Help: 4.5V 1/4W Solar Cell 2"x1" Size Required for Robotic Bugs

Have you calculated if the incident solar power can support that wattage?

Tornado;

Yes, this is actually in some kind of flood light so light source is strong enough and is solar spectrum equivalent. In actual solar light current will fall but charger should take care of that part. Charger is fill bucket and dump charge type so even if power drops to 10mA source, it can keep working well. I thought about that. I have maximum surface area 2"x2" top and on sides but I will like to keep some for upward communication as well. May be I can mount solar cells in V shape or pyramid shape or on four walls then they can be full 2"x1" four numbers. I have some communication on all four walls as well so that each Robot can talk to its immediate neighbours.

I can mount up to five numbers of 2"x1" solar cells.

1.25W solar power on equator for 2"x1" surface.

1.25W solar power, at an efficiency of 0.2 gives us about 0.25W. Even less, for some PV cells. The cells that I used (6x4 in) gave me only .5V, so you need a combination of cells to get your voltage, to use a booster, or both.

indel;

Perhaps you have selected a wrong solar cell / module or you may be over loading it.

Even those solar cells used in calculators give 1.7V to 2.8V. Just $1 calculator may have one fitted inside. I have just broken one old calculator and found one Panasonic Solar Cell which I have tested for unloaded 2.8V in sun light and is perhaps for 1.8V actual use and its size is 1cmx4cm. This was designed for indoor use and not even for sun light use.

I am making V-I tracer and power optimizer circuit for testing solar cells and photo voltaic solar cell modules. It will be used for testing solar cells that have as small as 1uA 500mV output to 20A 500V output. I may get small fund from University for making solar cell tester for educational / research purpose and that may fund my work. I will then use it for testing a variety of solar cells and modules. It is good to test individual solar cell as a bad solar cell in parallel or series can do lot wrong to the output power.

In India we get bad solar cells of 15% efficiency and I am looking for 30% efficiency and about 300W/m sq. area. What we get is only half of that power from many manufacturers.

Have you tried searching the internet? I got 4,620 results just typing in your request. There are several listed on eBay. Otherwise you might contact manufactures who can fit your dimensions and power requirements

di95401;

There are some local solar cell manufacturers but their solar cells are less efficient. I just want to see if I can find some bare solar cells of high efficiency something that are used in space missions.

I will need 5000 x 5 = 25000 solar cells of size about 2 sq. inches or about 25 sq. cm. area in shape 2"x1".

Something like this

Highest Efficiency solar cells

I kinda figured you done your homework That's a pretty impressive link you posted. Have you tried to contact them? It's a substantial order your looking to fill.

Good Luck with your endeavor!

dj

di95401;

Yes, I have written to them but it looks like a research work. Let them reply. I am also considering 30% efficiency solar cells or even 25% efficiency versions but 45% efficiency is very impressive for sure.

I am also planning good power management to reduce wastage and use the power under planned manner to let the Robot survive but remain sleepy when under low power. I am planning to separate the critical information collection part to keep working all the time and wake up type actions for movements and other actions.

I am going to place few sensors on the Robot for survey purpose. Sensors are of size 10mmx10mmx10mm and can fit inside. I have Gamma radiation sensors and few chemical sensors and few environmental sensors. They have primitive eyes to just sense walls and other objects so no camera yet.

You're not going to get anywhere near that efficiency without concentrating lenses....and that means high heat...I'm assuming you just want 1 solar power cell type....?...

SolarEagle;

No lens in this design. Yes I need 45% efficiency if I have to use 1 solar cell. Only 10% efficiency if I use 5 solar cells. I think that is all feasible. As solar cells commercially available for 25% efficiency for 1eV to 3eV energy, I just may need 4 such solar cells to get desired 1.25W/h X 8 hours = 10W power. I think it is pretty good for the tiny Robot. All I need is about 6W power to be added to the Batteries in day time and also same amount to be available for running the Robot. In remaining period Robot to working on the stored 4W power under reduced power mode.

SolarEagle;

Good information.

Yes, these sound pretty good at 28% efficiency. I also like 15C to 75C operating temperature range that is what I am going to face in open sun and hot and cold winds. 17mA/sq. cm is not at all bad as I have 25 sq. cm top surface so even half of that can give as good as 200mA at 2.2V. Two in series I can get 4.4V 100mA which is excellent.

We pay for what we want.

I might be totally out here but for that kind of grade of cell you might be looking at $100 to over $500 per cell. Now x 5000 x 2 = $1 to 5 million, you might be able to get a substantial bulk discount but that still looks pretty expensive to me. A little tip is that anything that says 'Orbit Certified' is going to be 10 to 100 times more expensive. : )

(Was recently pricing components for cube sats.) http://gomspace.com/index.php?p=products-p110

Robert Lucien;

Thanks for information. Space solar cells differ considerably as they undergo high temperature changes, work in vacuum where conduction cooling is impossible, stress levels are very high. These at Euro 2000 for 2W on earth is not something I am looking for right now.