How to configure the power of photovoltaic power plant components and inverters?

In the photovoltaic on grid power generation system, the matching of the power of the photovoltaic inverter and the component is not a fixed ratio of 1:1, but needs to be considered according to the overall situation. The photovoltaic system calculates the system capacity according to the capacity of the component, mainly Influencing factors include irradiance, system loss, inverter efficiency, inverter life, inverter voltage range, component installation angle, etc.

1. Component installation tilt angle and azimuth angle
When the plane of the object is completely perpendicular to the light, the received power is the largest. If the object is tilted, the plane of the object and the light are at a certain angle, the received power will be discounted. For the same area, the received power will be much less. The angle of the component is perpendicular to the sun, and the power is maximum.

2. Irradiance in the installation area
The output power of the module is related to the irradiance. In areas with good solar energy resources, due to less clouds on sunny days, good air quality, and high transparency of the atmosphere, the radiation of the sun reaching the surface of the module is much higher than the average of areas with poor resources.

3. Installation altitude
The higher the altitude, the thinner the air, and the smaller the weakening effect of the atmosphere on solar radiation, the stronger the solar radiation reaching the ground. For example, the Tibetan Plateau is the region with the strongest solar radiation in China. Where the air is thinner, the heat dissipation of the inverter will be worse. If the altitude exceeds a certain height, the inverter will be derated.

4. DC side system efficiency
In the photovoltaic system, the energy from the solar radiation to the photovoltaic components, through the DC cable, combiner box, DC power distribution to the inverter, all of which have losses. Different design schemes, such as the use of centralized, string, distributed and other schemes, the DC side losses are very different.

5. Inverter cooling conditions
The inverter should be installed in a place with good ventilation and avoid direct sunlight, which is conducive to heat dissipation. If the inverter has to be installed in a closed place that is not conducive to heat dissipation due to site constraints, it is necessary to consider the derating of the inverter and fewer components.

6. Component factors
Positive power tolerance: In order to meet the photovoltaic module attenuation of no more than 20% in 25 years, many component factories have a positive tolerance of 0-5% for the components that have just been shipped, such as 265W components, the actual power that has just been shipped may be 270W.

Negative temperature coefficient: the power temperature system of the module is about -0.41%/℃, the temperature of the module decreases, and the power of the module will increase. A 250W module, without considering the equipment loss, may have the maximum output power of more than 250W in areas with the best sunlight in my country, such as northern Ningxia, northern Gansu, southern Xinjiang, etc.

Double-sided components: Double-sided components can not only receive the radiant power of the front sunlight, but also the radiant power of the reflected sunlight on the back. Different objects have different reflectances for sunlight in different spectral bands. Snow, wetland, wheat, desert, different features have different reflectances in the same band, and the same features have different reflectances in different bands.

7. Inverter factor
Inverter efficiency: The efficiency of the inverter is not constant. There are power switching device losses and magnetic losses. At low power, the efficiency is relatively low. At 40% to 60% power, the highest efficiency, when it exceeds 60%, The efficiency gradually decreases. Therefore, the total power of the photovoltaic power should be controlled between 40% and 60% of the inverter power to obtain the best efficiency