The term ‘capacity ratio’ is certainly unfamiliar to laypeople. Capacity ratio refers to the ratio of the nominal power of components in a photovoltaic power plant to the rated output power of the inverter.

If designed according to a 1:1 capacity ratio of the photovoltaic system, the output power of the components cannot reach the nominal power, and the capacity of the inverter will be wasted.

Based on the current technology mastered, adopting ultra configuration design can improve the comprehensive utilization rate of photovoltaic systems, reduce the system’s electricity cost, and is also an effective way and means to increase revenue.

The capacitance ratio is related to the nominal power of the component and the rated power of the inverter, and is affected by external factors. The capacitance ratio is mainly affected by three factors, with significant differences in irradiance in different regions.

According to existing experimental data, even within the same region, there are significant differences in internal radiation levels in different places due to different annual irradiance levels;

The various links of photovoltaic module power output will have power losses, including system losses such as DC accessories, cables, and various devices. Due to the existence of system losses, the module is difficult to work at full load, and the actual output power is only about 90% of the rated power of the inverter;

In addition, the investment cost of the power station, the grid electricity price, and the attenuation caused by component performance differences will all have a certain impact on the setting of the capacity ratio.

The calculation principle of capacity ratio generally follows two types. The first type is to compensate for exceeding the limit, and to increase the system capacity ratio based on the principle that the system will not experience power limiting;

The second type is active overmatching, which increases the system capacity ratio based on the principle of minimizing the system LCOE. This is to consider the power limitation of the inverter or the loss of some energy.

However, from the perspective of comprehensive investment and production, the overall electricity cost will reach a low value. By appropriately increasing the capacity ratio of components and inverters, the comprehensive utilization rate of the inverter can be improved, and the economic benefits of the power station will also be improved.

The level of capacity ratio is related to whether the inverter can operate at full load, without causing capacity waste, and better utilizing the economy of the photovoltaic system.

Therefore, designing a reasonable system capacity ratio is particularly important. Given the different conditions in each resource area, there may be differences in temperature, electricity price levels, and other aspects, and the actual capacity ratio depends on the specific situation.