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solar panel charging a 5V supercapacitor

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helix1

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Hi,
I am wanting to use a small solar panel to slowly charge up a 0.47F supercapacitor that is rated 5V. My solar panel outputs up to 7.5V at max sunlight exposure but often is much less than this, and the current is typically very small. My question is: will the solar panel damage the supercapacitor when it is exposed to maximum sunlight as its voltage will be above the max rating on the capacitor even though the current will be very small? If so, why?
Thanks in advance... :)
 
Yes. Voltage over the SuperCapacitor's rated voltage risks blowing a hole through the dielectric, which will destroy the S.C.

Use a 4.7V or 5.1V Zener as a shunt regulator (across the S.C.) to limit the charged voltage.
 
Q=C*U
I=Q/t

I don't know much about solar panels but I am guessing they have low power output
and if so when the cap is not full voltage at full exposure will fall to whatever voltage
is on the cap. So you need to limit voltage only when the cap is full and as suggested
a zener in parallel will do this and also won't interfere when the cap is not full,
but I wonder if you should use a limiting resistor?
 
...,
but I wonder if you should use a limiting resistor?

Not needed. The solar panel is SO current-limited than no other resistor is needed.
 
Thanks. So if the voltage only needs to be limited when the cap is full, does that mean that if a circuit is attached that is set to discharge the cap once it is above a certain voltage (less than the full rating on the cap), the protection Zener is not needed?
 
Thanks. So if the voltage only needs to be limited when the cap is full, does that mean that if a circuit is attached that is set to discharge the cap once it is above a certain voltage (less than the full rating on the cap), the protection Zener is not needed?
That is correct.
 
That is correct.

With one qualification: the current draw of the circuit must exceed the peak current output from the solar panel, otherwise the capacitor voltage will continue to increase even after the circuit is triggered.
 
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