Supercapacitors Power Round-the-Clock Photovoltaic Lighting System (.PDF Download)

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Delivering round-the-clock light, this solar photovoltaic (PV) system works for 15 years maintenance-free. Off-grid design enhances its usefulness during grid failure.

The block diagram of the system features the following:

• Solar day lamp (DL): It provides light in the daytime. It also charges the supercapacitors. These capacitors can handle daily charge/discharge cycles for years without any degradation in performance.
• Night lamp (NL): It consists of a dc-dc converter module that’s powered by the charge stored in these capacitors. The converter’s output powers two of the NL’s LEDs. The NL runs for a few hours after sunset.
• Joule Thief circuit: It extracts the residual charge from the capacitors and powers the zero lamp (ZL), which remains ON throughout the night.