Integrated Solar Street Light

INTEGRATED SOLAR STREET LIGHT

Integrated solar street lights are also known as split solar street lights or All-In-Two solar street lights.  These street lights are integrated by the solar panel system and lamp fixture.  Unlike All-in-One street lights, the solar panels come as a separate unit and only the battery and the luminary are integrated into a single unit but in some of the integrated solar street light fixtures that use lead acid batteries, the battery comes as a separate unit in a box.  Integrated solar street lights operate without motion sensors and there are two types of MNRE models available; Model-I operates from dusk to dawn at  full brightness while Model-II illuminates the first four hours at full brightness and then at a lower level until sunrise.  The split solar street lights are commonly used not only on public roads but also for gardens, parking lots or any large open areas.

Features of Integrated Solar Street Lights

• Automatic dawn to dusk feature
  
• Dimming option
  
• Well suited for all climate conditions
  
• High efficiency LiFePo4 battery
  
• Economic and cost effective
  
• Longer backup
  
• Panel direction can be changed
  
• Faster charging since the solar panels used are bigger
  
• Low maintenance
  
• IP65 waterproofing
  
• Durable metal or ABS body

Controllers used in Integrated solar street lights

MPPT (maximum power point tracking) controller is an electronic DC to DC converter, taking higher voltage DC input from solar panels, changing to high-frequency AC and converting back down to DC voltage needed to charge batteries. MPPT controllers are created bearing the fact in mind that due to weather conditions the solar panel puts out variable output and are capable of matching the voltage the solar panels produce to the voltage of the battery in order to maximize charging efficiency.

PWM (pulse-width modulation) controller draws out current from the solar panel at just above the battery voltage and acts as a switch between the solar panels and the battery. PWM is designed to determine the amount of charge going to the battery from the solar panel and taper off charging as the battery becomes full. Though PWM controllers are cheaper and believed to be reliable over the years, MPPT controllers are regarded as more sophisticated and efficient comparatively.

Solar panels used in Integrated solar street lights

Both Monocrystalline and Polycrystalline solar panels are used in integrated solar street lights.  Monocrystalline panels are made out of a single crystal structure of pure silicon while polycrystalline panels are made of fragments of silicon which are melted together to form the wafers.  Monocrystalline solar panels are relatively more expensive although they are highly efficient in their performance due to the silicon purity.  Polycrystalline solar cells are more affordable since there is hardly any silicon wasted during the manufacturing process.

Batteries used in Integrated solar street lights

LiFePo4 batteries are commonly used due to their high efficiency although some integrated street light fixtures still use Lead Acid batteries.  Lithium battery can be integrated into the luminary due to its compact size; on the other hand, lead acid battery of the same capacity as the lithium battery is up to four times larger in size and cannot be attached as a part of the luminary.  LifePo4 batteries guarantee a longer lifespan and constant output power compared to their lead acid counterparts.

Light source used in Integrated solar street light

LED lights are used in integrated solar street lights due to their energy efficiency and instantaneous illumination.  LED lights produce almost no heat and are known to have great color rendering index, making it the best choice for street lighting.  LED lights offer dimming option, which in turn helps light fixture to have a longer life.  LED lights are capable of functioning even on low voltage and work well in different operating temperatures.

Installation of Integrated street lights

Integrated solar street lights can be installed either on a pole or a wall.  The installation process is easy but the time to install may be slightly longer compared to the installation of All-in-One solar street lights.  Before erecting the pole, the solar panel is fixed into the arm as per the instructions given by the manufacturer, then luminary is fixed and then the arm can be fit into the pole.  The flat ground selected to install the pole should be dug at least 3 feet deep.  After placing the pole into the hole and erecting it, secure it to the ground by using concrete.  If there are multiple lights being installed, ensure they are installed at an even distance to supply adequate brightness to the entire area uniformly.  Since the direction of solar panels can be adjusted according to the direction of sunlight, make sure the right spot is chosen for installation.

Maintenance

Integrated solar street lights operate based on dusk to dawn feature and are automatic in nature, so very minimal maintenance is required after installation.  To increase the efficiency and brightness, it is important to do basic cleaning and maintenance whenever required.  The solar panels are placed at an angle to avoid water stagnation; however, the rain water helps in cleaning the solar panel by washing away most of the dirt and dust accumulated on the panels.  Most of the manufactures offer a minimum of 1-2 years of warranty for integrated solar street lights.  The installation cage and the lighting fixture should be checked on an occasional basis to look for any parts that may need replacement or repair.

Advantages

• Two MNRE models available to choose with automatic dawn to dusk feature
• Direction of solar panel can be changed so as to absorb maximum sunlight
• Dimming option to save energy
• Tilted panels angle to avoid water stagnation
• Since the solar panels are bigger, they get charged faster
• Longer backup even during low sunlight days and performs even on low voltage

Disadvantages

• Installation time is more compared to All-In-One solar street lights.
• No motion sensor and night-long illumination may not be needed always
• Cable work required, though minimal, from panel to luminary
• Not compact, hence the light fixture takes slightly more space compared to All-In-One solar street lights
• Priced at a higher range compared to All-In-One solar street lights