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Influence of photovoltaic inverter MPPT voltage on system power generation
- Jul 17, 2018 -

In photovoltaic systems, the cost of the inverter is less than 5%, but it is one of the decisive factors of power generation efficiency. When the components are completely consistent, different inverters are selected, and the total power generation of the system is 5% to 10%. The difference, the main reason for this difference is caused by the inverter. Maximum Power Point Tracking (MPPT) is a core technology in photovoltaic power generation system. It refers to adjusting the output power of the photovoltaic array according to different ambient temperature and light intensity, so that the photovoltaic array is always Output maximum power. What is the impact of the MPPT voltage range on the PV inverter's power generation?

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The operating voltage range of the inverter is related to the electrical topology of the inverter and the output voltage of the inverter. The string inverter and the distributed inverter are two-stage electrical topology. The MPPT operating voltage range is 250-850V. Between, the centralized inverter is a single-stage structure, the output voltage is 270V, 315V, 400V and other specifications, the input MPPT voltage range is 450-850V, 500-850V, 570-850V, etc., and there is a single-stage structure. The string inverter has only one DC-AC inverter, the output voltage is 400V, and the MPPT input voltage range is 570-850V. From an application point of view, each has its own advantages and disadvantages.

1. From the perspective of the inverter, the higher the output voltage of the inverter, the same power level, the lower the current, the higher the efficiency. The single-stage is simpler than the two-stage structure, high in reliability, low in cost, and inexpensive.

2. From the system point of view, the wider the MPPT voltage range of the inverter, the early start, the late shutdown, and the long power generation time.

3. According to the series principle of voltage source, the system output voltages are added and the current is unchanged. After the PV modules are connected in series, the output current is determined by the minimum number of panels. Due to the components raw materials, processing technology, shadows, dust, etc., the power of one component is reduced, and the power of this series of components is reduced. Less, the number of parallels is as much as possible to reduce the impact of component consistency.