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Factors that affect the power generation of photovoltaic power stations

For photovoltaic power plant investors, each time the power station is more than one degree of electricity income, because the power generation of the power station is directly related to the return on investment cycle, so the investors are most concerned about the power generation of the power station. The power generation of a photovoltaic power station will be affected by many factors, such as: the quality of photovoltaic modules, inverters, cables, component installation orientation, inclination, dust shadow occlusion, photovoltaic modules and inverters matching system scheme, grid quality.

Influence of shadow occlusion on power generation

Among the many factors that affect the power generation of photovoltaic power generation system, shadow occlusion is a more common one, and the common occlusion mainly includes power poles, trees, guardrail, bird droppings, dust and the front and back of components. In the construction process of many power stations, it is often impossible to completely avoid the shadow, and many people will feel that the shadow area is small and will not have a great impact.

In fact, a part of the component or a component is blocked, the whole string of components will be affected, which is the barrel effect of the series circuit, in a string of components, each piece of the current is the same, the maximum current is determined by the smallest piece of the component.

So as long as one component is blocked, it will affect the output power of the whole series. Serious will also cause the component to produce heat spot effect, reduce the power generation efficiency and service life of the component, and even lead to local component burn, bringing certain security risks. Therefore, it is not only necessary to avoid shadow occlusion in the design of the photovoltaic power station, but also to pay attention to late operation and maintenance, and regularly clean the components.

photovoltaic power stations
photovoltaic power stations

Effect of system capacity ratio on power generation

Capacity ratio refers to the ratio of the installed capacity of the photovoltaic system to the rated capacity of the inverter. If the photovoltaic system is designed according to the 1:1 capacity ratio, when the output power of the photovoltaic module does not reach the nominal power, the capacity of the inverter will be wasted. At present, overallocation design is often used to improve the comprehensive utilization rate of photovoltaic system, reduce the system power cost, and improve the power station income.

But this does not mean that you can expand the capacity ratio indefinitely to save inverter investment, because the inverter cost in the entire photovoltaic system accounted for only about 5%, too much overallocation is not only not cost-effective, but also lead to the inverter limit operation, resulting in power generation loss. Therefore, reasonable design of system capacity ratio is conducive to improving the economy of photovoltaic power generation system. In different types of resource areas, due to different solar energy resource conditions, regional temperature and other characteristics are different, need to be calculated according to the specific local conditions.

Influence of improper cable selection on power generation

If the inverter is compared to the brain of a photovoltaic power station, the cable is the nervous system of the photovoltaic system, and the photovoltaic modules, inverters, bus boxes, grid-connected cabinets and other equipment are connected in series into a whole.

Therefore, a reasonable cable selection is crucial to the entire photovoltaic system. Cable design and selection to choose the appropriate wire diameter, especially large photovoltaic power stations, covers a large area, the line is long, if the AC cable wire diameter is too small, it will lead to cable overload, heat, not only affect the power generation, there will be short circuit, fire and other safety hazards.

photovoltaic power stations
photovoltaic power stations

It should also be noted that the same flow carrying cable, aluminum cable is much larger than the cross-sectional area of copper cable, so it is necessary to consider whether the inverter AC end can be accessed. The AC output side of the inverter is designed according to the copper wire benchmark, and it is recommended to use copper core cables. However, the use of aluminum core cables will save a certain investment cost compared to copper core cables, so many installers will use aluminum core cables.

However, it is necessary to use the copper and aluminum wiring transition terminals that meet the standard requirements, because the copper and aluminum joints are prone to electrochemical corrosion, causing poor contact between copper and aluminum, and increasing resistance, affecting the efficiency of the entire photovoltaic system. Long-term operation will cause the joint part of the temperature rise to accelerate corrosion, and even burn.

Cable selection has a direct impact on the power generation of photovoltaic power stations. Choosing the right cable type, specifications, and cables with good load capacity, weather resistance and durability can minimize power loss, improve power generation efficiency, and ensure the normal operation of photovoltaic power stations and maximize power generation.

Influence of power quality on power generation

The power quality of the power grid includes: voltage deviation, current deviation, frequency deviation, voltage fluctuation or flicker, three-phase unbalance, temporary or transient overvoltage, waveform distortion, voltage dip and so on.

  1. The voltage and frequency of the power grid are not constant and will change with the change of load and power flow, and the output voltage of the inverter follows the grid voltage. However, when the voltage and frequency fluctuation of the grid exceed a certain range, the inverter will stop working.
  2. Voltage fluctuations, flickers and harmonics In some mechanical processing plants, there are high-power equipment such as vehicles, welding machines, gantry milling machines, and some electric arc furnace factories, equipment between starting and turning off, power changes are very drastic, while accompanied by a large number of harmonics, harmonics and unbalanced negative sequence components in the power grid will lead to active power fluctuations in the output of photovoltaic systems.
  3. The higher the voltage distortion rate of the grid, the lower the output active power of the PV system. The output current will also be distorted, and the higher the voltage distortion rate of the grid, the larger the output current THD of the photovoltaic system. When the power grid voltage fluctuates sharply, the inverter adjustment ability is limited, which may cause the photovoltaic inverter to restart frequently, and serious cases may cause the power device in the inverter to overvoltage and explode, and the electrolytic capacitor to overcurrent and explode.

From the above points of view, the power generation of photovoltaic power stations not only depends on the power generation performance of photovoltaic power stations themselves, but also closely related to late operation and maintenance, correct operation and maintenance can not only improve the power generation, but also improve the service life of equipment and power stations.

photovoltaic power stations
photovoltaic power stations

Boland Renewable Energy Co.,LTD As an integrated new energy power company, providing you with high quality integrated wind energy , solar energy and energy storage system solutions.Boland is now a subsidiary of CRRC, and is responsible for the overseas expansion of  CRRC's wind power & solar power business. We have a relatively complete internal supply chain, service network and excellent product quality and technology.

Boland Provide power plant EPC,Power plant investment and acquisition.

Please feel free contact us if you need any technical support.Cheers for our cooperation!



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