Self-cleaning solar panel in a desert

[sam_smk]

I am making a self cooling & self cleaning solar. I have already finished the cooling part by attaching fins from the back of the solar.

Now, I am going to clean the solar using compressed air system. I am going to attach a 35 in tube from one of the sides of the solar and has a diameter of approx 5 mm.

I am trying to figure out which air motor should I buy to cover the whole solar and how many holes should I be making in the pipe(so the air would reach from one side to the other).

Which equations do you guys think I should be using?

Here is the solar we are using if you are interested
http://www.harborfreight.com/15-watt-12-volt-solar-panel-96418.html

( We choose an air motor because the solar is going to be in a dry area. So we are only worried about dirt)

 

[berkeman]

I am making a self cooling & self cleaning solar. I have already finished the cooling part by attaching fins from the back of the solar.

Now, I am going to clean the solar using compressed air system. I am going to attach a 35 in tube from one of the sides of the solar and has a diameter of approx 5 mm.

I am trying to figure out which air motor should I buy to cover the whole solar and how many holes should I be making in the pipe(so the air would reach from one side to the other).

Which equations do you guys think I should be using?

Here is the solar we are using if you are interested
http://www.harborfreight.com/15-watt-12-volt-solar-panel-96418.html

( We choose an air motor because the solar is going to be in a dry area. So we are only worried about dirt)

Since this is a schoolwork project, I've moved your thread to the schoolwork forums.

I'm not sure that trying to use airflow to clean the solar panel will be very effective. I would think some kind of a brushing mechanism would work much better. What other cleaning options have you explored? What is the surface material of the solar panel? How hard is it? Would it resist scratching if a soft brush mechanism were used for the cleaning? How often will humans be in contact with the solar panel to do a better cleaning job?

 

[sam_smk]

Since this is a schoolwork project, I've moved your thread to the schoolwork forums.

I'm not sure that trying to use airflow to clean the solar panel will be very effective. I would think some kind of a brushing mechanism would work much better. What other cleaning options have you explored? What is the surface material of the solar panel? How hard is it? Would it resist scratching if a soft brush mechanism were used for the cleaning? How often will humans be in contact with the solar panel to do a better cleaning job?

"brushing mechanism" That was our first design using a stepper motor. However since the solar is going to be installed in a very dry area (No rain) a compressed air system seems to be more effective. We only want to blow the dirt out of the solar panel surface.

Brushing mechanism would require us to use water and that's not possible in a dry area.

 

[berkeman]

"brushing mechanism" That was our first design using a stepper motor. However since the solar is going to be installed in a very dry area (No rain) a compressed air system seems to be more effective. We only want to blow the dirt out of the solar panel surface.

Brushing mechanism would require us to use water and that's not possible in a dry area.

I was thinking more of a dry, soft brush, as long as the solar panel first surface is hard enough not to get scratched by the dirt and brush. Have you been able to characterize what the dirt will look like? I picture what the dirt on parked cars looks like after a long time with no rain...

 

[sam_smk]

I was thinking more of a dry, soft brush, as long as the solar panel first surface is hard enough not to get scratched by the dirt and brush. Have you been able to characterize what the dirt will look like? I picture what the dirt on parked cars looks like after a long time with no rain...

The solar will be placed in the desert. Anyways, it's too late to try and do something else we have to work on this one.

 

[gneill]

Blowing dry air across the surface may deposit a static charge that will attract more dust than you get rid of...

 

[David Lewis]

If you turn the panel upside down at night, it will accumulate less dirt. And the air blast will remove more dirt if you clean it then too.

 

[berkeman]

If you turn the panel upside down at night, it will accumulate less dirt.

Excellent point.

@sam_smk -- Are you going to track the sun in 1 axis or 2?

 

[NascentOxygen]

since the solar is going to be installed in a very dry area (No rain)

No rain, maybe, but what about overnight dew condensing on the panel? Deserts can get cold once the sun goes down—and there is no cloud cover.

 

[sam_smk]

Thank you all for your input. I just realized how little I know about weather.

However, I need help calculating the motor power I need for the air to cover the whole solar and how many holes I need for the tube

"I am going to attach a 35 in tube from one of the sides of the solar and has a diameter of approx 5 mm."

The solar dimensions :-

Length 36 in.
Width 12in

 

[sam_smk]

Excellent point.

@sam_smk -- Are you going to track the sun in 1 axis or 2?

I am not sure we have the power to do that

 

[gneill]

I am not sure we have the power to do that

What's your power budget for all the accessories? Compressed air isn't "cheap".

 

[sam_smk]

What's your power budget for all the accessories? Compressed air isn't "cheap".

I understand it's expensive. We are not going to buy it, I am simply going to draw it using Solidworks next to the solar panel. I am asking this question because if I choose one of the motors my professor will ask me "what type of calculations have you came up with, to choose this particular motor?"

Of course the motor can not be the most expensive one in the market, but be sufficient enough to cover the whole solar. Meaning the air has to reach from the tube to the other side.

So do you happen to know an equation I can use to calculate it? The velocity of the air coming out of the holes on the tube has to be powerful enough to reach to the other side of the solar

 

[gneill]

I understand it's expensive. We are not going to buy it, I am simply going to draw it using Solidworks next to the solar panel. I am asking this question because if I choose one of the motors my professor will ask me "what type of calculations have you came up with, to choose this particular motor?"

Sorry, you mistook my meaning (my fault, really). By "not cheap" I meant in terms of energy. You must have some idea of the amount of power you have available to run any support equipment. Will the solar panel be the only source of energy?

Of course the motor can not be the most expensive one in the market, but be sufficient enough to cover the whole solar. Meaning the air has to reach from the tube to the other side.

So do you happen to know an equation I can use to calculate it? The velocity of the air coming out of the holes on the tube has to be powerful enough to reach to the other side of the solar

Sorry, I don't have that information. Not really my area. If I were to guess I'd say that you're looking at volume over velocity, since you'll want to set up a flow of air that isn't immediately damped and dissipated when it hits still air. What comes to mind is something like a vacuum cleaner on "blow" feeding your air ports. Alternatively you could compress and collect air over a long time period with a small pump and release it periodically in a single burst.

 

[sam_smk]

Sorry, you mistook my meaning (my fault, really). By "not cheap" I meant in terms of energy. You must have some idea of the amount of power you have available to run any support equipment. Will the solar panel be the only source of energy?

We are thinking about an air tank that should be filled up using the solar panel

 

[berkeman]

I am not sure we have the power to do that

We are thinking about an air tank that should be filled up using the solar panel

It sounds like you need to do some more calculations then. Solar tracking requires very little energy, especially for a small panel like the one in your project. And you can do the calculations to figure out how much extra energy you gain versus a fixed solar panel.

Running a compressor will take orders of magnitude more energy than running a simple brush across the panel once per day IMO.

 

[sam_smk]

It sounds like you need to do some more calculations then. Solar tracking requires very little energy, especially for a small panel like the one in your project. And you can do the calculations to figure out how much extra energy you gain versus a fixed solar panel.

Running a compressor will take orders of magnitude more energy than running a simple brush across the panel once per day IMO.

You mean the Solar panel will not produce enough energy to power the the compressor?

 

[gneill]

Perhaps consider a scrolling cover? A thin membrane that is unspooled and re-spooled (like a roll of Saran-Wrap^(TM)). It could creep along continuously at a very slow pace, or be triggered to step one "frame" when the panel output drops below a threshold. The possibilities would depend upon the capabilities of any controller hardware and software that is being planned.

What are the expected maintenance schedules? How long will the system have to operate unattended?

 

[berkeman]

BTW, in engineering, you sometimes need to re-think your approach when you get farther into a project and do more detailed calculations and feasibility studies. If you can show that a better design would be to use X and Y instead of your original proposal, that's the way real world engineering works.

You mean the Solar panel will not produce enough energy to power the the compressor?

Those calculations are for you to do. It is your schoolwork project, after all.

 

[sam_smk]

BTW, in engineering, you sometimes need to re-think your approach when you get farther into a project and do more detailed calculations and feasibility studies. If you can show that a better design would be to use X and Y instead of your original proposal, that's the way real world engineering works.

Those calculations are for you to do. It is your schoolwork project, after all.

I'm going to do it of course but I am not sure what equation I should be using

I need a name for an equation so I can look it up and plug in the numbers

 

[berkeman]

I'm going to do it of course but I am not sure what equation I should be using

I need a name for an equation so I can look it up and plug in the numbers

Engineering is not usually just looking up an equation and plugging in numbers. Look up the specifications on small compressors. What pressures do small compressors pump to? What energy is involved in compressing that volume of air to that pressure?

And by comparison, how much energy does it take for a stepper motor to transit a cleaning brush across your solar panel once per day? How much (tiny) amount of energy does it take for two other stepper motors to pivot your panel to stay tracking the sun?

 

[NascentOxygen]

If you arranged for an "empty" gas cylinder to be open to the air at night then tightly sealed at daybreak the sun's heat would then raise its pressure and you could trigger its release as a burst of pressurised air around midday^✲. ... Repeat daily. Is one burst each day enough to dislodge dust/sand?

Make sure you double-check those pressure calculations...

^✲ or just when the pressure reaches a preset value will be safer

 

[berkeman]

Make sure you double-check those pressure calculations...

PV=nRT be sure to use Kelvin...

 

[NascentOxygen]

PV=nRT be sure to use Kelvin...

Absolutely!

 

[sophiecentaur]

I really like the idea of as endless scrolling clear cover. It could pass under a cleaning pad and brush. The motor would actuate when / if other demands were low ( batteries charged etc.) so the energy would be free. A dust detector, based on scattering, could govern how long the cleaning cycle lasts. Minimal run time would minimise scratching.