Principles of Repeater Solar Power Supply System

I. Foreword
of sustainable development in China. The latest Repeater Solar Power Supply System developed by Nanjing Shuanghao Mechanical and Electrical Integration Co. Ltd., with its long lifecycle, saves electricity and maintenance costs significantly.
II. Principles of Repeater Solar Power Supply System
The Repeater Solar Power Supply System is composed of 3 modules. The first is the solar power battery module for the conversion of solar energy into power. The second is the control circuit for the control of charging and discharging between solar cells and storage cells, power supply from the storage cell to the load and safety protection of the repeater at work. The third module is the storage cell, where power converted from solar energy is stored (as is shown in the chart).
1. Solar Cell
Solar cell is the device that converts sunshine into voltage. One thing in common is that with the input of specific light, photoelectric effect will be in place to convert photo-energy into power. A solar cell is pressed from two different materials, forming a pn knot respectively. Under the radiation of sunshine with specific wavelength, difference of potential will emerge between zones n and p, which determines the maximum power supply voltage for this battery. If we connect this battery to a circuit, then this cell is able to supply power to the load.
In theory, the load can work if the solar cell is connected to it for the purpose of power supply. While in reality, solar energy is in constant changes. On the one hand, its power supply duration doesn’t match that of the load; while on the other hand, the load needs to work under specific voltage and current yet a solar cell cannot ensure invariable voltage and current. Consequently, the present solar power supply systems in use have to be combined with storage cells.
The combination of repeater with solar cell demonstrates a unique edge. We all know that though solar energy is green and free, solar cells are extremely costly. At present, the voltage supplied by a solar cell is about 0.5v, which means that a whole load of cells have to be linked together before the gas-discharge sources can work, resulting in a high cost. In contrast, a repeater can work under low voltage at 4.5v to 5v, so that much fewer solar cells will be used with reduced system cost.
2. Control Circuit
As the core of the system, a control circuit has the following functions:：
a. Charging and discharging of control system
When charging, the solar cell charges the storage cell, while discharging, the storage cell powers the load. When the voltage and current of the storage cell cannot sustain the load at work, the control circuit will conduct constant voltage and current processing on the output voltage and current of the storage cell.
b. Timed operation
You can automatically set the system operation time, so when the storage cell’s power or the output voltage is low, it will automatically cut off the load and charge the storage cell by the solar cell.
c. Protective function
The control circuit can protect the system by automatically clearing the circuit when problems like short circuit and open circuit of the load, reverse battery connection and overcharging happen.
3. Storage Cell
A solar cell cannot directly supply power to the load. Instead, it stores the electricity in the storage cell which powers the load. However, the voltage of the storage cell cannot be loaded back to the solar cell, like in a one-way street. The simplest solution is adding a diode between the two.
Through the control circuit, the electricity of the storage cell outputs a constant voltage and then supplies power to the repeater. Since the repeater needs a low working voltage and current, so its requirement on storage cell’s output voltage is greatly lowered by only asking for 4.7-5v of voltage. That makes for much fewer solar cells and lower cost.