Design of Sustainable, Efficient, Safe, and Economically Viable Solution for Solar Street Lighting System

<p>The combination of solar and LED lighting has enabled interest in the municipalities and governing authorities to consider solar LED lighting as economical and as an efficient choice to lighten streets. Stand-alone/decentralized solar solutions are very popular for these applications. However, these solutions suffer from poor performance due to dust accumulation and difficulty in accessing PV panels for regular maintenance. Further, these solutions need design change in pole’s mechanical structure, often built with customized PV panels and also oversized to take care of no-sunshine days i.e. 3−7 days. To overcome these drawbacks, centralized 230V AC or 48V DC systems have been installed in the field. However, 230V AC or 48V DC systems are inefficient either due to multiple power conversions in the power delivery path or higher distribution losses resulting in higher panel and battery capacities and hence higher cost. This paper proposes unique power architecture i.e. Centralized DC solar street lighting system on 220V DC distribution line, which is 15−20% more energy efficient than inverter based AC centralized solution. This efficiency gain results in less material usage such as lead (in battery), silicon, supporting metal frames, packaging material etc. leading to more environmentally friendly than existing technologies and also lower system capital cost. Further there is also possibility for grid interconnectivity, which will further lead to reduction in battery capacity and hence payback period will be lowered. AC grid system needs accurate prediction system to optimize green energy utilization. With AC backup, centralized system can be designed with only 25%−50% oversizing against 300%−500% in conventional system. Similarly to reduce the cost of electronics, Dual Function Converter (DFC) has been proposed. This results in reduction of number of components, footprint and controller size in centralized system by nearly 50% and enhances reliability by a factor of 2. The proposed solution results in lower solar array and battery capacities, smaller electronics footprints and lower demand of material resource in street lighting poles.</p