For sailplanes, there's an upside though. The PV manufacture's specs list
panel temperature for rated output. Since PV panels make more voltage at
colder temps, and as you go up it gets colder, you can turn this into more
power from a given PV array.

Assuming you pay just a bit more for your solar charge controller and buy a
Maximum Power Point Tracker type, your MPPT controller will trade the higher
output voltage for up to 30% more current from a given PV panel.

MPPT charge controllers, suitable for glider use, are available for under
$100.

bumper
purveyor of QuitVent & MKII "high tech" Yaw String
Minden, NV

"Vaughn Simon" wrote in message
...

"JS" wrote in message
ups.com...
These equipment-based topics come to mind immediately.

Batteries.
Solar panels.
Transponders.
Transponder antenna mounting.
Altitude encoders.
Alternatives, ie: FLARM.

Anytime you are discussing the combination of solar panels and
batteries, we also need to be discussing charge controllers. Since you
have broached the subject of Lithium Ion batteries, you would need to find
a controller that is approved for those batteries. Be aware that the
dangers of Lion batteries, largely (but not exclusively) concern charging.


There are a few interesting photovoltaic panels available. For example,
a 5 Watt "Powersheet" can be mounted on the fuselage above the spar.

Not to discourage PV panels, but you only get your entire five watts when
the entire panel is flat and pointed directly at full sunlight, and
probably not even then. With solar panels, always derate the
manufacturer's claims by at least 50% to approach real-life expectations
of results. (As they say, your mileage may vary)

Vaughn