Ham Radio General Class Practice Test

What is the reason a series diode is connected between a solar panel and a storage battery that is being charged by the panel?

1. The diode serves to regulate the charging voltage to prevent overcharge

2. The diode prevents self discharge of the battery though the panel during times of low or no illumination

3. The diode limits the current flowing from the panel to a safe value

4. The diode greatly increases the efficiency during times of high illumination

The correct answer is: The diode prevents self discharge of the battery though the panel during times of low or no illumination

The diode is connected in series between the solar panel and the storage battery primarily to prevent self-discharge of the battery through the solar panel when there is low or no illumination. When the solar panel is not generating electricity, such as during the night or cloudy days, the voltage from the battery could potentially flow back into the solar panel. This reverse current can drain the battery, leading to a loss of stored energy and potential damage to the solar panel. By incorporating the diode into the circuit, it allows current to flow only in one direction—from the solar panel to the battery—effectively blocking any reverse current that could discharge the battery. This protective measure ensures that the battery retains its charge when sunlight is not available, which is essential for maintaining the longevity and efficiency of both the battery and the solar energy system. The other choices do not accurately describe the primary function of the diode in this scenario. While regulating voltage, limiting current, or increasing efficiency could be important in very specific contexts, they do not address the key reason for the diode's inclusion in the circuit between the solar panel and the battery.