Among the technical parameters of the inverters, there is a maximum allowable access power. It is necessary to consider illumination conditions, installation site, components and inverters.1.
Among the technical parameters of the inverters, there is a maximum allowable access power. Most manufacturers are labeled as 1.1 to 1.2 times the rated power, but some manufacturers are labeled as 1.4 times the rated power or even 1.7 times the rated power in order to show their overmatching ability. Users design the system according to this technical parameter, which will cause power loss to users. Inverters only account for about 5% of the cost of photovoltaic systems. It is not only inexpensive but also brings other problems to reduce the investment of Inverters by overmatching components. It is necessary to consider illumination conditions, installation site, components and inverters.
1. Illumination Conditions
1.1 Regional irradiance
The larger the solar altitude angle is, the shorter the path through the atmosphere is. The smaller the weakening effect of the atmosphere on solar radiation, the stronger the solar radiation reaching the ground. In areas with good solar energy resources, due to less clouds, good air quality and high atmospheric transparency, the radiation from the sun to the surface of the module is much higher than in areas with poor solar resources.
1.2 Installation Elevation
The higher the altitude, the thinner the air is, the smaller the weakening effect of the atmosphere on solar radiation, the stronger the solar radiation reaching the ground. The thinner the air is, the worse the heat dissipation of the inverters will be. When the altitude exceeds a certain height, the inverters will operate at a reduced rate. In high seas, the inverters generally need to consider fewer components.
2.Installation Site Factors
2.1 DC side system efficiency
In photovoltaic system, energy from solar radiation to photovoltaic modules, through DC cables, shunt boxes, DC distribution to the inverters, all of which have losses. The loss of DC side varies greatly with different installation methods. For centralized ground power station, the efficiency of DC side system is usually about 90% due to the long DC cable in front, the shunt box, DC distribution cabinet, anti-reverse diode, DC switch and other equipment and devices. In the distributed photovoltaic system, because the components are connected to the inverters directly, there are no other accessories. If the inverters are installed nearby, the DC cable can be very short, and the efficiency of the DC side system can reach 98%.
2.2 Inverter Heat Dissipation Conditions
Inverter should be installed in a well ventilated place to avoid direct sunlight, which is conducive to heat dissipation. If the site is limited, the inverters have to be installed in the closed area which is not conducive to heat dissipation, the reduction of the inverters should be considered, and fewer components should be allocated.
2.3 Voltage Variation of Power Grid
The quota output power of the inverters is the maximum power at rated output voltage, which is not invariable. If the grid voltage drops during the peak period of power consumption, the inverters will not reach the rated power.
3.1 Power Positive Tolerance
In order to satisfy the photovoltaic module attenuation of less than 20% in 25 years, many component factories have a 0-5% tolerance to the newly manufactured components, such as 265W components, the actual power of the newly manufactured components may be 275W.
3.2 Negative Temperature Coefficient
The power temperature system of the module is about - 0.41%/. When the temperature of the module decreases, the power of the module will increase.
3.3 Double-sided Component
The two-sided module can receive not only the radiation power of the front sunlight, but also the reflected radiation power of the back sunlight. Different objects have different reflectivity of sunlight in different spectral bands. Snow, wetland, wheat and desert have different reflectivity in the same wave band, and the same thing has different reflectivity in different wave bands.
4. Inverter factors
4.1 Inverter Efficiency
The efficiency of the inverters is not constant. The power switching device losses and magnetic losses are relatively low at low power. When the power is 40% to 60%, the efficiency is the highest. When the power is over 60%, the efficiency decreases gradually. Therefore, the total power of photovoltaic power should be controlled between 40% and 60% of the inverters'power to achieve the best efficiency.
4.2 Life of Inverter
Photovoltaic inverters are electronic products, and their reliability is closely related to the operating temperature of the inverters. When the temperature of capacitors, fans, relays and other components is increased by 10 C, the failure rate can be increased by more than 50%. And the operating temperature is related to power. According to statistics, the inverters work at 80-100% power over a long period of time, 40-60% power over a period of time, and their life is about 20% lower.
4.3. The Optimum Voltage Range of Inverter
The working voltage is the most efficient when the rated working voltage of the inverter is used.
Output Power and Overload Capability of 4.4 Inverter
Different brands and the same power section of the inverter, the output power is also different, so when buying inverters, we should look at the manufacturer.
To sum up all kinds of factors, the ratio of inverters and components is really not a simple matter. We should consider all kinds of factors comprehensively. For example, components are like precious goods, while inverters are a horse. We prefer a carriage with a big horse to a carriage with a small horse. Xindun is an expert in inverters and photovoltaic modules . If you have any questions, please come to consult us.