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T-00424: An Efficient Method for Solar Charging of Batteries

Background: The significance of developing new types of energy conversion and storage systems is apparent by the ever-increasing human reliance on energy-based appliances, the speedily diminishing fossil fuels and the continuously growing environmental concerns. Solar cells offers a captivating option for directly photo-charging lithium-ion batteries. Currently, the photo-charging of batteries using solar cells, is unviable due to design complexity, and high cost associated to it.

Description: An efficient photo-charging approach, where a solar cell effectively charge a battery using a DC-DC voltage boost converter have been developed. Interestingly, the converter boosts the low input voltage of the solar cell to charge the battery and further offers advantages including, maximum power point tracking (MPPT) of solar photovoltaics and battery overvoltage/undervoltage protection. For this, there were two approaches; Discrete and integrated charging. As far as for discrete charging, highest reported overall efficiency of 9.36% and average storage efficiency of 77.2% at 0.5 C discharge, was achieved for tested device. As for integrated charging, a solar cell-battery integrated device was developed and charged using the MPPTbased DC-DC voltage boost converter. Overall efficiency as high as 4.2% with storage efficiency as high as 81.5% was achieved for tested device.

Advantages: 

  • This invention, potentially offers a cost-effective solution due to its lower complexity in design. 
  • With improved lifetime stability, this photo-charging solution can be employed in low powered portable electronics, which can appreciably enhance its reliability.
  • It also has the potential to be used in sensor network applications, where continuous working is required without further monitoring.