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i m doing a project on solar tracking system using mppt and using pic16F877A.we had doubt that how many LDR (light dependent resistor)are supposed to be used and where it has to be placed according to intensity of sun light please give some ideas.
i think it should be 4 LDRs 2 each in elevation and azimuth
control should operate the motor or whatever mechanism is, so as both thr LDR in one direction heve equal intensity
LDR have to be covered in short black tubes and need to have a delay to allow for passing clouds
i think it should be 4 LDRs 2 each in elevation and azimuth
control should operate the motor or whatever mechanism is, so as both thr LDR in one direction heve equal intensity
LDR have to be covered in short black tubes and need to have a delay to allow for passing clouds
Hi ,
You are right you will need 4 LDRs. passing clouds does not affect it the tubes should be mounted close by in an angle as shown in fig, I have made an analog tracker in 1987 succesfully with a single chip LM324 as my study project.
regards ani
i m doing a project on solar tracking system using mppt and using pic16F877A.we had doubt that how many LDR (light dependent resistor)are supposed to be used and where it has to be placed according to intensity of sun light please give some ideas.
Hi sreeja,
In my project i used the strategy to compare light falling on the two ldrs and drive the motor till both are equal. and there should be another ldr to sense sunlight and cut off the motor supply when sunlight falls below a particular level.
regards ani
I am doing the same project..
I got some problem: The LDR under shade and the LDR under direct sunlight has the same reading.. The resistant of both LDRs are very low when I test them outside.
Currently it only work when demo with a flash light indoors.
- - - Updated - - -
PS: The resistor I used as Voltage divider is 47k ohm.
It sounds like it's simply too bright for the LDR and you are off it's 'linear' brightness/resistance curve.
Your options are:
1. reduce the series resistors but this will increase current consumption and heating in the LDR which will make the reading less reliable.
2. shade the LDRs to prevent as much light falling on them. A trick I've used with outdoor webcams is to place a 'reactolite' photochromic lens from sunglasses over the camera lens to increase the range of light it can cope with.
3. possibly use a different method of detecting the light direction: place four LDRs as close together as possible in a square arrangement and cover them at a distance of a few cm away with a black shield. In the shield put one small hole directly over the center of the square. Now as the light angle changes the beam of light falling through the hole will fall unevenly on the LDRs to allow you to determine the movement needed to centralize it. The advantage of this method is you can adjust the hole size to cater for different light levels.
It sounds like it's simply too bright for the LDR and you are off it's 'linear' brightness/resistance curve.
Your options are:
1. reduce the series resistors but this will increase current consumption and heating in the LDR which will make the reading less reliable.
2. shade the LDRs to prevent as much light falling on them. A trick I've used with outdoor webcams is to place a 'reactolite' photochromic lens from sunglasses over the camera lens to increase the range of light it can cope with.
3. possibly use a different method of detecting the light direction: place four LDRs as close together as possible in a square arrangement and cover them at a distance of a few cm away with a black shield. In the shield put one small hole directly over the center of the square. Now as the light angle changes the beam of light falling through the hole will fall unevenly on the LDRs to allow you to determine the movement needed to centralize it. The advantage of this method is you can adjust the hole size to cater for different light levels.
The light passing through the hole will disperse into a cone shape so by choosing the correct distance between the hole and the LDRs it should be possible to prevent it completely leaving the square. The objective is for the cone of light to fall equally on all four sensors, in other words with the axis of the cone in the center of the square when exactly on target. Please note that the light crosses over as it goes through the hole so the directions are reversed compared to the methods which point the LDR toward the Sun.
I am doing the same project..
I got some problem: The LDR under shade and the LDR under direct sunlight has the same reading.. The resistant of both LDRs are very low when I test them outside.
Currently it only work when demo with a flash light indoors.
- - - Updated - - -
PS: The resistor I used as Voltage divider is 47k ohm.
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