Hey,
I am interested in starting up some various hobby projects, and have gotten the interest for small solar cell driven devices. I have a masters degree in Computer Science and are currently working with FPGA and digital ASICS, but I want to increase my analog electronics knowledge.
Currently I am planning to make a cap with solar cells, capable of charging a cell phone or similar through USB.
I have been looking around for a electrical model of a solar cell and found http://www.pvresources.com/en/solarcells.php
This indicates that the maximum power output is achieved just at a little bit lower current than the short circuit current. Is this something that I should be thinking about when I design my circuit?
I think for charging a smartphone it would be enough with around 1-2 W. In my case, through the USB port at 5V. But there are various solar cells out there giving almost any voltage/current combination. I am assuming that the voltage needs to be regulated.
Which of the following methods are preferred to get the most charging power (less wastee?
1) 6V/250mA and using a linear regulator to get 5V. This would waste (6-5)*0.25 = 0.25 W.
2) 12V/125mA and using a switched regulator (buck converter?). Can I convert that to 5V and can that give me more than the 125mA I am putting in? Then I can normally get ~90% efficiency, right? That wastes 12*0.125*0.1 = 0.15 W.
Number 1) is alot easier, involving only a two capacitors and a regulator. Number 2) needs more components
In my application, does it matter if I would connect solar cells in series to get voltage or parallel to get current?
I have a number of other questions aswell, but I figured I could see what you say regarding this first
Thanx!
I am interested in starting up some various hobby projects, and have gotten the interest for small solar cell driven devices. I have a masters degree in Computer Science and are currently working with FPGA and digital ASICS, but I want to increase my analog electronics knowledge.
Currently I am planning to make a cap with solar cells, capable of charging a cell phone or similar through USB.
I have been looking around for a electrical model of a solar cell and found http://www.pvresources.com/en/solarcells.php
This indicates that the maximum power output is achieved just at a little bit lower current than the short circuit current. Is this something that I should be thinking about when I design my circuit?
I think for charging a smartphone it would be enough with around 1-2 W. In my case, through the USB port at 5V. But there are various solar cells out there giving almost any voltage/current combination. I am assuming that the voltage needs to be regulated.
Which of the following methods are preferred to get the most charging power (less wastee?
1) 6V/250mA and using a linear regulator to get 5V. This would waste (6-5)*0.25 = 0.25 W.
2) 12V/125mA and using a switched regulator (buck converter?). Can I convert that to 5V and can that give me more than the 125mA I am putting in? Then I can normally get ~90% efficiency, right? That wastes 12*0.125*0.1 = 0.15 W.
Number 1) is alot easier, involving only a two capacitors and a regulator. Number 2) needs more components
In my application, does it matter if I would connect solar cells in series to get voltage or parallel to get current?
I have a number of other questions aswell, but I figured I could see what you say regarding this first
Thanx!