Improving Efficiency Using a Lens

[3v0]

There may be more the one way to track the sun.
One method does not require knowing the motor position. A pair of CDS or photransistors with a divider between them as seen in many of the plans is used to determine motor direction and when to stop. A limit switch at the end of travel in each direction for the obvious reason.

Most any motor is going to be to fast exectpt a gear motor of the right RPM.
Check the surplus places to see if you can get what you need at the righ price and not have to futz with the gearing. The surplus places may also have gearboxes without motors that you could hook a drill to and end up with a useable RPM. Maybe even have one drill drive the gearbox from a second canablized drill.

If you want a dirt cheap high torque DC motor go to a local bargain or thrift store and pick up a couple of the cheapest battery powered drills you can find, they contain decent sized brushed motors and all the gearing required to produce heavy torque. You'll need to figure out how to detect position though, if you're just using a couple of rotating gimbals for the panel it could be as simple as mounting a potentiometer to the drive axis. Using a H-bridge rated to drive the motors and two ADC pins on a micro controller you'll get two axis rotation control. Then the hard part is to calibrate it and program the sun following routines.

Also, you'll want to find as detailed a data sheet on your solar panel as you can, the brightness of direct sunlight can be easily calculated and you can determine how many reflectors you can safely use for your panel. Even just two mirrors should greatly increase your power output without excessive heating.

 

[bryan1]

Hi Moneer,
For a motor try getting hold of say a 12 volt wiper motor off a car. Awhile ago I did a utube video on the testing of a 24 volt wiper motor YouTube - Wiper motor test

This video shows the current draw and voltage and when I tried to stop the shaft the current didnt rise at all. The car wiper motor is basically a DC motor coupled up to a worm drive, now hook the output thru a reduction system of bike sprockets and chain and with the extra torque gained you'll find it will drive a small pv tracker easily and the reduction will also serve as stablization against wind. I made my own up to suit a 350 watt array using 2 175 watt 24 volt panels but showing a pic of them to you won't serve the purpose of your learning.

Now using this system you can makea simple circuit to either go thru 1 axis travel a day or use some led,cds etc tracking system.

Hopefully I've given you enough to go on with.....

Regards Bryan

 

[rjvh]

i used in the past motors with a worm wheel but that whas for a colector panel (hotwater) so the weight was a bit more (about 35 Kg of moving weight)

I did find the motors in a dump shop and i believed they where from a copier machine

Robert-Jan

 

[Moneer81]

hey guys,

Thanks for all the informative replies. I created a new thread for my solar tracker project. Please check it and let me know if you have any feedback. Here it is:

Thanks

 

[tinkerunique]

a fresnel lens was mentioned - that is a marine (boat) lens - That would be great used to make steam heat, or to start fires. A decent-to-good solar cell should not need anything else. Instead of spending $$ on a lens, spend the same $ on a better solar cell. IF you want to make heat, then use a lens.

 

[Ross Craney]

i think that a lens doesn't work to improve efficiency

as you consentrate more solar energy it is manly in the form of heat and one of the things that Photovoltiac cells make less efficient is heat


for heating up water in solar colectors it does work and i made one proto type in small dimentions to messure the differance with if you don't colect more sun (enlarging the sqr meter catchment area)

i only used mirrors no lenses

Robert-Jan

My understanding exactly. More heat will decrease its efficiency. Have a look at the temperature specs of you panel - you will probably cook it & kill it.

 

[Blatman Bond]

Hey guys, take a look at CPV it is incredible. 43% of efficiency.

 

[Thunderchild]

and where are we looking ?

 

[Blatman Bond]

I'm interesting to buy one, but I don't know where to buy it.
here some link for info:
https://www.electro-tech-online.com/custompdfs/2009/08/EMKR_AeA_11_03_2008.pdf
http://www.greenandgoldenergy.com.au/images/SunCubeMark5CloseSmall.jpg
http://thefraserdomain.typepad.com/energy/images/1m2sunball.jpg

 

[Blatman Bond]

Unlike regular PV, CPV has more stability and performance at noon (not decreased by overheat temp).
Seems it will beat solar stirling engine.

more links:
**broken link removed**
looks like, the pioneer:
**broken link removed**

 

[smanches]

A lens does nothing to efficiency what-so-ever. Effeciency of a solar cell is based on it's area vs the power out. When applying a lens, you are basically increasing it's area to the size of the lens itself. This is the same as adding mirrors to reflect light onto the cells.

Since you are now making the light go through a second medium before getting to the cell, you are actually losing efficiency. The only way to increase the efficiency of a cell is to redesign it.

 

[Mike_2545]

You could monitor the temperature of the panels and spray the backsides with water to cool them when they get hot, that would increase efficiency.