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Designing Reliable Solar Street Light Systems with Optimized Battery Management
In-depth Analysis of How Battery Aging Impacts Solar Street Light Systems
Batteries wear out due to cycling of charge/discharge of batteries during solar operational systems. Exposure to debilitating temperatures + being overly discharged (taking too much energy) can be harmful. Extreme internal temperatures can cause chemical breakdown of batteries causing as much as 20% loss of usable power. Additionally batteries can be damaged from low state of charge (deep discharge) battery cycling. From an operational perspective, many battery power lights/license plate recognition systems do not operate as designed. For example, lead acid batteries have an operational lifespan of 2–5 years, while lithium ion batteries have a lifespan of 5–10 years. Thus, battery systems with quality battery management systems (BMS) can effectively manage system performance by monitoring and managing battery cell voltage and state of charge (SOC) to avoid excessive discharge of the battery system and provide cell voltage balance to maximum performance of the system. Operating BMS is vital for the operational performance of the street light battery module.
Protocols for Practically Monitoring, Inspecting, and Replacing Batteries
Establishing battery management alerts for tracking voltage, temperature, and charge levels is a reasonable approach, and alerts can catch potential problems before they escalate, such as a 12V system that stays below 11 volts for a prolonged period. Every three months, perform a visual inspection for signs of corrosion, bulging casings, and leaks from seals. Special consideration should be given to facilities located near saltwater, as the corrosion rate is approximately 30% greater in the presence of saltwater. Battery capacity should be replaced when it drops below 70% of its original rating. Lithium-ion models have a recommended replacement time of 5 years. Keep things running smoothly with monthly maintenance; it avoids unexpected problems and costs less to maintain over time. When ordering replacement stock, always request batteries with higher temperature ratings.
Solar Panel Cleaning Strategies and Shade Management for Optimal Performance
Cleaning Schedule Considerations Based on Climate for Solar Street Light Installations
Solar panels are affected negatively by contaminants in the environment such as dust, bird waste and tree pollen. Solar panels are more affected by these contaminants in arid environments, so an optimal cleaning regime is a routine cleaning every month. In flush coasts and salt marshes, solar panels become rust susceptible from salt. Cleaning is required every 3 months to reduce the tendency for rust. Cleaning should not be done in the afternoon when the sun is strong. Cleaning solar panels should be done in the early hours, so the sun is not too strong and the risk for cracking the glass is reduced. Solar panels are susceptible to increased contamination due to exhaust fumes from cars. Urban locations require maintenance on a more regular basis, so every two weeks is a good cleaning regime to reduce the black soot on the to solar panels. Solar panels are negatively affected by the environment more so than other forms of technology. Dust on solar panels will cause reduced efficiency and increased temperatures. The basis of the range of technology negatively affected Luzzaro and the solar panels.
Spring causes dust to be highly inefficient.
Summer causes increased temperatures to the solar panels.
Desert sand cause increased temperatures and abrasiveness to the glass.
Only use neutral pH soaps when cleaning solar panels. Cleaning should be scheduled when the efficiency of the solar panels is less than 5% for a sustained period of time. Cleaning should be done in conjunction with tree pruning. This is critical in the winter months when the sun is lower in the sky.
Prioritized Defense of Fundamental Components
The core components of solar street lights systems are negatively affected by environmental exposure such as humidity, dust, salt, and temperature fluctuations. These factors increase the rate of wear on the systems, especially the LED lights, charge controllers, sensors, and wiring. Protecting the systems by preventing problems before they start is needed to preserve positive performance and decreased lifecycle costs.
Inspection Procedures for the LEDs, Charge Controllers, Sensors, and Wiring of Solar Street Light Systems
Every month, a visual and functional inspection should be done to capture the following:
A visual inspection of the LED lens for cracking, condensation, and insect infestations.
The insulation integrity on wiring at the junction boxes and terminations.
The responsiveness of motion and ambient light sensors.
The charge controller should be checked to be in normal charging, floating and load regulation indicator positions.
Document any issues as they arise. These include odd discolourations on the PCB, loose connections, and odd sensor responses. Minor issues should be rectified before they escalate to major issues which could affect the performance of the entire system.
Best Practices for Weatherproofing and Corrosion Resistance for Humid and Coastal Environments
The salt air present in coastal areas increases the speed of corrosion on metal contacts, penetrating them at a rate 5 times greater than that of inland corrosion. Some strategies that help manage this include:
The use of conformal coating on bare PCB to repel moisture.
The use of stainless steel bolts and other fasteners, as well as IP68-grade enclosures are recommended on all electrical components.
The use of sacrificial anodes installed on structural poles as a means of controlling other forms of electrochemical corrosion.
The use of marine-grade wiring, having silicone or cross-linked polyethylene (XLPE) insulation, is strongly recommended.
In inland areas where humidity is high, the use of ventilated areas having a hydrophobic membrane which allows moisture to exist as a vapor in the air is strongly recommended.
Utilize Smart Monitoring and Data-Driven Maintenance To Avoid Unforeseen Failures.
Smart monitoring shifts the paradigm from reactive maintenance to "smart" and proactive maintenance. During maintenance of solar street lights, rather than waiting for a failure, maintenance teams can use smart monitoring, which is a form of proactive maintenance. Each smart unit has a set of intelligent sensors that monitor numerous variables, including battery status, power generation, led(s) degradation, and other parameters that may negatively affect the performance of the solar street lights , including external elements . Each of the solar street lights has a data analytics software that can analyze the data and detect anomalies that may go undetected. Data analytics software, for example, can monitor battery performance and stability of battery voltages, which can indicate an imminent battery failure. Data analytics software can also identify an increase in energy generation during the daytime, which may indicate that an obstruction is present that is limiting solar exposure to the solar panel. In the research journal, Sustainable Facilities Journal (2023), it shows that cities can save 25% on maintenance costs, while also extending the lifespan of the solar street lights, when cities transition from fixed interval maintenance to reactive maintenance. In addition, cities have also shown to save maintenance repair costs during out of bound work hours ( i.e. after hours, weekend, etc.) when street lights are commissioned.
FAQ
Why is battery management important for solar street lights?
Effective battery management is important to ensure that the solar street light batteries make best use of the battery lifespan, and ensure that battery failure ( i.e. complete loss of functionality of the solar street light ) is not experienced.
How frequently do solar panels need to be cleaned for optimal performance?
The cleaning frequency for solar panels depends on the local environment. In dry regions panels should be cleaned every month for optimal performance, while in coastal regions cleaning should be done every 3 months.
What environmental conditions shorten the life span of solar street lights?
The life span of solar street lights is reduced by temperature changes, humidity, dust, and salt spray. These environmental conditions impact the life span of solar street lights by damaging the LEDs and wiring.
What is the benefit of smart monitoring for the maintenance of solar street lights?
With smart monitoring, maintenance can be performed when necessary to keep the solar street lights in an optimal working condition, which lowers maintenance costs and prolongs the street lights' life.