Supercapacitor‐assisted LED (SCALED) technique for renewable energy systems: a very low frequency design approach with short‐term DC‐UPS capability eliminating battery banks

Abstract

The fluctuating nature of solar energy necessitates suitable energy storage systems. Compared to typical battery banks, supercapacitors offer longer cycle life eliminating the need to replace them regularly. However, compared to a typical maximum power point tracking controller, where the battery bank and resistive load fed by a switch-mode DC-DC converter allows impedance matching for maximum power transfer, a supercapacitor bank's significantly large capacitive load does not permit the typical impedance matching for maximum power transfer. This study compares the theoretical difference between battery versus supercapacitor energy storage, and highlights of the supercapacitor-assisted LED converter technique in achieving high-efficiency renewable energy-based DC-microgrid systems. (a) PV current versus voltage characteristics with directly coupled operating point, (b) Current-voltage variations with irradiance, (c) Power versus voltage curve

Supercapacitor Assisted Hybrid PV System for Efficient Solar Energy Harnessing

“…This technique uses the advantage of a large time constant when a supercapacitor is connected to an RC circuit. Based on this concept, several SC assisted circuit topologies such as SC assisted light-emitting diodes (SCALED) [20], SC assisted low dropout regulator (SCALDO) [25] and SC assisted surge absorber (SCASA) [26] have already been developed. The fundamental background of this theory is summarized as follows.…”

“…The recent development of supercapacitor (SC) technologies has enabled the use of SCs as an energy storage device for standalone PV systems [14,15]. Compared to batteries, SCs have higher power density and longer cyclic life, making them better suited for selfsustainable and low-maintenance systems [16][17][18][19][20][21]. When an empty capacitor charges to a voltage of by delivering charge , the capacitor stores…”

“…This is a 50% energy loss compared with the electrochemical battery, where a battery stores an energy amount of . In addition, authors of [20] have studied the possibilities for impedance matching of a typical standalone PV system by connecting an SC bank at the output of the DC-DC converter, replacing the battery bank. Results indicate that tracking the MPP using the impedance matching technique is extremely difficult for such a system because of the rapid variation of the impedance across the SC bank with state of charge (SOC).…”

Study on energy efficiency improvement strategy of photovoltaic-hybrid energy storage DC microgrid considering green energy saving concepts

“…The DC microgrid, as a platform connecting these components, has a direct impact on the performance of the overall system. This study focuses on how to implement effective energy-saving measures in the design and operation of PV DC microgrids [8], which include optimizing the system configuration, improving the energy conversion efficiency, and reducing energy loss by using intelligent control systems [9].…”

Maximum Power Point Tracking of an Off-Grid Photovoltaic System Consisting of a Series Connected Supercapacitor with a Step-Down Converter

“…This theory shows how to improve the efficiency of a system by inserting a useful resistive load in a series configuration into an SC charging loop. Several novel circuit topologies such as SC assisted low drop-out regulator (SCALDO) and SC assisted light-emitting diodes (SCALED) were introduced and developed over the years as possible applications of the SCALoM theory (11,12). The SC-battery hybrid off-grid PV system is a novel application of the SCALoM theory developed and introduced recently (13).…”