I am attempting to use thin, flexible solar panels to charge a battery on a plane (RC) for a school project. After fully charged, I will begin flying the plane, and the panels will hopefully extend the flight time by charging during flight. The battery is a 2100mAh, 11.1V LiPo. The solar panels will be placed on the wing, which is 7.5" x 31". I may be able to fit a couple of small panels on the tail as well. The problem I have is finding appropriately sized, lightweight panels that can produce at least 600mA of current. A few of my options are:
1.) 6.0V, 100mA, 4.5×5.9"
2.) 7.2V, 100mA, 3.0×10.0"
3.) 7.2V, 200mA, 5.9×10"
4.) 4.80V, 50mA, 3.0×3.7"
5.) 4.20V, 22mA, 1.5x.3"
I'll need to wire two panels in series to get the necessary voltage, but then I'd need multiple sets of these in parallel to get a worthwhile current going. Would it be possible to wire the large 7.2V, 200mA panel in series with a small 4.80V, 50mA panel? Would that result in 12V and 200mA? If not, are there any better configurations with my options? Otherwise, it looks like I could only get 200-300mA with the larger panels.
Electronic – In-Flight LiPo Charging via Solar Cells
currentliposeriessolar cell
Related Solutions
When connected in series, the maximum current is as high as that of the weakest link, so yes, 4A. The voltage will be the sum of all cells, so 1V.
When connected in parallel, the maximum current is the sum of all cells, 12A in this case. If you do this, you should only connect cells of the same voltage in parallel, otherwise you get unwanted current flows.
Best Answer
You could wire the two dissimilar panels together. The max current would be 50mA though, but would be 12v (0.6W).
A key to good solar power output is having matched panels, otherwise you are making an already inefficient conversion even more inefficient since the panels won't be operating at their maximum power point. Maximum Power Point Tracking
That being said, your 1.44W (7.2V @ .2A) panel will only output that at its maximum power point, charging a 2.1Ah battery with full power from the panel would take 12.6 hours to charge it. It would be on the ground well before any useful solar power has charged the battery. Not to mention you just added weight, increased drag, and wasted time.
There is an optimal size for adding solar to have any useful effects. Check out Sky Sailor He is the originator. His site has matlab models/scripts to use that calculate at what point you could be powered entirely by solar.