Solar Inverter

An inverter is an electronic device that converts direct current (DC) into alternating current (AC). For example, it can convert DC power from solar panels or batteries into 220V/380V AC required by household appliances or the grid.

Based on output waveform, they are classified as pure sine wave, square wave, and modified sine wave inverters. Pure sine wave inverters provide the highest quality output and can run any load, but are more expensive. Square wave inverters have poor output quality and limited load capacity. Modified sine wave inverters offer a balance between performance and cost and are the most common in the market.

These are common types in PV systems. String inverters have smaller power ratings (typically 1–110 kW) and are suitable for residential rooftops and small to medium commercial installations. They feature multiple MPPT (Maximum Power Point Tracking) channels, which handle partial shading and different panel orientations better. Central inverters have large power ratings (above 500 kW) and are mainly used in large utility‑scale ground‑mounted solar plants.

Besides DC‑to‑AC conversion, inverters also provide Maximum Power Point Tracking (MPPT) to boost energy yield, anti‑islanding protection for grid safety, power quality optimization, and data acquisition and remote monitoring capabilities.

MPPT (Maximum Power Point Tracking) is a technology that allows the inverter to continuously find the optimal operating point of the PV array. By dynamically adjusting voltage and current based on changes in irradiance and temperature, it ensures the panels always operate at their maximum power point, which can increase overall system energy yield by 10–30%.

Selection depends primarily on the application scenario: grid‑tied, off‑grid, or hybrid? What is the load profile – steady or with high inrush currents (e.g., motors)? Also consider the DC/AC ratio (total PV power vs. inverter rated power), conversion efficiency (choose a product with a maximum efficiency of no less than 99% if possible), and installation conditions like structural load and ventilation.

Do not just look at the “peak efficiency” (e.g., ≥99%) on the datasheet. Pay more attention to the efficiency in the actual operating load range (e.g., 30‑60% load) – often called “weighted efficiency” or “European efficiency”. If the inverter has excellent peak efficiency but poor performance at low loads, your actual energy harvest may be lower than expected.

Yes, very important. The IP rating indicates resistance to dust and water. For example, an IP66‑rated inverter offers good protection against dust and powerful water jets, making it suitable for coastal humid environments or dusty outdoor installations.

Ventilation and heat dissipation: Avoid direct sunlight, ensure good airflow around the unit, and consider installing a sunshade.

Avoid high temperature and humidity: Heat reduces efficiency and shortens lifespan.

Correct wiring: Ensure DC polarity is correct and AC connections are tight.

Proper grounding: Reliable grounding is essential for lightning protection and personal safety.

Ensure the installation location is well‑ventilated and shaded from direct sunlight. A sunshade canopy can help. Regularly clean dust from the cooling fan and air intake grilles to prevent clogging.

It can, but choosing an inverter with a high IP rating (e.g., IP66) provides good resistance to moisture and salt‑spray corrosion, ensuring long‑term reliable operation.

Yes. It is recommended to periodically check:

Cooling system (fans, air intakes for blockages).

Electrical connections (loose or damaged cables).

External condition (any abnormalities, corrosion).

Operational data (via monitoring platform – check if generation is normal).

Resistive loads: Current and voltage are in phase, e.g., incandescent lamps, electric heaters.

Inductive loads: Current lags voltage, e.g., motors, compressors, relays. These have high starting currents (3‑7 times rated current), placing higher demands on the inverter.

Capacitive loads: Current leads voltage, e.g., power factor correction capacitors.

Usually, there is no DC input. Possible reasons: PV voltage is lower than the inverter’s startup voltage, PV input polarity is reversed, the DC switch is not closed, or the PV connectors are loose.

This indicates the inverter does not detect the utility grid. Check: whether the AC breaker is closed, whether the AC output terminals are properly connected, and whether the external circuit breaker (e.g., MCB) has tripped.

This typically means too many PV modules are connected in series, causing the voltage to exceed the inverter’s maximum input limit. Recalculate and reduce the number of modules per string to keep the string voltage within the inverter’s allowable range.

This means the insulation resistance between the PV system and ground is below the safe threshold (usually 2 MΩ or 50 kΩ). Possible causes include damaged cables, water ingress in connectors, or moisture causing a DC ground fault. Inspect all panels, junction boxes, and cables for insulation issues.

This indicates the inverter has detected excessive leakage and has shut down for safety. Try restarting the inverter after disconnecting the PV input. If the problem persists, check the AC grounding for abnormal connections with the live wire, or contact the manufacturer.

It is often due to high grid impedance – when the PV system feeds power into the grid, the voltage at the inverter side rises too much. Solutions include: using a larger AC cable (to reduce resistance) or installing the inverter closer to the point of common coupling (to shorten the cable run).

Possible causes: poor heat dissipation (fan failure, blocked air intake), ambient temperature exceeds the rated limit, improper installation (direct sunlight, enclosed space), or inverter overload.