(1) Inspection of appearance and documentation
① Visually inspect the appearance of the equipment and whether the main components are damaged; whether the components are loose or missing; whether the cabinet panel is flat, whether the surface coating is firm, the paint surface should be well-proportioned, without peeling, rust and cracks; whether various switches are easy to operate, flexible and reliable.
②Visually inspect whether the label content is accurate and standard; whether various function switches and instructions, displayed icons and text descriptions are clear and correct; whether the access points and positive and negative polarities of solar cells, storage batteries and loads are marked.
③Check whether the equipment manual, inspection certificate and other documents are complete; whether the attached spare fuses and other accessories meet the specifications and quantity of the packing list.
(2) Fully disconnected and restored control voltage starting point detection
①Switch type controller: a controller with full disconnection and connection recovery functions. For this type of on/off controller, when it is used to control a battery with a design standard value of 12V, the reference value of the starting control point voltage for full disconnection and recovery of connection is as follows.
Start-up lead-acid battery is fully disconnected: 15.0~15.2V; recovery: 13.7V.
Fixed lead-acid battery is fully disconnected: 14.8~15.0V; recovery: 13.5V.
The sealed lead-acid battery is fully disconnected: 14.1~14.5V; recovery: 13.2V.
For a sealed lead-acid battery with a design standard value of 24V, full disconnection: 28.2~29.0V; recovery: 26.4V.
The charging and discharging working voltage starting point detection method of the switching controller is shown in Figure 1. Connect the DC stabilized power supply to the battery input terminal of the controller to simulate the input voltage of the battery. Use a voltmeter to monitor the voltage of the stabilized power supply, adjust the voltage of the stabilized power supply to reach the point of full disconnection, the controller should be able to disconnect the charging circuit, and adjust the stabilized power supply again to lower the voltage to restore the charging point voltage, the controller should be able to reconnect the charging circuit.
②Pulse width modulation controller: The main difference from the switching controller is that the charging and discharging circuit does not have a fixed recovery charging point voltage. When using it to control a battery with a standard value of 12V, the reference value for the starting control point of its full voltage.
Start-up lead-acid battery is fully disconnected: 15.0~15.2V.
The fixed lead-acid battery is fully disconnected: 14.8~15.0V.
The sealed lead-acid battery is fully disconnected: 14.1~14.5V.
The detection method of the starting point of the pulse-width modulation controller is shown in Figure 2. Connect the DC stabilized power supply to the input terminal of the solar panel of the controller, simulate the solar battery to charge the battery, and monitor the voltage of the battery with a voltmeter. When the battery voltage is full, the charging current should be close to zero; when the battery voltage drops from the full point to the point, the charging current should gradually increase.
(3) Under-voltage disconnection and recovery control voltage starting point detection
When the battery voltage drops to 1.80±0.5V per unit at the overdischarge point (2V battery is 1 unit; 12V battery is 6 units; 24V battery is 12 units), the controller should be able to automatically cut off the load. When the battery voltage rises to the charge recovery point of 2.2~2.25V per unit, the controller should be able to automatically or manually restore the power supply to the load.
Figure 3 shows the test method for the starting point of undervoltage disconnection and restoration of the control voltage. Connect the DC stabilized power supply to the battery input terminal to simulate the battery voltage. Connect the matched DC energy-saving lamp or LED lamp to the load end, and then adjust the voltage of the DC stabilized power supply to the undervoltage disconnection voltage starting point, and the controller should automatically disconnect the load. Adjust the voltage to the recovery point and the controller should be able to connect to the load again. If it is a controller with undervoltage lockout function, the controller should be able to connect to the load after resetting.
Generally, the nominal value of a battery with a nominal value of 12V, the reference value of the undervoltage disconnection and recovery voltage starting point: the undervoltage disconnection voltage starting point is 11.1~11.4V; the automatic or manual recovery voltage starting point is 13.2~13.5V.
Read more: Contents and methods of inspection and testing of photovoltaic controllers Part Two