I`m a student form italy and last year (senior year) me and my best friend made 2.3 meters (something like 2.7 yard) solar powered aircraft, of course handled by ardupilot!
It has been more a journey than a project, making it we learnt -and still are learning- more than we ever did in some of our diy projects.
The planes actually flyes good, with an overall consumption of bout 28 watts/h, and an onboard solar production ranging from 33 watts at noon of an awesome summer day to 23/25 watts of you average summer day.
Still, we have a 33 watts/h LiPo on board so we can have that extra power for take of and give the plane that little 3/4 watt/h help it needs to fly :-)
Attached there is a picture of the beast, next 3 weeks are gonna be busy as hell in college so no tiem to translate and post the two technical relations we made about it (one include xflr5 simulation of the Thing), which were necessarily written in Italian because we incidentally used this aircraft as our "senior year personal project" too, but at the beginning of august we will feed you with all the telemetry data and so on you may want to see.
EDIT: PHOTOS HERE!!!!! ==> http://img52.imageshack.us/slideshow/webplayer.php?id=1001042k.jpg
Shaded parts of the cell is pretty sad because for half of the time (we we are not flying with the sun in fornt or on the back) a little portion of each cell is not being used, still, that part is relatively small when the sun is high in the sky and alto that kind of cell when not illuminated is like an open circuit so the "shadowed" part of the cell is just a "dead weight" but is not consuming power ;)
I think you need to research the consequences of shading a solar cell. It's not as insignificant as "dead weight".
Thankyou for the links,
we know that shading a single cell in a series "kills" the whole thing but this is not something that happens on our plane, where all the cells are exposed almost always in the same way, so since the power of every cell is reduced by teh same amount we arent wasting energy adn we can consider dead wheight the shaded part, we ground tested this ;)
Hi guys! We are working on a big public archive with a lot of useful data about our aircraft, we are now working on finals exams of first semester in our engineering college (Politecnico Di Milano, a great school in northen Italy), we hope we will publish the archive in a month and a half or so.
Sorry for being so slow but since being solar powered in the winter this project went a bit on hold.
here http://www.rcgroups.com/forums/showthread.php?t=1488457#post19041620 you can find a lot more photos tho :-)