Charging a capacitor using a 4V solar panel

Click For Summary

Discussion Overview

The discussion revolves around the behavior of a capacitor when charged by a 4V solar panel, particularly focusing on whether the capacitor will stop charging at 4V or continue to draw current indefinitely. Participants explore concepts related to capacitor ratings, charging dynamics, and potential circuit designs for efficient energy transfer.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Some participants propose that a capacitor will charge up to the voltage of the source, regardless of its voltage rating, suggesting that a 4V solar panel will charge a capacitor to 4V.
  • Others argue that capacitors do not inherently stop drawing current when they reach a certain voltage, leading to concerns about potential damage if connected to a higher voltage source.
  • A participant mentions the use of a diode to protect the solar panel when its output drops below the capacitor's charge.
  • One participant suggests using higher voltage components and a buck/boost converter for more efficient energy management, referencing the SEPIC topology.
  • Another participant shares an experimental observation of charging a capacitor through a resistor, noting the relationship between voltage, current, and power in the context of solar panel performance.

Areas of Agreement / Disagreement

Participants express differing views on the charging behavior of capacitors and the implications of voltage ratings. There is no consensus on whether a capacitor will stop drawing current at a specific voltage or the effects of connecting it to a higher voltage source.

Contextual Notes

Some statements rely on assumptions about circuit behavior and component interactions that may not be universally applicable. The discussion includes references to specific circuit designs and experimental setups that may not be fully detailed.

Who May Find This Useful

Individuals interested in electronics, solar energy applications, capacitor behavior, and circuit design may find this discussion relevant.

Clancy John
Messages
1
Reaction score
0
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.
 
Last edited by a moderator:
Engineering news on Phys.org
Artlav said:
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
 
Clancy John said:
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.
 
Clancy John said:
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?
 
phinds said:
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.
 
Averagesupernova said:
That's what I was wondering.
Well, can a 4V source produce more than 4V?
 
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.
PVcurve32W14.8V2.2As.jpg
 
  • Informative
Likes   Reactions: Tom.G

Similar threads

Replies
6
Views
4K
Replies
28
Views
4K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 17 ·
Replies
17
Views
16K
  • · Replies 10 ·
Replies
10
Views
3K
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 13 ·
Replies
13
Views
7K
  • · Replies 15 ·
Replies
15
Views
3K