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Solar energy as a new energy source has begun to be accepted by people. The development of solar street lights has also received strong support from the government. More and more road installation teams are choosing to install solar street lights. However, different installation environments have different requirements for solar street lights, and their configurations vary accordingly. So what specific parameters are involved in installing solar street lights? In this article, we will introduce you to this topic.
1. System Rated Voltage
This refers to the rated voltage of the battery. The voltage of a single solar cell is generally between 0.4 to 0.7V. Common solar panel configurations are series connections of 36/54/60/72/96 cells, resulting in voltages of approximately 18/27/30/36/48 volts.
2. LED Head Power
This refers to the power of the LED head or the efficiency of the controller driver. It is determined based on the specific installation environment. The higher the lamp pole, the better the illumination effect, which naturally requires a higher head power.
3. Battery Capacity
The size of the battery capacity is also an important point of concern. If the capacity is too small, it cannot meet nighttime lighting needs; if it is too large, the battery will always be in a discharged state, leading to waste and affecting its lifespan.
The capacity ratio of the battery (Ah) to the load capacity (Ah) should be maintained at 3-6 times. If the installation area experiences few consecutive rainy days, a ratio of 3-4 times is sufficient; if there are many consecutive rainy days, the ratio should be at least 5-6 times.
4. Rainy Day Compensation
This is determined based on local climate conditions. During rainy days, the charging efficiency of the solar panel is naturally lower than on sunny days. Therefore, it is essential to ensure that the battery can store enough energy to allow the solar street lights to function normally during rainy days, which also involves the efficiency of the solar panels.
5. Interval Between Consecutive Rainy Days
This refers to the number of sunny days between two consecutive rainy days. It is noteworthy that, in calculating relevant parameters, the average sunlight is used as the basis for charging during sunny days; the actual sunlight during sunny days must exceed the average sunlight.
Moreover, there is also some energy coming into the battery during rainy days, so when using this parameter in calculations, it is not necessary to select the actual interval of consecutive rainy days. It is appropriate to use a ratio of 1:3 or 1:4 between rainy days and the interval between them.
6. Local Solar Radiation Amount
This can be directly searched online. Select the average radiation amount at the best angle, requiring the lowest value of three months’ average. During installation, attention must also be paid to the angle and direction to ensure that the solar street light receives adequate sunlight and charging efficiency. Generally, the range of ±20° from true south is a good position.
7. Solar Panel Output Power
Solar panels are typically made up of multiple solar cells connected in series. The required capacity depends on the total power consumption of the lighting source and transmission components, as well as the local solar radiation energy.
Generally, the output power of the solar panel should be more than 3-5 times the power of the light source. In areas with abundant sunlight and shorter lighting durations, it should be 3-4 times, while in areas with poor lighting conditions and longer lighting durations, it may need to be 4-5 times.
8. Daily Load Working Hours
Today’s solar street lights are designed with intelligence; they are usually brightest during the bustling early night, operating at full power, while during late night, the brightness reduces to about 50% of the power. When calculating, it is essential to equate this to full power working time.
9. Controller Component Charging Efficiency
The charging control methods for controllers generally include PWM and MPPT, and their corresponding charging efficiencies vary. PWM has strong charge, balance charge, and float charge in three stages, which can effectively solve issues of battery not being fully charged and shortening battery lifespan; however, its charging efficiency is lower than that of MPPT.
MPPT solar controllers go through MPPT charging, constant voltage equalize charging, and constant voltage float charging phases, enabling the system to charge the battery at maximum power, thus achieving high charging efficiency. However, the cost is several times to dozens of times that of PWM, and it depends on individual needs while relevant parameters can be based on specific components.
10. Controller Component Drive Efficiency
This serves as a reference for calculating LED head power and setting the driving current for the LED head.
11. Battery Conversion Efficiency
Different batteries correspond to different efficiencies. Today’s solar street lights are typically designed as integrated systems using lithium iron phosphate batteries, which have significantly higher conversion efficiencies than traditional lead-acid batteries, generally ranging from 92% to 95%.
12. Comprehensive Loss Compensation Factor
This generally considers factors such as line loss, dust, shading, battery coulomb efficiency, and temperature effects. When calculating relevant parameters, values are typically taken between 1 and 1.4.
The above parameters related to installing solar street lights have been shared here. Besides these parameters, other related factors include the accumulated depth of battery discharge. For commonly used lithium batteries, it is advisable to maintain a discharge depth of around 90%. Understanding these parameters can help merchants better understand customer needs and select suitable configurations for installation environments.
