Preliminary study on the design of solar LED garden lights

The solar LED garden light consists of the following components: solar panels, solar controllers, battery packs, LED light sources, poles and fixture housings. Since the load is DC, there is no need to configure the inverter. Assume that the 15W solar LED garden light is illuminated for 10 hours every night, which guarantees continuous rain and rain for 3 days. The power system and capacity design steps are as follows:

1. The power and working time of the load are the prerequisites for selecting the solar module and battery capacity.

The 15W solar LED garden light is illuminated for 10 hours every night, and the average daily load power consumption is 15W×10h=150Wh.

2. Calculation of solar cell component power

Solar panels are the core of solar streetlights and the most valuable part of solar streetlights. Its role is to convert the solar radiation capacity into electrical energy, or send it to the battery for storage.

Solar cell power can be calculated using the following simple formula:

Solar cell module power = power consumption × power consumption time local peak sunshine time × loss factor

The loss factor can be taken as 1.6-2.0, which is 1.6; the local peak sunshine time is 4 hours according to the geographical location of Shandong.

Then: 15W solar LED garden light solar module power = 15W × 10h4h × 1.6 = 60Wp

Therefore, a battery pack having a peak power of 60 Wp is selected.

3. Determine the number of solar cell modules connected and the voltage of the battery according to the system operating voltage level

The general operating system voltage selection principle: household system is 12VDC or 24VDC; communication system is 48VDC; power system is 110VDC; large power station is 220VDC or higher.

Here 15W LED solar light is a small power appliance, the system working voltage can be selected 12VDC, the solar cell module series number is 1, so the solar panel peak voltage is 17V, just to charge the 12V battery.

4. Calculate the required battery capacity

Since the input energy of the solar photovoltaic system is extremely unstable, it is generally necessary to configure the battery system to work. Generally, there are lead-acid batteries, Ni-Cd batteries, and Ni-H batteries. The choice of battery capacity generally follows the following principles: First, the energy of the daytime solar cell module is stored as much as possible while meeting the nighttime illumination, and at the same time, it is also necessary to store the electric energy required for the nighttime illumination of the continuous rainy day. If the battery capacity is too small, it can not meet the needs of night lighting. The battery is too large. On the one hand, the battery is always in a deficient state, which affects the battery life and causes waste. The battery should match the solar battery and the electrical load (street light).

Battery capacity = power consumption of the appliance × power consumption time system voltage × rainy days × system safety factor

The system safety factor is generally chosen to be 1.4-1.8, where 1.4 is selected.

15W solar LED garden light battery capacity = 15W × 10h12V × 3 × 1.4 = 52.5AhAh

So choose a 12V, 50Ah lead-acid battery.

5. Selection of solar controller

Regardless of the size of the solar luminaire, a good performance charge and discharge controller is essential. The following features are required:

(1) High voltage (HVD) disconnection and recovery function: The controller should have the function of input high voltage disconnection and recovery connection.

(2) Undervoltage (LVG) alarm and recovery function: When the battery voltage drops to the undervoltage alarm point, the controller should be able to automatically emit an audible and visual alarm signal.

(3) Low voltage (LVD) disconnect and recovery function: This function prevents overdischarge of the battery. The load is automatically disconnected at a given low pressure point by a relay or electronic switch that connects the load. When the voltage rises to a safe operating range, the load will automatically re-access or require manual re-access.

(4) Protection function: 1 circuit protection to prevent any load short circuit; 2 circuit protection to prevent internal short circuit of charging controller; 3 prevent night battery from reverse discharge protection through solar battery component; 4 prevent load, solar battery component or battery polarity Reverse circuit protection; 5 to prevent breakdown protection due to lightning strikes in the multi-mine area.

(5) Temperature compensation function: When the battery temperature is lower than 25 °C, the battery should require a higher charging voltage in order to complete the charging process. Conversely, batteries above this temperature require a lower charging voltage. Usually, the lead acid battery has a temperature compensation coefficient of -5 mv/oC/CELL.

LED light source, long life, up to 1000000 hours, low operating voltage, no inverter, high light efficiency, domestic 50Lm / w, imported 80Lm / w. As technology advances, the performance of LEDs will further increase, and LEDs as a source of solar streetlights will be a trend.