Solar Inverters & PCUs

A grid-tie inverter works only with the grid and has no battery; it shuts down when the grid fails. An off-grid inverter or PCU runs from solar and batteries without the grid. A hybrid inverter works with solar, batteries and grid together, supplying backup during outages and optionally exporting surplus. Choose by whether you need battery backup.

A PWM controller connects the array to the battery directly through a switching stage, so the array operates at battery voltage and some power is lost. An MPPT controller converts the array voltage to the battery voltage while tracking the maximum power point, harvesting more energy, particularly with higher-voltage arrays or in cooler weather. MPPT costs more.

Anti-islanding protection forces it to shut down when the grid goes away, so that it does not feed power into a line that utility staff are working on. Without a battery and hybrid inverter, solar will not power the building during an outage. A hybrid inverter or a separate backup arrangement is needed.

Match the inverter's AC rating to the array size, usually in the range of the array kWp, and check that the string voltage stays inside the MPPT window at both cold and hot temperatures. A slightly higher DC array size relative to the inverter AC rating is common. The solar calculator gives a start, and the designer should confirm.

Usually yes. In India, grid-connected rooftop systems need approval and metering arrangements from the DISCOM, often under net metering or similar rules, which differ by state. The inverter must meet the grid code and safety requirements. Check your DISCOM's current procedure before ordering.