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One simple mirror it can offer 40% more performance at the solar cell.
Kiriakos GR:
I do not know how many are aware that a simple mirror it can offer 40% more performance at the solar cell,
when it is placed flat down and in front of solar cell it self.
Beware I am not talking about a complete panel !!
What I did was to add one small scale solar cell on a multimeter and by adding one mirror flat and in front of them I got 40% more current from it.
I am not saying 40% more voltage as its one cell haves it own max voltage output.
What probably happened in my case is that the mirror managed to double the light in a way, and the cell received the max solar energy for it size.
In the bellow picture imagine instead of wood this meter to be placed on a mirror !! ( The magic gets in to play after that) ;)
Complete link of my finished project if you care to see it.
http://www.ittsb.eu/forum/index.php?topic=91.0
Every comment about this trick that causes so much extra gain is welcome.
SeanB:
More light means more current up to a point where the cell saturates. If you use a parabolic mirrir to focus on a cell you can get a lot out of a cell, provided you can keep it cool so it has a higher open circuit voltage.
Kiriakos GR:
--- Quote from: SeanB on December 02, 2012, 12:40:12 AM --- you can keep it cool so it has a higher open circuit voltage.
--- End quote ---
My first thought after watching this effect was some videos about making an solar oven. ;D
In my test, the multimeter inner temperature stabilize to 32C and the solar cell temperature raised close to 42C.
The special automotive dual side tape that I have use, has some serious thickness which block the heat transfer.
The environmental temperature this day was up to 25C.
--- Quote from: SeanB on December 02, 2012, 12:40:12 AM ---
up to a point where the cell saturates.
--- End quote ---
Yes I think that this is the point that I did reached, by feeding the cell with light from any vertical angle.
In my test after adding the mirror the actual horizontal positioning at facing the sun become less important.
An better description could be, that the horizontal degrees range, about getting the most of it, become wider.
The sum of my thoughts leads me to believe that every solar cell with out active positioning it can benefit allot by the mirror.
SeanB:
Using a reflector means either building in basic tracking to keep the reflection on the cell, or using a parabolic or other shape such that there is a large portion of the day that a reflection is on the cell in addition to the sun direct. If going to high power you would probably have to use a water cooling system on the cells. A plus is that you can use high efficiency cells and fewer of them, and the power gain in the conversion will probably offset the cost and complexity of the water system and the tracking system.
MJLorton:
--- Quote from: Kiriakos GR on December 01, 2012, 03:27:03 PM ---I do not know how many are aware that a simple mirror it can offer 40% more performance at the solar cell,
when it is placed flat down and in front of solar cell it self.
Beware I am not talking about a complete panel !!
What I did was to add one small scale solar cell on a multimeter and by adding one mirror flat and in front of them I got 40% more current from it.
I am not saying 40% more voltage as its one cell haves it own max voltage output.
What probably happened in my case is that the mirror managed to double the light in a way, and the cell received the max solar energy for it size.
In the bellow picture imagine instead of wood this meter to be placed on a mirror !! ( The magic gets in to play after that) ;)
Complete link of my finished project if you care to see it.
http://www.ittsb.eu/forum/index.php?topic=91.0
Every comment about this trick that causes so much extra gain is welcome.
--- End quote ---
Great to see the end result and all your testing you posted Kiriakos. I've had similar issues using diodes with small solar cells charging AA batteries. The losses / voltage drop was an issue and in many of my projects I just left out the diode. There's obviously the loss / leakage back through the solar cell to consider but in many cases this has not been a problem i.e. losses including a diode vs not.
I have an LED sensor light (scary old YT video...goto 10:47 - http://www.youtube.com/watch?v=WWqiiXrgC-E) that I originally setup in the States...now used here in South Africa daily. It's been working for 3 years with no problem...original Duracell rechargeable batteries...which I thought would have been "cooked" by now.
The thoughts on using a mirror to enhance performance are interesting. Good input from Sean.
I still want to play with the cooling side of larger PV panels. I can certainly see how the performance of our array (2250 watt) is affected on a "normal" hot summer day down here in Cape Town. On a clear cool day at the peak (12-1pm) it will produce 2300 + Watts...I've seen it sustain 2500 watts at times and even hit 3000 watts for short durations. On a clear hot summer day it will only sustain 1700-1800 watts at midday.
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