Charging a capacitor using a 4V solar panel

[Clancy John]

Will a 4V solar panel connected to a 100V rated capacitor stop charging the cap at 4V or will the cap keep pulling ad infinitum? Seems like the capacitor has no knowledge of the notion "I am full so stop drawing current" else they would not get destroyed if the solar panel was 500V instead. I know how to protect the panel with a diode when the panel drops output below the caps charge.

 

[rbelli1]

the existence of such ICs do provide a new direction for searching.

Take the datasheet block diagram and make one of your own. Use higher voltage components. I would suggest using a canned switcher for that part of the circuit. Something buck/boost would be best. Search for SEPIC. There will be a "black box" somewhere in the diagram for the main MPPT controller. That special sauce is described in usually fairly good detail in the datasheet. Drop in a micro program it and you're good to go.

BoB

 

[meBigGuy]

Sorry to go off-topic but will a 4V solar panel connected to a 100V rated capacitor stop charging the cap at 4V or will the cap keep pulling ad infinitum? Seems like the capacitor has no knowledge of the notion "I am full so stop drawing current" else they would not get destroyed if the solar panel was 500V instead. I know how to protect the panel with a diode when the panel drops output below the caps charge.

The capacitor will charge up to the voltage on the source. Doesn't matter what its rating is. Read a little about RC circuits on wikipedia to make it clear.

 

[phinds]

Sorry to go off-topic but will a 4V solar panel connected to a 100V rated capacitor stop charging the cap at 4V or will the cap keep pulling ad infinitum? Seems like the capacitor has no knowledge of the notion "I am full so stop drawing current" else they would not get destroyed if the solar panel was 500V instead. I know how to protect the panel with a diode when the panel drops output below the caps charge.

A cap does not care what voltage it's rated at as long as you don't exceed that rating. 4V hardly comes close to exceeding the rating of a 100V cap. How could you expect a 4V source to produce more than a 4V charge on a cap?

 

[Averagesupernova]

A cap does not care what voltage it's rated at as long as you don't exceed that rating. 4V hardly comes close to exceeding the rating of a 100V cap. How could you expect a 4V source to produce more than a 4V charge on a cap?

That's what I was wondering.

 

[phinds]

That's what I was wondering.

Well, can a 4V source produce more than 4V?

 

[Opera]

Old thread, but you can convert that 4V to a higher voltage at lower current minus some loss in electronics. Power remains about the same.

As to what charging a capacitor with a solar panel looks like, I recently did this experiment to test a solar panels power point voltage. I am simply charging a capacitor thru a 0.5 ohm resistor. YELLOW is the volts climbing to about 20V where the current BLUE eventually stops. The top flat portion is the panels Isc till it drops. RED is voltage multiplied by the current, power. That peak is the voltage where you can get the most power, Impp &Vmpp. It is nice to see science work just like the data sheets say.