Daniel_M

Hi all,

I am planning on solar powering an aircraft that I have designed, and I'd like to know how I calculate the specifications for the solar panels. What I'd like to know is how to calculate the total electrical energy that my rc system draws- and so find out how many Amps and what Voltage the solar panels will have to produce.

Anyone, please tell me how to find this out- pelase write down the steps or point to a link.

I deeply aprpeciate it,

Daniel.

Scar

My Feedback: (3)

Let me guess. This is a troll, right?

Daniel_M

Hi Scar,

Troll? What does that word mean?

Best Regards,
Daniel.

PS. I will be using an ESC which has:

Current- 10A
Weight- 14 grams
Battery (that is if I were using a battery)- 2 to 3 LiPo

I will also be using a motor which has:

Power-80W
Weight- 28 grams
Max Current- 9A
Efficiency- 79,7 percent
Battery (again that is if I were using a battery)- 2 to 3 LiPo
Kv- 1200
Resistance- 0,243 Ohms

Now I am no eletrical genius so some of these values mean almost nothing to me. If anyone knows of a calculator- or just knows the steps one can just follow without needing to understand all this... please share )

Deeply appreciated,

Daniel.

Lnewqban

Hi Daniel,

As far as I know, it has been done before at experimental levels.

The main problem is the cost of the solar cells, plus their weight and the poor electrical output compared to the needs of a motor for high performance flights.
The model itself should be very light and kind of slow flyer.

I believe you could get more responses if posting at:

http://www.rcuniverse.com/forum/forumid_106/tt.htm

Best regards!

ChuckW

I would contact a solar panel manufacture. They can likely recommend something based on your battery, power requirements, etc.

I imagine you are gonna need a really light airplane with a huge wing to accommodate those panels and make it flyable on as little power as possible.

Daniel_M

Thank you for all your responses, I appreciate it. Yes, I thought that the plane will have to be a sailplane with a ridiculously low wing laoding in order to be entirely solar powered. The airplane I am going to convert to solar power is my ownd esign and it is a low-wing trainer with a minimal speed of 17.6 ft/s and a weight of 0.882 lbs plus a wing area of 1.5 ft^2.

I am now thinking of using solar power to only power the radio equipment- servos and reciver. The motor will be seprately powered by a battery. How does that sound?

Best Regards,
Daniel.

Lnewqban

I believe yours is a good idea.
The economy and power of new Lipo batteries is impossible to bit; however, your idea is a very interesting exercise.

I just run a Google search for solar power model airplane and got back many interesting articles about solar energy used for model and full scale airplanes in Switzerland and other countries.
Check them out![sm=thumbs_up.gif]

redfox435cat

are you telling us you single handedly designed a perpetual motion machine, or are you asking if a perpetually motion machine can be designed by a basement modeler? This has been a dream for centuries with millions and million of dollars, more like billions dumped into it so if you can do it please share with the world, your Pulitzer prize is waiting. I've seen some trial runs and it is doable but I know I couldn't afford it, good luck to ya

I will say that some huge leaps in the design of solar panels just this last year may make it possible to greatly increase flight times by doing what you suggest. It only took about 300 million to develop.

Goolge nano solar. These guys came up with a method of printing solar panels. These things are light and flexible and could theoretically incorporate them in the top of a wing, they are talking about making roof shingle and car roofs out of them but won't be available to the public for years.

jester_s1

Daniel- In fishing, trolling is driving your boat slowly while dragging some bait behind it just to see what will come up and bite it. In internet slang, a troll is a post that was only made to get a reaction from people. It's usually something ridiculous or highly controversial, and the troller gets to sit back and watch people argue.

ampeater

My Feedback: (1)

IIRC, solar flux hitting the earth ranges from 0 to a max of about 1400 Watts/sq-m. Solar cells are about 15% efficient, so the max you'd get from a sq meter panel is about 210 watts. But thats with the sun directly overhead and the panel directly facing it. Average, you might get about 1/2 of that, or about 100 watts per sq-m, so that's about the size panel you'd need. Normally, you'd still run off of a battery, but just use a solar panel to recharge it and extend your flight time.

Daniel_M

Question: When I install multiple solar panels, will their electrical output be summed up into a total... in other words, will their currents be added up- so that if one panel has a current of 100 Amps, then two panels will have a current of 200 Amps? Will the same go for the Voltage?

I am asking this because the servos have anrunning current of 150 Amps, and the Powerfilm rc7.2-75 R/C aircraft solar panels I will be using each have put out a current of 100 Amps. So, if I utilise 2 such panels, they will put out a current sufficient enough to drive my servos??

Any answers deeply appreciated,
Daniel.

redfox435cat

how big a plane you talking about 1 sqr meter might yeild 2 amps in perfect conditions. but yes it as one solid unit. you wire them in series for voltage parallel for current

skeeter_ca

Are you sure it's amps and not milliamps? I've never heard of a normal solar panel putting out 100 amps or a servo using 150 amps.

skeeter

cowana

Put them in parallel: add up the currents.
Put them in series: add up the voltages.

Series: -oo-

Parallel: {8}

Andrew

draftman1

you could use the battery to get the plane up then shut it off for really slow flying, maybe?

TFF

Back in the 80's RCM magazine and the AMA magazine had how to articles on putting solar panels in glider wings to power the radios; you might be able to get a reprint. Both had some kind of buffer circuit.

redfox435cat

, are you sure were not taking milliamps

that's what I was thinking. I have a solar array on my house, 50 sq feet yields 5 amps, If I were to build a new one today I get about 8 amps out of the same area, this is why this is a laughable concept the guys is bringing up. The best he could do is have a thermal glider prolong the power requirement for the servos which is what was done with the plane in question, technically it was still solar power because the wind currents they were riding were generated by solar energy, I have had 2 flight over 3 hours with a thermal glider, this was under perfect conditions on a dry lake bed chasing the model laying the back of a truck. Also I've flown over 6 hours several times slope souring and nearly lost the model twice because the battery for the servos almost quit. Hae a very light solar cell on them might have helped

jimmyjames213

My Feedback: (2)

i was thinking about doing this w/ a dynaflight butteryfly, havnt got around to it yet.
here are my calculations
a 6x3 solar cell produces .55v at 3.6 amps
so 20 cells will give you 11v at 3.6 amps or 11*3.6= 39.6 watts
6x3*20 is 360 sq inches. so if you have a nice big wing, the dynaflight has 916 sq in.
lets say you can put 40 cells on it (i have no idea if it could fit or not due to the curvature of the wing), giving you about 80 watts at full sunlight,
here are the cells http://cgi.ebay.com/50-3x6-not-broke...3A1%7C294%3A50
i asked the rep and they said that they would weigh about a pound for 40 cells.

so in my opinion it would fly w/ 40 solar cells
have fun

Lnewqban

Check this out:

http://www10.mcadcafe.com/nbc/articl...ction=CorpNews

Daniel_M

jimmyjames213:
Thanks for all of your answers guys, and yes the servos use 150 MILLIamps, not amps
I will think about the dynaflight butterfly plane- and thank you for the link to the cells, I appreciate it a lot James!

Draftman1:

Great idea! I think that I might do just that! Now here is the problem that if anyone can, please answer (I'm thinking about it too):

1) How do I kill theenginein-flight, hence stopping draining the battery power?
2) How do I wire the airplane so that the battery ONLY powers the motor while the solar cells provide energy for the servos and receiver?
3) How do I wire everything so that while the battery is shut off, the solar cells charge it with any excess energy that they produce?

So, here is the setup for the aircraft:

Solar panels:

- In charge of powering the 4 servos and the receiver
- Charge the LiPo battery with any excess energy that they produce

LiPo battery:

-In charge of powering the ESC/Engine
- Cannot be allwer to power the servos and receiver.

Again, how to I hook up eveyrthing so that the battery is only for the engine, solar panels charge the battery and pwoer the servos/receiver- and everything uses the same receiver???

Anyone, please, a rough drawing as an attachment to your post would be very very VERY deeply appreciated.

Answers deeply appreciated,
Daniel.

Daniel_M

lnewqban:

Very interesting article!

Best Regards,
Daniel.

iron eagel

Daniel,
You may want to add a small backup battery for the receiver/servos, just in case you have a dropout of output from the solar cells so you can maintain radio control. Keep in mind just the shadow of a cloud or aircraft/bird could cause the output of the solar cells to drop out momentarily. Such a momentary dropout would cause you to lose control of the aircraft, not a good thing!
You also may be able to use a large capacitor to store output of the cells in the event of a dropout. If you use a battery for backup I would use a nicad rather than a li-pol due to the circuitry that you would have to use in the case of a li-pol to prevent charging the battery with the solar cells...
To isolate the engine power and esc from the receiver power circuit all you need do is cut the +5v lead from the esc to the receiver, you may want to use a short extension and cut that lead on the extension and leave the esc wires intact.
What type if wattage are you planning in using for the aircraft power?