How to choose inverters for rural users to install on their roofs?

Choice is a headache for many people, because when faced with all kinds of choices and additional conditions, they suddenly find that they don't know how to choose.

Not long ago, I received a message from a friend in the countryside that he wanted to build a 5kW photovoltaic power generation system on his roof, but he fell into "choice obsessive-compulsive disorder" when choosing an inverter!

He first compared the prices on Taobao, the price difference of the same brand was several hundred, and he did not find an official flagship store; then he consulted in the circle of friends on WeChat, and several agents said that they were directly purchased by a certain manufacturer and belonged to a certain place. The chief representative, but there are several general representatives in one place, who should be chosen? In desperation, I contacted several manufacturers, and each of them said that they were better than the other, and listed a lot of advantages, but which one is better? Finally, I found the largest inverter company, but when the other party heard that only one 5kW was needed, they simply said that you should contact an agent in a certain area!

After a lot of tossing, this friend felt uncomfortable—why is it so difficult for us rural people to choose an inverter?

In fact, there are still tricks to be found for the selection of inverters in photovoltaic systems. It can be considered from these aspects: cost, efficiency and operating characteristics.

1. Cost often affects people's choices

For rural users, the construction of photovoltaic systems is not to follow the trend, but to consider new ideas. Most of them are considered from the perspective of financial management and investment. The cost of the system often affects people's choice. This also provides business opportunities for individual merchants to push cheap inverters into the market in order to occupy the market. In fact, it's okay to be cheap, as long as the cheapness is not based on low quality. But in reality, cheap is often equated with low quality.

The photovoltaic inverters for household systems are all string inverters, which are small in size and light in weight, and are very convenient in handling and installation. They do not require professional equipment and tools, let alone power distribution rooms. They are all installed next to the photovoltaic modules, and there is no need to lay cables in a large area, and the cost of supporting installation is relatively low.

Its cost is not external, so where? Certainly inside it, the inverter is composed of many components, such as IGBT, fuse, capacitor, sensor, relay, diode, microprocessor, segment, resistor, etc. Don’t underestimate the difference between these components and components of different brands Still big. In addition, there is a big gap in the panel processing method of the inverter and the size of the display screen.

2. In the era of photovoltaic power generation where efficiency is king, inverter efficiency should be viewed in this way!

When writing this article, I also consulted the mainstream inverter manufacturers in the industry. Judging from the promotion in the brochures, the maximum efficiency of each can almost reach 98%, or even higher. The high efficiency of inverters is the basic guarantee for photovoltaic power generation and user income. The differences in the efficiency of different brands of inverters are mainly due to system optimization and line loss. The string inverter commonly used in the user system, each battery string is input into an inverter, and the inverter performs MPPT on the input battery string separately to ensure that each string can generate the maximum power, Even if a certain string is disconnected due to insufficient solar radiation or due to a fault, other strings will continue to generate electricity normally without being affected.

In practice, the only indicator to consider the efficiency of inverters is the power generation. In order to compare two inverters of different brands, some EPC companies often use the same board with an inverter of the same power, but this comparison It is a method, but it is not absolutely accurate. Here we only say that the power generation displayed on the inverter screen can also be manipulated manually, and the efficiency can also be controlled by software. The most accurate one is based on the meter. This is also why some users wonder why the numbers on the inverter screen are different from the numbers displayed on the meter. Of course, such situations are not very common, but when you encounter them, don't make a fuss. Therefore, when choosing a comparison, it is necessary to find a suitable efficiency comparison method.

Third, mastering the operating characteristics of the inverter will also improve its life and power generation.

We mentioned above that the inverter is composed of so many components, and the working performance of these components determines the performance of the inverter. Inverters in household systems generally have an IP65 protection level, but it does not mean that they are "invulnerable" and "non-toxic and non-invasive".

The operation process of the inverter is a process of exothermic heat. While continuously generating electricity, a large amount of heat is also generated. This requires sufficient convection space around the inverter to dissipate the surrounding heat. Household systems are usually based on natural heat dissipation without fans, and medium and large inverters are often equipped with cooling fans.

Although the inverter has an IP65 protection level, if you expose it to harsh environments for a long time, it will also affect its service life and affect its power generation capacity. If you want the inverter to run stably for 10 or 20 years, its "care" is essential. Although the inverter room will not be configured on the household system, try not to expose it to nature , usually a sunshade will be installed on the top.

Fourth, complete certification can be used as a selection standard.

Regardless of whether the inverter is exported abroad or sold domestically, the country has strict standards for it. The most authoritative domestically is the CQC certification. For projects with special requirements, it must meet the leader certification. You can use this as a reference when choosing .

In addition, the National Quality Inspection Center conducts sampling inspections of different batches of inverter products from domestic inverter manufacturers every year, and will publish the results. If even the national quality inspection department fails to pass the random inspection, you dare to say that the inverter is reliable. of it? It can also be used as a reference when choosing.

Here we will talk about these first. Generally speaking, photovoltaic inverters should be selected according to the actual installation conditions of users, which can not only save engineering costs, simplify installation conditions, shorten the installation cycle, but also effectively improve system power generation. Efficiency can be summarized as the principles of high efficiency, reliability, and low cost. These three are closely integrated. If a problem occurs in a certain item, there will be a "short leg" phenomenon for the entire system. It is even more important to understand that "you get what you pay for." Goods" market unspoken rules.