How to Choose a High Power Inverter?

I. Brief introduction to inverters

An inverter is an electronic device that converts low voltage (12 or 24 or 48 volts) direct current into 220 volts alternating current. This is because we usually rectify 220 volts AC into DC for use, and the inverter does the opposite, hence the name. We are in an era of "mobility", mobile working, mobile communication, mobile leisure and entertainment. In this mobile state, people need not only low voltage DC power supplied by batteries or electric batteries, but also the 220 volt AC power that we need in our everyday environment, and inverters can meet this need.

II. Selection of high power inverter

1、Inverter efficiency

Inverter efficiency is an important parameter to measure the performance of an inverter. The inverter efficiency value is used to characterize the size of its own power loss, usually expressed in %. Inverter inverter efficiency is directly related to the system efficiency, if the inverter inverter efficiency is too low, will seriously lead to a decline in system efficiency. In the solar photovoltaic power generation system, the conversion efficiency of the solar cell array is generally not more than 18%, and the cost of solar cells is high, if you want to improve the conversion efficiency of 2% to 3% is very difficult, but to improve the inverter efficiency of 3% to 5% is completely possible. The efficiency of the inverter is an important criterion for the performance of the inverter, which has an important impact on the PV power generation system to improve the power generation and reduce the cost of power generation.

2、Rated output capacity

The rated output capacity is used to characterise the ability of the inverter to supply power to the negative stage. The higher the rated output capacity value is, the stronger the inverter's ability to carry load. The rated output capacity value is only a reference for purely resistive loads. If the load carried by the inverter is not purely limited, the inverter's load carrying capacity will be less than the rated output capacity value given.

3、Output voltage stability

Output voltage stability refers to the ability of the inverter to stabilise the output voltage. The deviation of the inverter output voltage within the allowable fluctuation range of the input DC voltage is usually given in the inverter (usually called the voltage regulation rate), and the voltage deviation of the inverter output voltage when the load changes from 0% to 100% is usually given in the high performance inverter (usually called the load regulation rate). The nominal voltage is usually the open-circuit output voltage, i.e. the voltage value without any load connected and without current flowing out. In stand-alone solar PV systems, the voltage at the battery terminals fluctuates greatly during charging and discharging, and the voltage of lead-acid batteries can fluctuate by up to about 30% of the nominal voltage, so the inverter must have good output voltage stability to ensure that the system works within a large DC input range.

4、Reliability

Solar photovoltaic power generation system operation, inverter reliability is the shape of the system reliability of one of the main factors. Because photovoltaic power generation systems generally work in relatively remote and difficult places, maintenance is not convenient, the inverter must be bookable. Its bookability requires the inverter to have good protection functions, including over-current protection and short-circuit protection in the inverter. During the normal operation of a PV power generation system, it is highly likely that a situation such as over-current or short-circuit in the power supply system will occur due to load failure, human misoperation and external interference, etc. To improve reliability, the inverter must be required to have relevant protection functions.

5、Starting performance

Start-up performance refers to the inverter's ability to start up with load and its dynamic working performance. The inverter should be able to ensure its normal starting under the rated negative level. Generally, when the resistive load works, the inverter starting performance is good. However, in the case of inductive loads, such as electric motors, refrigerators, air conditioners or high-powered pumps when starting, the power may be several times more than the rated power. Usually when inductive loads are started, the inverter will be subjected to a large surge power. Therefore, the starting performance of the inverter requires that the internal devices of the inverter can withstand multiple full-load starts without causing damage to the power devices when inductive or other loads are started.