Several problems with the use of solar energy combination system for lawn lights

- Jun 28, 2019-

(1) Photosensitive sensor. Solar lawn lights require light-controlled switches. Designers often use photoresistors to automatically turn on and off the lights. In fact, the solar cells themselves are an excellent photosensitive sensor, which is used as a photosensitive switch, and its characteristics are better than those of photoresistors. For a solar lawn lamp using only one 1.2V Ni-Cd battery, the solar cell module is composed of four solar cells connected in series, the voltage is low, the voltage under low light is lower, and even the black voltage is less than 0.7V, resulting in The light control switch failed. In this case, the problem can be solved by adding a transistor directly coupled to the amplification.

(2) Control the load according to the battery voltage. Solar lawn lights tend to have high maintenance time for continuous rain, which increases system cost. We reduce the number of LED accesses when the continuous rainy battery voltage is reduced, or reduce the daily illumination time of the solar lawn light, which can reduce system cost.

(3) Solar cell package form. At present, there are two main types of solar cell packaging, lamination and dispensing. The lamination process can guarantee the working life of the solar cell for more than 25 years. Although the epoxy is beautiful at the time, the working life of the solar cell is only 1-2 years. Therefore, the low-power solar lawn lamp below 1W can be used in the form of epoxy dispensing without the requirement of high life. For the solar lawn lamp with the specified service life, it is recommended to use the laminated package.

(4) Blinking and dimming. Gradual dimming is a good way to save energy. On the one hand, it can increase the solar lawn illumination effect. On the other hand, it can control the average output current of the battery by changing the blinking duty cycle, prolong the system working time, or reduce it under the same conditions. The power of solar cells will be greatly reduced.

(5) Switching speed of three-color primary color energy-saving lamps. This problem is very important. It even determines the service life of the solar lawn lamp. The three-color primary color energy-saving lamp has a starting current of 10-20 times when it is started. The system may experience a large drop in voltage under such a large current. The solar lawn light cannot be started or restarted until it is damaged.

(6) Improvement of the efficiency of the booster circuit and its influence on the LED lamp. Low-power solar lawn lights generally have a boost circuit. If an oscillating circuit is used, the inductor is boosted. The inductor uses a standard color code inductor. In the standard color code inductor, an open magnetic circuit is used, and the magnetic flux loss is large, so the circuit efficiency is low. If a closed magnetic circuit is used to make an inductor boost, such as a magnetic ring, the efficiency of the boost circuit will be greatly improved. The characteristics of the LED are close to the Zener diode, the operating voltage changes by 0.1V, and the operating current may vary by about 20mA. In order to be safe, the series current limiting resistor is used under normal circumstances. The great energy loss is obviously not suitable for the solar lawn lamp, and the brightness of the LED varies with the working voltage, and it must be automatically limited, otherwise the LED will be damaged. Generally, the peak current of the LED is 50-100 mA. The reverse high-energy battery is reversed or the battery is unloaded. When the peak voltage of the booster circuit is too high, it is likely to exceed this limit and damage the LED.

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