Installation location and precautions for household photovoltaic inverters

An inverter is a power regulation device composed of semiconductor devices, which is mainly used to convert DC power into AC power. It is generally composed of a boost circuit and an inverter bridge circuit. The boost circuit boosts the DC voltage of the solar cell to the DC voltage required for the inverter output control; the inverter bridge circuit converts the boosted DC voltage into an AC voltage of a common frequency. The inverter is mainly composed of switching elements such as transistors, and the DC input is converted into an AC output by regularly allowing the switching elements to repeatedly switch on and off. Of course, the inverter output waveform generated by simply opening and closing the circuit is not practical. Generally, high-frequency pulse width modulation (SPWM) is required to narrow the voltage width near the two ends of the sine wave and widen the voltage width in the center of the sine wave, and always allow the switching element to move in one direction at a certain frequency within a half cycle, thus forming a pulse wave train (quasi-sine wave). Then let the pulse wave pass through a simple filter to form a sine wave.

Components composition:

1. Current sensor

Photovoltaic inverters generally use Hall current sensors for current sampling. The current sensors used vary from low power to high power. Some examples are listed below:

100KW: The detection current is about 300A, and JCE308-TS7 current sensor is generally used

250KW: The detection current is about 500A, and the JCE508-TS6 current sensor is generally used.

500KW: The detection current is about 1000A, and the JCE1005-FS current sensor is generally used.

1MW: The detection current is about 2000A, and the JCE2005-FS current sensor is generally used

The current sensor is required to have high accuracy, fast response time, and be resistant to low and high temperature environments.

2. Current transformer

Generally, BRS series current transformers are used, ranging from several hundred to several thousand A, and the output signal is generally 0-5A as the standard

Where is the best place to install a home photovoltaic inverter?

1. Installation on photovoltaic bracket and precautions

The common installation scheme for ground distributed projects is to install it near a certain string of components, using a fixed bracket or a clamp to directly fix the equipment on the column. This scheme requires attention to the strength of the bracket and the column and the height of the photovoltaic inverter from the ground to prevent it from being placed too low and flooded by rainwater during heavy rain.

2. Installation on the roof and precautions

This type of installation is mainly used in large industrial and commercial factories. Since the roof is empty and there is no ceiling or parapet, there is no place to hang the photovoltaic inverter. In order to reduce the cost of cables, the photovoltaic inverter generally requires a self-made mounting bracket. The photovoltaic inverter is hung on the self-made bracket. The bracket needs to consider the load-bearing and fixing form of the inverter as well as the typhoon resistance in coastal areas.

As we all know, the life of electronic devices is halved for every 10°C increase in ambient temperature. For this type of installation, if the inverter is exposed to the sun for a long time, the internal temperature of the inverter will increase greatly, seriously affecting the life of the key components of the inverter. The inverter will operate at a reduced rating to protect the internal components, and even the over-high temperature may cause a temperature failure of the inverter. It is recommended to add a sunshade to the photovoltaic inverter to avoid exposure to the sun.

When photovoltaic inverters are installed vertically on a flat roof, shadows will be generated. Therefore, when installing the equipment, the components should be installed outside the shadow range of the inverter as much as possible to avoid shadows on the components.

3. Installation on the wall and precautions

A common form of rooftop power station installation for household distributed projects. In this form of installation, the photovoltaic inverter should be installed on the south wall as much as possible, and the panel of the photovoltaic inverter should face north to avoid sunlight. The specific installation requirements are as follows:

(1) The machine should be installed at a suitable height from the ground to facilitate observation and reading of the LED display.

(2) When installed outdoors, a rain and sun awning should be installed on the photovoltaic inverter to avoid direct sunlight and rain. The inverter should not be directly exposed to the sun or other heat sources.

(3) Sufficient space should be left for installing and moving the inverter. For inverters with air inlet and outlet from top to bottom, at least 50cm of space should be left around them. For inverters with air inlet and outlet from left to right, air is taken in from the sides, and at least 100cm of space should be left on both sides.

(4) It must have sufficient load-bearing capacity, which should be at least 1.5 times the weight of the inverter.

(5) The heat dissipation air duct of the photovoltaic inverter is downward-intake and upward-outlet. The inverter should be installed vertically. Horizontal installation or upside-down installation is strictly prohibited.

(6) The photovoltaic inverter must be placed in a space with good air circulation. There are two types of inverters: forced air cooling and natural heat dissipation. The inverter itself is a heat source, and all heat must be dissipated in time. It cannot be placed in a closed space, otherwise the temperature will rise higher and higher.

How to choose the installation location of the photovoltaic inverter

1. Do not install the inverter in direct sunlight. Otherwise, it may cause excessive internal temperature of the inverter, and the inverter will operate at a reduced rating to protect internal components. Even excessive temperature may cause inverter temperature failure.

2. The installation site should be strong enough to support the weight of the inverter for a long time.

3. The ambient temperature of the selected installation site is -25°C~50°C and the installation environment is clean.

4. The humidity of the selected installation site shall not exceed 95% and there shall be no condensation.

5. There should be enough clearance in front of the inverter to facilitate data observation and maintenance.

6. Make sure the installation location will not shake.

Photovoltaic inverter installation precautions

1. Before installation, you should first check whether the inverter is damaged during transportation.

2. When selecting a site for installing a photovoltaic inverter, ensure that there is no interference from any other power electronic equipment in the surrounding area.

3. Before making electrical connections, be sure to cover the photovoltaic panels with opaque materials or disconnect the DC circuit breaker. The photovoltaic array will generate dangerous voltage if exposed to sunlight.

4. All installation operations must be completed by professional technicians only.

5. The cables used in the photovoltaic system power generation system must be firmly connected, well insulated and of appropriate specifications.

6. All electrical installations must meet local and national electrical standards.

7. The inverter can be connected to the grid only after obtaining permission from the local power department and all electrical connections have been completed by professional technicians.

8. Before performing any maintenance work, first disconnect the electrical connection between the inverter and the grid, and then disconnect the DC side electrical connection.

9. Wait for at least 5 minutes until the internal components are fully discharged before performing maintenance work.

10. Any fault that affects the safety performance of the inverter must be eliminated immediately before the inverter can be turned on again.

11. Avoid unnecessary circuit board contact.

12. Comply with electrostatic protection regulations and wear an anti-static wrist strap.

13. Pay attention to and comply with the warning signs on the product.

14. Before operation, conduct a preliminary visual inspection of the equipment to see if it is damaged or in other dangerous conditions.

15. Pay attention to the hot surface of the inverter. For example, the heat sink of the power semiconductor will remain at a high temperature for a period of time after the inverter is powered off.