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Portable Solar Charger Application

Portable Solar Charger Solar energy is an attractive energy source for portable devices. For some time it has been widely used in applications such as calculators and space shuttles. Recently, Portable Solar Charger people are considering the use of solar energy, including mobile phone chargers such as a wider range of consumer electronics applications.

However, the power provided by solar panels is highly dependent on the working environment. This includes factors such as optical density, time and location. Thus, Portable Solar Charger the battery is typically used as an energy storage unit. When the energy from the solar panel, you can charge the battery; when the solar panel to provide the power is insufficient, the battery can power the system. How do we design a lithium example battery charger to get the most power from a solar cell and effectively charge the lithium battery? First, Portable Solar Charger we will discuss the working principle of solar cells and electrical output characteristics; then, we will discuss the battery charging system requirements and matching solar cell characteristics of the system solutions in order to obtain the maximum power from the solar cells.

In general, the solar cell consists of a p-n structure in which the light energy (photon) causes recombination of electrons and holes to generate current. Portable Solar Charger Because the characteristics of the p-n junction are similar to the characteristics of the diode, the circuit is often used to simplify the characteristics of the solar cell.

The current source IPH produces a current proportional to the amount of light falling on the solar cell. In the absence of a load connection, almost all of the current flows through the diode D, and its forward voltage determines the open circuit voltage (VOC) of the solar cell. The change in voltage is strictly dependent on each type of solar cell. However, for most silicon cells, the voltage range between 0.5V and 0.8V is exactly the forward voltage of the p-n junction diode.

The parallel resistance (RP) represents the tiny leakage current present in the actual solar cell, and Rs represents the connection loss. As the load current increases, Portable Solar Charger most of the current generated by the solar cell is diverted to the diode and into the load. For most of the load current value, this only has a very small effect on the output voltage.

The output characteristics of the solar cell, due to the small I-V characteristics of the diode there is a slight change in the series resistance (Rs) on the voltage drop there is a slight change, but the output voltage remains very constant. However, the current through the internal diode at some point is so small that it becomes biased not enough, and as the load current increases, the voltage across it decreases rapidly. Finally, Portable Solar Charger if all of the current flows through the load and does not flow through the diode, the output voltage is zero. This current is referred to as the short-circuit current (ISC) of the solar cell, which, together with VOC, is one of the main parameters defining the performance. Therefore, the solar cell is considered to be "current limited" power supply. When the output current increases, its output voltage decreases until the final reduction is zero, Portable Solar Charger if the load current reaches its short-circuit current.

In most applications, it is desirable to obtain as much power as possible from a solar cell. Since the output power is the product of the output voltage and the current, it is necessary to determine which part of the cell's work area produces the maximum value of the product of the output voltage and current, which is called the maximum power point (MPP). In an extreme case, the output voltage is its maximum value (VOC), Portable Solar Charger but the output current is zero; in other extreme cases, the output current bit is its maximum (ISC), but the output voltage is zero. In both cases, the product of the output voltage and current is zero. Therefore, the MPP must be somewhere between the two extremes.