Some people say that the photovoltaic inverter price is much higher than the module, if not fully use the maximum power, it will cause a waste of resources. Therefore, he thinks that the total power generation of the plant can be increased by adding photovoltaic modules based on the maximum input power of the inverter. But is it really so?

In fact, this is not what the friend said. Photovoltaic inverter and photovoltaic module ratio is actually a scientific proportion. Only reasonable collocation, scientific installation can really give full play to the performance of each part, to achieve the optimal power generation efficiency.Many conditions should be considered between photovoltaic inverter and photovoltaic module, such as light elevation factor, installation method, site factor, module and inverter itself and so on.

First,light elevation factor

Solar energy resource areas can be divided into five classes, the first, second and third types of areas that light resource is rich, most of our country belongs to these classes, so it is very suitable for installation photovoltaic power generation system. However, the radiation intensity varies greatly in different regions. Generally speaking, the greater the solar altitude Angle, the stronger the solar radiation, and the higher the altitude, the stronger the solar radiation. In areas with high solar radiation intensity, the heat dissipation effect of photovoltaic inverter is also poor, so the inverter should be derated to run, and the proportion of components will be lower.

Two, installation factors

The inverter and component ratio of a photovoltaic power station varies with the installation location and method.

1.Dc side system efficiency

Because the distance between the inverter and the module is very short, the DC cable is very short, and the loss is less, the efficiency of the DC side system can reach 98%.Centralised ground-based power stations are less impressive by comparison. Because the DC cable is long, the energy from the solar radiation to the photovoltaic module needs to pass through the DC cable, the confluence box, the DC distribution cabinet and other equipment, and the efficiency of the DC side system is generally below 90%.

2. Power grid voltage changes

The rated maximum output power of the inverter is not constant. If the grid-connected grid drops, then the inverter cannot reach its rated output. Suppose we adopt a 33kW inverter, the maximum output current is 48A and the rated output voltage is 400V. According to the three-phase power calculation formula, the output power is 1.732*48*400=33kW. If the grid voltage drops to 360, the output power will be 1.732*48*360=30kW, which cannot reach the rated power. Making power generation less efficient.

3.inverter heat dissipation

The temperature of the inverter also affects the output power of the inverter. If the inverter heat dissipation effect is poor, then the output power will decrease. Therefore, the inverter should be installed in no direct sunlight, good ventilation conditions. If the installation environment is not good enough, then appropriate derating should be considered to prevent the inverter from heating.

Three. Components themselves 

Photovoltaic modules generally have a service life of 25-30 years. In order to ensure that the module can still maintain more than 80% efficiency after the normal service life, the general module factory has a sufficient limit of 0-5% in production. In addition, we generally believe that the standard operating conditions of the module is 25°, and the photovoltaic module temperature decreases, the module power will increase.

Four, inverter own factors

1.inverter working efficiency and life

If we make the inverter work in high power for a long time, the life of the inverter will be reduced. The research shows that the life of the inverter working at 80%~100% power is reduced by 20% than that at 40%~60% for a long time. Because the system will heat up a lot when working at high power for a long time, the system operating temperature is too high, which affects the service life.

2, the best working voltage range of the inverter

Inverter working voltage at the rated voltage, the highest efficiency, single-phase 220V inverter, inverter input rated voltage 360V, three-phase 380V inverter, input rated voltage 650V. Such as 3 kw photovoltaic inverter, with power of 260W, working voltage of 30.5V 12 blocks is the most suitable; And 30 kW inverter, power distribution for 260W components 126 pieces, and then each way 21 strings is the most appropriate.

3. Overload capacity of inverter

Good inverters generally have overload capacity, and some enterprises do not have overload capacity. The inverter with strong overload capacity can overload the maximum output power 1.1~1.2 times, can be equipped with 20% more components than the inverter without overload capacity.

Photovoltaic inverter and module is not random and for, to be reasonable collocation, in order to avoid losses. When installing photovoltaic power stations, we must consider various factors comprehensively, and choose photovoltaic enterprises with excellent qualifications for installation.