### What are the technical parameters of the photovoltaic controller?

At present, there are no national or industry production standards and model identification technical regulations for charge and discharge photovoltaic controllers. There are many types of photovoltaic controllers on the market. Therefore, the selection of model design here refers to the determination of the technical parameters of the product. The following technical parameters are usually given:

(1) System voltage
That is, the rated input voltage of the photovoltaic controller (usually there are 6 nominal voltage levels: 12V, 24V, 48V, 110V, 220v and 500v, and each nominal voltage corresponds to an allowable voltage input range). The rated input voltage of the photovoltaic controller should be consistent with the output voltage of the photovoltaic module (photovoltaic square array), that is, the output voltage of the photovoltaic module (photovoltaic square array) should be within the allowable input voltage range of the photovoltaic controller. If the output voltage exceeds the allowable input voltage range required for control, the photovoltaic controller will stop working.

(2) The maximum charging current of the photovoltaic controller
Usually refers to the maximum output current of photovoltaic modules (photovoltaic square array), according to the power size is divided into 5A, 10A, 15A, 20A, 30A, 40A, 50A, 70A, 75A, 85A, 100A, 150A, 200A, 250A and 300A, etc. Species. When the photovoltaic controller is selected and designed, the maximum charging current of the photovoltaic controller should be greater than the spike current of the load. When the load contains multiple motors, the peak current is
Iif=(KIr)max+Ic
In the formula, (KIr) represents the sum of the starting current of n (n is a natural number) motors starting at the same time, the unit is A; Ic represents the sum of the calculated current of the distribution circuit except the starter motor and the maximum charging current of the energy storage device, The unit is A; K represents the starting current multiple, that is, the ratio of starting current to rated current. Cage motors can reach 6-7, wound rotor motors are 2~2.5, DC motors are 1.5-2, and a single electric arc furnace is 3 , Arc welding transformer and arc welding rectifier are less than or equal to 2.1, resistance welding machine is 1, and flash butt welding machine is 2: Ir means the primary rated current of electric motor, electric arc furnace or electric welding transformer, and the unit is A.

(3) Allowable input channels of the photovoltaic controller
Low-power photovoltaic controllers are generally single-channel input, high-power photovoltaic controllers can input 6 channels, and more can be connected to 12 channels and 18 channels. The allowable input number of the photovoltaic controller should not be less than the number of PV array strings or the number of multiple strings after the DC combiner box is combined (or the number of DC combiner boxes), usually the allowable input of the combiner box There are 10 roads, 14 roads and 18 roads.

(4) Loss of circuit itself
It is also called no-load loss (quiescent current) or maximum self loss. In order to reduce the loss of control and improve the conversion efficiency of photovoltaic power, the loss of the circuit itself of the photovoltaic controller should be as low as possible. The maximum self-loss of the photovoltaic controller shall not exceed 1% or 0.4W of its rated charging current. The loss of the circuit itself is generally 5-20mA. When designing and selecting, the loss of the circuit itself is of course as small as possible.

(5) Battery overcharge protection voltage
The battery overcharge protection voltage is also called full disconnection voltage or overvoltage shutdown voltage. Generally, it can be set to 14,1~14.5V (12V system), 28.2-29V (24V system) according to needs and different battery types. And 56.4~58V (48V system), the typical values ​​are 14.4V, 28.8V and 57.6V respectively. The overcharge protection voltage of the Jing battery and the following overdischarge voltage and float voltage are usually used as design reference. See these for the selected photovoltaic controller Whether the parameters meet the requirements, only the nominal voltage is required when ordering.

(6) Over-discharge protection voltage of battery
The over-discharge protection voltage of the battery is also called under-voltage cut-off voltage or under-voltage cut-off voltage. Generally, it can be set to 10.8-11.4V (12V system), 21.6-22.8V (24V system) according to needs and battery types. And 43.2-45.6V (48V system), the typical values ​​are 11.1V, 22.2V and 44.4 respectively.

(7) Battery charging float voltage
The battery charging float voltage is generally 13.7V (12V system), 27.4V (24V system) and 54.8V (48V system).

(8) Temperature compensation
The photovoltaic controller generally has a temperature compensation function to adapt to different ambient operating temperatures and set a more reasonable charging voltage for the battery. The temperature compensation value is generally -20-40mV/℃

(9) Working environment temperature
The use or working environment temperature range of the photovoltaic controller varies with the manufacturer, generally -20~+50℃