sizing solar panel

Eric Greenwell wrote:
It would have be about a 1 amp maximum output panel just to be sure of
getting 0.5 amps on average, which would leave ~2 amphours to the
battery after a 4 hour flight. About 1+ hours of use would remain at
your 1.5 amp drain. That's a rather large solar panel to mount on
glider, or a rather expensive one.


Using PowerFilm PT15-75 thin film flexible modules rated at 50ma, 15.4
volts, it would take 20 units to get 1 ampere. Cost $800 ($40@). These
would use 5 square feet plus of surface area. They are 10.6" x 3.9".
There were several of these or similar units on gliders at the SSA
convention. The edges were taped to mount them and at that size they
seemed to form well to the compound curve of the fuselage. Only two or
three on a glider which indicates to me that they were mostly for the
wow factor..
Randy

I have been flying with the set up for three seasons.
Since my power supply is adequate for all my instruments but for the radio
which is an old 1980 ATR 720 and it appears to work well if adequate power
is provided. I will go with Tom's suggestion of packing a larger battery.

The routine at a contest would be as follows.
We get our tasked. It will be entered. The radio and the L Nav is switched
off, the GPS and PDA will be on from this time on.
If you are in the middle of the pack it could take 25 minutes till launch.
Radio and L Nav is turned on at launch. Waiting for an other 25 minutes to
get started, maybe more plus a three hour task. Total over 4 hours.

Base on what I can figure the idle radio uses .4 amp, the L Nav, the PDA and
the GPS uses .35 amp combined, as per CAI. Borgelt uses ~.15 amp

I would say a normally charged 7 amp battery with the surface charge taken
off and reading about 12.7 volts to start with, it would not surprise me if
I would see 12 volt or slightly less on the meter after 4 hours.

As it is now all works well but at the end of the flight I should not forget
to
switch batteries and I been known to forget it. If the ground guys have a
good radio my radio will be ok for the normal operation even if I do not
switch batteries certainly air to air was never a problem unless I had the
radio turned off.
Udo

Eric Greenwell wrote:
It would have be about a 1 amp maximum output panel just to be sure of
getting 0.5 amps on average, which would leave ~2 amphours to the
battery after a 4 hour flight. About 1+ hours of use would remain at
your 1.5 amp drain. That's a rather large solar panel to mount on
glider, or a rather expensive one.


Using PowerFilm PT15-75 thin film flexible modules rated at 50ma, 15.4
volts, it would take 20 units to get 1 ampere. Cost $800 ($40@). These
would use 5 square feet plus of surface area. They are 10.6" x 3.9".
There were several of these or similar units on gliders at the SSA
convention. The edges were taped to mount them and at that size they
seemed to form well to the compound curve of the fuselage. Only two or
three on a glider which indicates to me that they were mostly for the
wow factor..
Randy

Birdbones wrote:

Using PowerFilm PT15-75 thin film flexible modules rated at 50ma, 15.4
volts, it would take 20 units to get 1 ampere. Cost $800 ($40@). These
would use 5 square feet plus of surface area. They are 10.6" x 3.9".
There were several of these or similar units on gliders at the SSA
convention.

The "or similar" units were Strobl units, and are not similar at all.
It's a different type of cell (crystalline) that provides several times
the current for a given area compared to the Powerfilm (amorphous)
units. They are also several times more expensive, about 4 times
thicker, and are the panel supplied by the German glider manufacturers.

The edges were taped to mount them and at that size they
seemed to form well to the compound curve of the fuselage.

I think they are glued on, and the taping is part of the fairing and
sealing, not mounting. On the ASH 26 E (and probably the other
Schleicher motorgliders), they are flush mounted on the engine bay
doors, an elegant way to do it.

Only two or
three on a glider which indicates to me that they were mostly for the
wow factor..

Not true for the Strobl units, which were capable of 1+ amps on the
gliders I saw at the convention.

I've looked at the Powerfilm units for my glider as they are less than
half the price per amp and easier to mount, but they require so much
area for the amps I require, I decided against them. I think they would
be a good choice for someone looking for 200-300 milliamps.

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Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Birdbones wrote:

Using PowerFilm PT15-75 thin film flexible modules rated at 50ma, 15.4
volts, it would take 20 units to get 1 ampere. Cost $800 ($40@)

This site

http://store.sundancesolar.com/powul...l?page=viewall

offers them for $26, which would make them much more attractive.


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Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Eric,
I downloaded your manual, excellent. Currently I only fantasize about a
self launcher.
I then went to the Strobl-solar.de website but my Deutsch ist nicht so
gut. Google was unable to translate it or find a site in english. Do
you know of a U.S. source on the web for these Strobl panels?
Randy

Strobl- Solar
Beschreibung:
Artikel Nr.800328
SFL 7,5 monokristallines, flexibles Solarmodul
Leistung: 7,5 Watt, 400m Amp.
Abmessung:L x B x H 660 x 108 x 1,3mm
Gewicht: 145 gr

Einzelpreis: 378,95 EUR

that one is a narrow strip for one doors only, like the DG 800
one strip = 375.95 Eur
The other unit is similar but different dimension.
If you want to know more about the product I can help translating
Udo

Although I have never measured it, I recall the average current drain for my
Becker transonder is only a couple hundred ma. The reason is that only
pulses are sent out and the average power consumed is pretty low.

Colin

Hi
I can only confirm that the Strobl units are far superior to many other
units as I am using them on my DUO. 1to1,5 hrs in the sun in the
morning usually recharges the 7amp Batterie completly (which you use to
start flying with) you switch to charge the other batterie during
flight and you can keep on switching them like this and you usually end
up a long day with 1 Batterie fully charged and the second one down to
about 12.5V. This is especially handy if you are using the transponder
as well. Sofar never switched more than
once during a flight. A Strobl Solarpanel on the Trailer to charge a
portable Buffer Batterie is the Cherry on the Cake. We fly with
Solarpower so lets charge our Batteries with Solarpower.

COLIN LAMB wrote:
Although I have never measured it, I recall the average current drain for my
Becker transonder is only a couple hundred ma. The reason is that only
pulses are sent out and the average power consumed is pretty low.

Not everyone has (or can afford) a Becker transponder. A Terra will
happily consume several times that amount. And, try measuring the drain
from the encoder at altitude, particularly if it's one with a heater...

Marc