Solar street lamp mainly consists of solar photovoltaic cell module, battery, charge and discharge controller, lighting fixture and so on. The bottleneck in the popularization of solar street lamps is not a technical problem, but a cost problem. In order to improve the stability of the system and maximize its performance on the basis of reducing the cost, it is necessary to match the output power, battery capacity and load power of the solar photovoltaic cell reasonably. For this reason, theoretical calculation alone is not enough. Due to the rapid change of sunlight intensity, the charging current and discharge current are constantly changing, so the theoretical calculation will bring a large error. The maximum power output of photovoltaic cells in different seasons and directions can be accurately determined only by automatic tracking and monitoring of charging and discharging current. This ensures that the battery and load are reliable.

The conditioning circuit is used to sample the output current of photovoltaic cells, the discharge current of batteries and the charging and discharging voltage of batteries at a certain frequency, and the collected data is sent to the computer through the USB data acquisition module. Timely display and statistical analysis are carried out on LabVIEW software platform.

The battery output signal is a floating signal. Using differential measurements minimizes the impact on the circuit under test and reduces measurement errors. In the conditioning circuit, the differential amplifier made of the integrated op-amp ICL7650 with high precision and low drift is adopted, and the differential signal above the precise small resistance in series with the charge-discharge circuit is used as the current detection signal. The small signal obtained from the large resistance divider built into the battery is taken as the voltage signal. In order to eliminate interference, two equivalent resistors are connected between the two inputs of the differential amplifier and the signal ground. The output signals of the two differential amplifiers are respectively sent to the two input channels of the USB acquisition module to complete the signal conditioning and acquisition.