Inverter To Prevent Heat Problems
Photovoltaic Inverter and PV modules should take into account a number of conditions, such as light altitude factors, installation methods, site factors, components and the inverter itself and so on. Then for everyone to analyze in detail.
Solar energy resources can be divided into five categories, of which one, two, three areas of light resource-rich, most of our belong to these categories, it is very suitable for the installation of photovoltaic power generation system. However, different areas of radiation intensity vary widely, in general, the greater the height of the sun, the stronger the solar radiation; the higher the altitude, the stronger the solar radiation. In areas where the intensity of solar radiation is large, the PV inverter has a poor heat dissipation effect, so the inverter should take the derating operation and the component ratio will be lower.
Installation location, installation in different ways, photovoltaic power plant inverter and component ratio will not be the same.
1, DC side system efficiency
Distributed photovoltaic power plant due to the distance between the inverter and the assembly is very short, DC cable is very short, less loss, DC side system efficiency can reach 98%
In contrast, centralized ground power plants are somewhat inferior. As the DC cable is longer, the energy from the solar radiation to the PV module to go through the DC cable, confluence box, DC distribution cabinet and other equipment, DC side system efficiency is generally below 90%.
2, the grid voltage changes
The maximum rated output power of the inverter is not static. If the grid is down, the inverter will not be able to reach the rated output power. Assuming that we use 33 kilowatt inverter, the maximum output current is 48A, rated output voltage 400V, according to the three-phase power calculation formula, the output power of 1.732 * 48 * 400 = 33kW, if the grid voltage down to 360, then the output power will For 1.732 * 48 * 360 = 30kW, which can not reach the rated power, making the power generation efficiency.
3, inverter cooling
The temperature of the inverter also affects the output power of the inverter. If the inverter cooling effect is poor, then the output power will drop. Therefore, the inverter should be installed in areas without direct sunlight and good ventilation conditions. If the installation environment is not good enough, then you should consider the appropriate derating to prevent the inverter heat problems.
Third, the components of their own factors
PV modules generally have a service life of 25 to 30 years, in order to make the components in the normal life after, still maintain more than 80% of the efficiency of the general component factory in the production are 0-5% of the amount of allowance. Also, we generally believe that the standard working conditions of the component is 25 °, while the PV module temperature drops, the component power will rise.
Fourth, the inverter itself factors
1, inverter efficiency and life
If we long-term inverter in the long-term work, the inverter life will be reduced. Research shows that the inverter long-term work in 80% to 100% power life than 40% to 60% reduction of 20%, because long-term work in high power, the system will be a lot of heat, the system operating temperature is too high to affect the service life The
2, the optimum operating voltage range of the inverter
Inverter operating voltage in the rated voltage of the highest efficiency, single-phase 220V inverter, the inverter input rated voltage of 360V, three-phase 380V inverter, the input rated voltage of 650V. Such as 3 kilowatts of photovoltaic inverter, with a power of 260W, the working voltage of 30.5V 12 most appropriate; and 30 kilowatts of inverter, with power 260W components 126, and then each 21 string is the most appropriate.
3, inverter overload capacity
Good Inverter are generally overloaded, while some companies do not have the ability to overload. Overload capacity of the inverter can overload the maximum output power of 1.1 to 1.2 times, can be more than the overload capacity of the inverter with 20% of the components.
PV inverter and components are not free between, and to be a reasonable match, in order to avoid losses. In the installation of photovoltaic power plants, we must take into account a variety of factors, and choose to have excellent qualifications of photovoltaic enterprises to install.