Being the core component of solar power generation systems, photovoltaic inverters can be approximately classified into three types based on their power range and application scenarios: central inverters, string inverters, and micro-inverters. Each type has its own characteristics and is utilized for different scales of projects.
- Power Station Type Photovoltaic Inverters: They can be used in large-scale applications such as large commercial rooftops, industrial factories, and ground-mounted photovoltaic power plants with a wide range of power from 30KW to 1000KW and beyond. They mainly employ a three-phase bridge circuit topology and are divided into two categories: transformerless and transformer-based.
- String-type photovoltaic inverters: Applicable for domestic and small commercial rooftops, with a power output of 1KW to 30KW. Single-phase units typically feature a boost circuit and single-phase transformerless topology; while three-phase units integrate a boost circuit with three-phase three-level transformerless topology to serve multiple installation requirements.
- Micro-inverters: Having a relatively narrow power range of 200W to 500W, they are specifically targeted for use on facades, window sills, or small rooftops. These inverters can be used with individual modules to track maximum output power individually, thereby eliminating shading problems and increasing the overall efficiency and reliability of the system.
- High Conversion Efficiency: This is one of the most critical parameters for evaluating the performance of photovoltaic inverters. The top companies can provide conversion efficiency of over 98%, and for high-power devices, it can be up to 98.7%, and MPPT efficiency can even reach 99.9%.
- Long life and high reliability: As the likely life of a photovoltaic power generation system is around 20 years, photovoltaic inverter design must also permit stable operation for so many years. As any failure would result in system downtime and economic loss, high reliability is of prime importance.
- Wide DC voltage input range: In practical application, multiple solar cell modules are connected in series to generate a fairly high DC voltage, which is supplied to the inverter through various combinations. For compatibility with various configuration schemes, photovoltaic inverters must supply a wide range of DC voltage inputs and ensure that the output current won't cause a negative impact on the power grid according to grid connection demands.
In short, the selection of photovoltaic inverters must not only be based on their matching power range and specific application condition, but should also be targeted on other topics such as conversion efficiency, lifetime, reliability, and adaptability to different DC voltage inputs. Not only does it enhance the overall efficiency of the solar power generation system, but also ensures long-term stable power supply.
