dumass wrote:
Does anyone have suggestions for a good (i.e good quality and good
price) solar panel supplier for the charge system ?

This is the panel and vendor I used for the panel mounted on my trailer,
and it seems to be good quality.

http://www.batterymart.com/battery.mv?p=VDC-SCC015

Amorphous construction panels, like this one, are typically much cheaper
than the crystalline panels. They are also physically larger per watt,
but generally this isn't an issue when mounted on a trailer or placed
next to the glider at a tiedown.

Did anyone do calculations for required panel size ?

For an estimate, try this for estimating the minimum panel size:

[charging amphours required] = (your typical current drain) x (your
typical flight duration)

[hours of sunlight] = number of hours the panel will have for charging
the battery, including the hours after you land and the hours in the
morning before you take off.

[solar panel current] = amphours / (hours of sunlight before your next
flight)

For my glider:

..7 amps x 6 hours = 4.2 amphours
1 hour after landing + 4 hours in the morning = 5 amps (summertime)
4.2/5 = .84 amps

I have a 1 amp, 15 volt panel (also known as a 15 watt panel). I also
have a huge battery, so I don't have to have a full charge every day,
otherwise, I'd have a bigger panel.

Notes:

1) "Hours of sunlight" means any time the panel is out and charging, but
not the first or last two hours of the day when the sun is weak.
2) You have to align the panel with the sun every few hours to use the
calculated value.
3) If you don't want to re-align the panel with the sun, or it's mounted
on a trailer, or you want to charge during days with 50% or more cloud
cover, get a panel twice the size.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA