Types of Solar Inverters
Solar inverters are core components of solar photovoltaic (PV) systems, responsible for converting direct current (DC) generated by solar panels into alternating current (AC) to meet electricity needs in residential, industrial, and other scenarios. Based on different classification criteria, solar inverters can be divided into various types. Here is a detailed introduction to common classifications:
1. Classification by Phase
According to the phase of output AC, solar inverters are divided into single-phase inverters and three-phase inverters, mainly used to match different power grids or load requirements:
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- Single-phase inverters: Output single-phase AC (e.g., 220V), suitable for small-scale PV systems such as residential homes and small commercial buildings. They power single-phase appliances like TVs and refrigerators.
- Three-phase inverters: Output three-phase AC (e.g., 380V), ideal for medium to large PV systems such as industrial plants and large-scale solar farms. They match three-phase loads like three-phase motors and large central air conditioners, offering higher efficiency and stability.
2. Classification by Capacity/Power
Based on rated power, inverters are categorized into micro, small, medium, and large types, corresponding to PV systems of different scales:
- Micro-inverters: Typically with a power range of 200W-1000W, they connect directly to one or a few solar panels (e.g., 1-2 modules). They optimize the power generation efficiency of each panel individually, reducing the impact of shading, dust, etc., on the overall system. Suitable for distributed low-power scenarios (e.g., scattered installation on residential rooftops).
- Small inverters: With power ranging from 1kW to 10kW, they are commonly used in residential or small commercial PV systems. They require a combiner box to balance the current from multiple panels.
- Medium inverters: Power ranges from 10kW to 50kW, suitable for medium-sized commercial buildings, agricultural PV, etc. They can connect multiple strings of panels, balancing efficiency and cost.
- Large inverters: Power exceeds 50kW, even reaching several megawatts (MW). They are mainly used in large ground-mounted solar farms, featuring high reliability and low maintenance costs, usually paired with centralized combiner systems.
3. Classification by Circuit Topology
Based on the circuit design for converting DC to AC, the main types are centralized inverters and string inverters, with significant differences in application scenarios and performance:
| Type | Characteristics | Application Scenarios |
|---|---|---|
| Centralized inverters | Aggregate DC from all solar panels before conversion; high power (hundreds of kW to MW); low cost but vulnerable to issues with individual modules (e.g., shading reduces overall efficiency). | Large ground-mounted solar farms |
| String inverters | Each string of panels (usually 10-20 modules) connects to one inverter; optimizes the efficiency of each string individually; strong anti-shading capability; flexible installation; power mostly 10kW-50kW. | Distributed PV (rooftops, industrial/commercial), mountainous/complex terrain farms |
4. Classification by Energy Storage Capability
With the development of PV + energy storage, inverters are divided into grid-tied inverters and energy storage inverters (bidirectional inverters):
- Grid-tied inverters: Only convert solar DC to AC for grid connection, without energy storage. They are the mainstream equipment in traditional PV systems.
- Energy storage inverters: Feature bidirectional conversion. They can invert PV DC to AC for loads or grid connection, store excess energy from the grid or PV in batteries (DC charging), and invert battery DC to AC for loads during power outages (off-grid mode). Suitable for scenarios of “self-consumption with surplus storage”.
5. Other Special Types
- Off-grid inverters: Not connected to the grid, they are used in off-grid PV systems, paired with batteries. They convert PV DC to AC for local loads (e.g., remote areas, RVs) and require stable voltage and frequency control.
- Micro grid-tied inverters: Combine micro-inverter and grid-tied functions. Each panel connects to one inverter for direct grid connection, acting as a “mini version” of string inverters. They further improve system efficiency and reliability, especially for rooftops with panels facing different directions or prone to shading.
Summary
When choosing a solar inverter, factors such as PV system scale, installation environment (e.g., presence of shading), energy storage needs, and grid type (single-phase/three-phase) should be considered. For example, string or micro-inverters are common for residential rooftops, centralized inverters for large farms, and off-grid inverters with batteries for remote off-grid systems. With technological advancements, inverters with intelligent monitoring and MPPT (Maximum Power Point Tracking) functions have become mainstream, further enhancing PV system efficiency.