The power generation efficiency of photovoltaic power plants has always been a topic of concern to investors. However, not all power generation efficiency of photovoltaic power plants is the same. In addition to being related to factors such as the amount of solar radiation and the tilt angle of photovoltaic modules, it affects power generation efficiency What are the factors? Let Wenli New Energy take everyone to understand.
1. Solar radiation
When the conversion efficiency of the photovoltaic cell module is constant, the power generation of the photovoltaic system is determined by the solar radiation intensity. In general, the utilization efficiency of photovoltaic systems for solar radiation is only about 10%. Therefore, solar radiation intensity, spectral characteristics, and climate conditions should be considered.
Second, the tilt angle of the photovoltaic cell module
The azimuth of the photovoltaic module is generally selected to the south direction to maximize the power generation per unit capacity of the photovoltaic power plant. As long as it is within ± 20 ° of the true south, it will not have much impact on the power generation. If conditions permit, it should be as far as possible 20 ° southwest.
3. PV Module Efficiency and Quality
Calculation formula: theoretical power generation = annual average total solar radiation * total cell area * photoelectric conversion efficiency. There are two factors: battery area and photoelectric conversion efficiency. The conversion efficiency has a direct impact on the power generation of the power station.
Fourth, component matching loss
All series connection will cause current loss due to component current difference, and all parallel connection will cause voltage loss due to component voltage difference. The loss may reach more than 8%. In order to reduce the loss of matching loss and improve the power generation of the power station, we should pay attention to the following aspects: 1. To reduce the matching loss, try to use components with the same current in series; 2. Keep the attenuation of the components as consistent as possible;
Fifth, temperature (ventilation)
Data show that when the temperature rises by 1 ℃, the large output power of the crystalline silicon photovoltaic module group drops by 0.04%. Therefore, it is necessary to avoid the influence of temperature on power generation and maintain good ventilation conditions.
VI. The loss of dust should not be underestimated
The front panel of the crystalline silicon component is tempered glass, and there will naturally be organic matter and a large amount of dust accumulation in the air for a long time. Blocking light from dust on the surface will reduce the output efficiency of the components and directly affect the power generation. At the same time, it may also cause the "hot spot" effect of the component, resulting in damage to the component.
Seven, shadow, snow cover
In the process of power plant site selection, we must pay attention to the shielding of light. Avoid areas where light can be blocked. According to the circuit principle, when the components are connected in series, the current is determined by the least block, so if there is a shadow, it will affect the power generation of this component. Similarly, winter snow should be removed in time.
Eight, maximum output power tracking (MPPT)
MPPT efficiency is a key factor in determining the power generation of photovoltaic inverters, and its importance far exceeds the efficiency of photovoltaic inverters themselves. MPPT efficiency is equal to hardware efficiency times software efficiency. The hardware efficiency is mainly determined by the accuracy of the current sensor and the accuracy of the sampling circuit; the software efficiency is determined by the sampling frequency. There are many ways to implement MPPT, but no matter which method you use, you must first measure the power change of the component and then respond to the change. The key component is the current sensor. Its accuracy and linearity error will directly determine the hard efficiency, and the sampling frequency of the software is also determined by the accuracy of the hardware.
Nine, reduce line loss
In the photovoltaic system, the cable occupies a small part, but the influence of the cable on the power generation can not be ignored. It is recommended that the line loss of the DC and AC circuits of the system be controlled within 5%. The cables in the system should be well prepared. The insulation performance of the cable, the heat and flame resistance of the cable, the moisture and light resistance of the cable, the type of cable core, and the size and specifications of the cable.
10. Inverter efficiency
The photovoltaic inverter is the main component and important component of the photovoltaic system. In order to ensure the normal operation of the power station, it is particularly important to select the correct configuration of the inverter. In addition to the configuration of the inverter according to the technical indicators of the entire photovoltaic power generation system and the reference to the product sample manual provided by the manufacturer, the following technical indicators are generally considered: 1, rated output power 2, output voltage adjustment performance 3 3. Overall efficiency 4. Start-up performance.