Types of Solar Street Lamp Light Sources

Solar street lamps use the photovoltaic effect of solar cells. The solar cells absorb solar photon energy to generate electricity in the day, which is stored in the battery through the controller. When night falls or the light around the lamp is dim, the battery supplies power to the light source through the controller. Solar street lamps are composed of the following parts: solar panels, solar controllers, battery packs, light sources, light poles and lamp housings, as shown in the figure below. The light source is a very important part of solar street lamps. How much do you know about the types of solar street lamps light sources? Let's take a look!

1. Low-pressure sodium lamp

Compared with some common light sources, low-pressure sodium lamps can save energy by more than 50% at the same luminous flux and illuminance. Since the light-emitting tube of the low-pressure sodium lamp is sealed in a high-vacuum glass shell coated with an infrared reflective film, its luminous efficiency is basically not controlled by the ambient temperature, and its radiation spectrum is pure, stable, and free of stray light. Coupled with high-quality electronic ballasts, low-pressure sodium lamps are easier to use under various power conditions, especially suitable for solar street lamps in special environment areas such as tunnel lighting and plateaus.

2. LED lights

LED is called the fourth-generation lighting source or green light source, which has the characteristics of energy saving, environmental protection, long lifespan and small size. It is a semiconductor that can convert electrical energy into light energy, using electroluminescence. Almost all the spectrum of white light LED is concentrated in the visible light frequency band, and its luminous efficiency can exceed 140lm/W. The luminous efficiency of ordinary incandescent lamps is 13lm/W, and the lifespan is less than 2000 hours, the luminous efficiency of spiral energy-saving lamps is 70lm/W, and the lifespan is less than 8000 hours, and the T5 fluorescent lamp is 94lm/W and the lifespan is about 10,000 hours. The luminous efficiency of a white LED with a diameter of 5 mm can theoretically exceed 150lm/W, and the lifespan can be greater than 100,000 hours. LED is a low-voltage power supply, the most easy to match the power supply of solar power. Other lamps require a larger boost range, power conversion loss is large as well as the electromagnetic interference. The luminous efficiency of the LED light source is more than twice that of ordinary high-pressure sodium lamps and energy-saving lamps, so to reach the specified brightness, only half of the original street lamp configuration is needed. In this way, the cost of solar street lamps is almost cut in half, and the service life of solar LED street lamps is also obtained. More and more solar street lamp manufacturers use LED as light source to achieve better performance of the lamp, although it's more expensive.

3. High pressure sodium lamp

Unlike low-pressure sodium lamps, high-pressure sodium lamps use DC 24V (12V) input to the electronic ballast, output low-frequency (or high-frequency) to the bulb, and high-voltage pulses to start the lamp. Since it is an electronic ballast for lighting, it is beneficial to the lifespan of the bulb and can extend the lifespan of the bulb by more than 30%.

4. Induction lamp

Since its starting voltage and current are basically the same as the normal working voltage and current, it is especially suitable for the use of solar street lamps and is a new type of light source specially developed for solar light systems. Because there is no filament in the bulb body, it has a very long service life, up to 80,000 hours. In addition, because the light-emitting coating of the bulb is a three-primary color powder, the light is soft and the glare is greatly reduced. Compared with other lamps, high-frequency plasma induction lamps can directly save electricity costs, even 20%-30% lower than energy-saving lamps. The high-frequency electrodeless discharge lamp requires no or less maintenance, has high reliability, and has a service life of up to 80,000 hours.

5. Energy-saving lamps

Energy-saving lamps are characterized by low current, which can greatly extend the discharge time of the battery. The energy conversion rate is much higher than that of incandescent lamps, which saves electricity and can also be said to reduce greenhouse gas emissions. However, there is mercury pollution during the production process, and it is easily broken and difficult to transport.

6. Metal halide lamp

The biggest feature of the metal halide lamp is its extremely high luminous efficiency, with the luminous efficiency as high as 75-85Lm/W. When the light is normal, the heating condition is reduced. Since the spectrum of the metal halide lamp is based on the continuous spectrum with dense linear spectrum, the color rendering index is particularly high, that is, the color reduction effect is very good, reaching more than 90%. In addition, the color temperature of the metal halide lamp is high, up to 5000～6000K. The metal halide lamp has a relatively short lifespan due to its high brightness and small size, generally between 2000h and 18000h. The disadvantage of the metal halide lamp is that it is difficult to start.