String photovoltaic (PV) inverters directly convert the direct current (DC) generated by PV modules into alternating current (AC), which is then boosted and connected to the grid. Therefore, the power output of these inverters is relatively small. PV power plants typically use string PV inverters with a power output of 50kW or less. So, what are the advantages and disadvantages of string PV inverters?
Advantages of string photovoltaic inverters:
1. Unaffected by differences between modules in the same string and by shading, it also reduces the mismatch between the optimal operating point of the photovoltaic module and the inverter, maximizing power generation;
2. MPPT has a wide voltage range, allowing for more flexible module configuration; it also provides longer power generation time in areas with cloudy, rainy, or foggy conditions.
3. Small size, small footprint, no need for a dedicated server room, and flexible installation;
4. Low self-power consumption and minimal impact from malfunctions.
Disadvantages of string photovoltaic inverters:
1. Power devices have small electrical clearances, making them unsuitable for high-altitude areas; the large number of components integrated together results in slightly lower stability.
2. Outdoor installations are susceptible to aging of the casing and heat sink due to wind and sun exposure;
3. A larger number of inverters increases the overall failure rate and makes system monitoring more difficult;
4. The design without an isolation transformer has slightly lower electrical safety and is not suitable for thin-film module negative grounding systems.
