Universal Off-Grid Microinverter for Ultra-Low Cost Energy Access
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Prabhu, Navami Srinivas
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Abstract
Energy access is a fundamental driver of socio-economic development, and yet, as of 2023, around 760 million people worldwide lack access to electricity, with significant deficits in regions like Sub-Saharan Africa (SSA). With daily incomes as low as $2/day in Sub-Saharan African regions, energy providers and entrepreneurs grapple with low return rates on their investments, further augmenting energy access challenges and shedding light on the tight coupling between energy access and poverty levels. Throughout the years, traditional solutions such as grid extensions, microgrids, and solar home systems have struggled to scale in energy access markets due to high capital and operating costs, amplifying the energy crisis in rural Africa and Asia, and emphasizing the need for an economical and productive solution that fundamentally caters to low-income households, to improve access to energy while reversing poverty. This research introduces the 'AC Plug', an off-grid, ultra-low cost, scalable, plug-and-play solution, designed to interface with pure PV, pure battery or hybrid systems, depending on cost considerations and availability. The AC Plug can support both resistive and electronic loads, such as phones, laptops, televisions, fans, electric kettles, LEDs, incandescent lamps, microwave ovens, water pumps, and so on, rated up to 1kW, thereby capable of powering appliances across Tier 1 to Tier 4 categories, without the use of large inductors or DC-link capacitors. The proposed microinverter can operate across a wide input voltage range of 10V to 40V, to generate either a square wave or modified square wave AC output at 50Hz or 60Hz, offering tremendous flexibility. This work presents the structure, operating principle, design, and control scheme of the proposed topology. A 1kVA/240Vac hardware prototype is built and tested to validate the system behavior and performance under various operating conditions. The microinverter addresses the technical and economic challenges observed in existing approaches by using low-cost, robust active and passive elements, with straightforward control, making the setup benign, user-friendly and safe to operate, particularly for users in SSA with limited technical understanding of the system.
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2024-08-28
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