable direct current (DC) output of a photovoltaic solar panel into utility frequency alternating current (AC), which can then be fed into a local, off-grid electrical network or used for other purposes.

To extract the most power from the PV array, solar inverters use maximum power point tracking (MPPT). The intricate interaction between solar radiation, temperature, and total resistance in solar cells results in the I-V curve, a nonlinear output efficiency. The MPPT system’s goal is to sample the cell output and figure out a resistance (load) to get the most power possible under any given environmental conditions.

Modern solar pumping inverters use the solar array’s DC electricity to generate AC voltage, which drives submersible pumps without the use of batteries or other energy storage systems. Solar pumping inverters use MPPT (maximum power point tracking) to adjust output frequency, which in turn regulates the speed of the pumps to prevent damage to the pump motor. The majority of solar pumping inverters feature numerous ports to accept the DC current generated by PV arrays, one port to accept the output of AC voltage, and a further port to accept the input from a water-level sensor.

An inverter that converts solar electricity and connects to battery storage is known as an intelligent hybrid inverter or smart grid inverter. They are also capable of storing electricity from the grid in batteries for future use, unlike off-grid systems with battery storage or grid-tie inverters.

Intelligent hybrid inverters are frequently employed in solar power applications, particularly for solar photovoltaic installations, that use renewable energy for residential use. Solar panels can only produce electricity throughout the day, with peak production occurring about noon. Generation varies and might not match an electrical load’s consumption. Storage of energy for later use and management of energy storage and consumption with an intelligent hybrid (smart grid) inverter are required to close the gap between what is produced and what is used during the evening, when there is no solar electricity output.

Hybrid inverters can be used for on-grid or off-grid applications, and they can assist in resolving grid outages. For on-grid applications, the inverter must decide when to charge the battery and can dynamically choose between battery, solar, or grid electricity to run the local loads.

The primary function of a grid-interactive inverter, also known as a synchronous inverter or simply a grid-tie inverter (GTI), is to synchronize the power line’s phase, voltage, and frequency with the grid. If the utility grid fails, solar grid-tie inverters are made to swiftly cut off from the grid. Due to this NEC requirement, the grid tie inverter will shut off in the case of a blackout in order to safeguard any line workers deployed to repair the electricity system from being hurt by the energy it generates.

The grid-tie inverters on the market today employ a variety of different technologies. The newer high-frequency transformers, traditional low-frequency transformers, or no transformer at all may be used by the inverters. High-frequency transformers use a computerized multi-step process to convert electricity to high-frequency AC, then back to DC, and finally to the ultimate AC output voltage rather than converting direct current directly to 120 or 240 volts AC.