A solar street light, an outdoor light fixture, harnesses the radiant power of the sun to power its light engine. Solar street lighting is an affordable, practical and efficient alternative to grid-tied lighting. It can improve visibility, safety, or pedestrian security.
Grid-independent operation means that there is no need for underground wiring or trenching. Solar street lights are the first choice for installations in remote and harsh locations. Zero carbon emissions, minimal energy bills, and minimal ongoing cost. Even in urban areas these appealing advantages of solar street lamps appeal to a variety of outdoor lighting applications, such as illuminations of secondary roads and residential streets, driveways or pathways, parking lots, or building perimeters.
A typical solar streetlight system is composed of a panel, a controller, a battery, and a light bank.
A major component of a solar street lamp is the solar panel. The primary function of the solar panels is to convert sunlight from electricity. This is then stored in solar rechargeable battery.
Solar panels are made up of multiple individual solar cells. We will not be covering thin-film panels because they are less efficient and are not up to the task. There are two types: mono-crystalline or poly-crystalline solar cells. Mono-crystalline solar cell conversion rates are much better suited for solar street light performance than poly-crystalline.
Solar Charge Controller
The heart of the sun's solar system is the controller. This controller decides when to turn on the lighting or charge. Smart controllers have three main functions: dimming, lighting and charging. The smart controller stops the solar battery overcharging and undercharging. It charges the battery continuously during the day by receiving solar energy. The controller then uses the stored power during the night to run the LED street lamps. Smart controllers can handle single loads as well as multiple loads.
Smart solar controllers offer excellent energy generation, performance optimization, and monitoring of each streetlight unit via cloud-based software. The smart controller comes with a dedicated software and a communication network that allows for proactive maintenance and control of the entire streetlight network.
They can be broken down into three groups: simple ON/OFF, pulse width modulation or (PWM), as well as maximum power point tracking (MPPT). The ON/OFF control prevents overcharge or undercharge of the battery and also prevents reverse current. PWM is a control of the amount of current charged the battery. It also provides trickle charging. MPPT, a more advanced approach, is often used in solar street lighting systems for high efficiency battery charging.
Solar Rechargeable Battery
The solar battery can be described as an electrical battery. The solar battery stores electricity from the sun during the day to power the LED lamp at night. Battery life and capacity are very important because they provide back-up power for low energy times - days without sunlight. A smart solar street lighting system with a temperature probe will monitor and optimize the performance of the battery (battery temperature and discharge voltage) in order to extend battery life.
Two of the most popular battery technologies in solar streetlights are lithium-ion or lead-acid.
A cycle life of 1500 to 2500 cycles for lead-acid batteries, a life expectancy of 3 to 5 year, and a depth-of-discharge (DOD) of 70-90. The energy density ranges from 30 Wh/kg down to 50 Wh/kg depending upon the lead density. Lead-acid battery capacity is reached at 100% in 12-16 hours. This is due to solar radiation which can last many hours and the slow charge rate that allows efficient charging.
Lithium ion battery have the highest energy density, and the longest life span of any battery chemistries. The lithium-ion-battery is a lithium ion-transfer cell. In this case, lithium ions, which are the working ionic components of electrochemical reaction, shuttle between anode (or cathde) and cathde (or electrolyte).Tags: solar streetlight