Solar panel-Inverter technical requirements and performance indicators (II)

- Jan 11, 2019-

(8) Rated output efficiency

 

The new output efficiency refers to the ratio of output power to input power under the specified working conditions. The high inverter efficiency of the whole machine is a distinguishing feature of the inverter used in the photovoltaic power generation system from the general-purpose inverter. The efficiency value of the inverter characterizes the magnitude of its own power loss, usually expressed as a percentage. The rated output efficiency varies with the load rate, the load rate is high, and the rated output efficiency is increased. The inverter with a large capacity should also give a full load efficiency value and a low load efficiency value.

 

(9) DC component

 

When the photovoltaic power generation system is connected to the grid, the DC current component fed by the inverter to the grid should not exceed 0.5% of its AC rating. For PV inverters that are directly connected to the grid without transformers, due to inverter efficiency, etc. The factor can be relaxed to 1%.

 

(10) Harmonic and waveform distortion

 

The output of the photovoltaic system should have low current distortion to avoid adverse effects on other equipment connected to the grid. The total harmonic current of the grid-connected reverser should be less than 5% of the rated output of the inverter.

 

(11) Voltage imbalance

 

When the photovoltaic power generation system is connected to the grid (only for three-phase output), the three-phase voltage unbalance at the grid interface shall not exceed the value specified in GB/T15543, the allowable value is 2%, and the short-term shall not exceed 4%.

 

(12) Protection power value

 

During the normal operation of the photovoltaic power generation system, various faults may occur due to load failure, staff misoperation and external interference. The inverter must have reliable and perfect protection functions to ensure stable and efficient output of electrical energy. For grid-connected inverters, it is especially important to protect islands.

 

(13) Startup characteristics

 

The transformer should ensure reliable and stable starting under rated load. The high-performance inverter can be started continuously for multiple times without damaging the power device. The small inverter sometimes adopts soft start or current limiting for self-safety. .

 

(14) Noise

 

Transformers, filter inductors, electromagnetic switches, and fans in power electronics can generate noise. When the inverter is in normal operation, its noise should not exceed 65dB.