It can be used conveniently as a back up power supply or emergency power supply for VTR, communication devices, portable electronic calculators, watches, computers and office automation devices and also as {HEAD ~ solar cells} and cells for {TAIL ~ solar systems} 
It can be used conveniently as a back up power supply or emergency power supply for VTR , communication devices , portable electronic calculators , watches , computers and office automation devices and also as { HEAD ~ solar cells } and cells for { TAIL ~ solar systems }
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