Roy Lewallen wrote:

You've asked for a module that puts out 6-9 volts @ 100 mA. A more
accurate description of a solar panel would be that it puts out 100 mA
at 6-9 volts.

Also the currewnt outputdepends somewhat on the latitude you're at. You
won't get all that current at the arctic circle.

Watson A.Name "Watt Sun - the Dark Remover" wrote:
Also the currewnt outputdepends somewhat on the latitude you're at. You
won't get all that current at the arctic circle.

He might actually have a better chance there during the periods when the sun
never sets than at, e.g., the equator... solar cells are noticably more
efficient when they're keep cold, which is typically a lot earier to do in
the arctic than at the equator!

Watson A.Name "Watt Sun - the Dark Remover" wrote:
Also the currewnt outputdepends somewhat on the latitude you're at. You
won't get all that current at the arctic circle.

He might actually have a better chance there during the periods when the sun
never sets than at, e.g., the equator... solar cells are noticably more
efficient when they're keep cold, which is typically a lot earier to do in
the arctic than at the equator!

In article , "Joel Kolstad"
writes:

Watson A.Name "Watt Sun - the Dark Remover" wrote:
Also the currewnt outputdepends somewhat on the latitude you're at. You
won't get all that current at the arctic circle.

He might actually have a better chance there during the periods when the sun
never sets than at, e.g., the equator... solar cells are noticably more
efficient when they're keep cold, which is typically a lot earier to do in
the arctic than at the equator!

Ahem, Joel, consider the location of "the land of the midnight sun..."

:-)

Ackshully, based on a little bit of experience on Solar One, the
first (of two) experimental 50 MWe solar plant in Barstow, CA,
(in the middle desert of California with not much else), sunlight
has a considerable variance in energy over the course of a day.
A combined buck-boost switching power supply would be a
consideration for reliable solar cell charging of a secondary
battery during daylight. There are several different ICs just for
the purpose of wide-voltage-range inputs from National, Linear,
and Maxim along with application notes from all three.

Roy Lewallen hit the subject nail on the head in saying, correctly,
that solar cells behave more as constant-current sources than
constant-voltage (as batteries are) sources. Those who care to
test that will find out from connecting a fixed resistor to solar cell
outputs and measuring the voltage during the course of daylight,
especially the differences between clear and cloudy skies.

Solar One was a boiler system, over 500 independent mirrors were
used as a giant reflector array to focus sunlight on a central boiler
made from the same stainless-steel-like tubing used in rocket engine
bell structures. Rocketdyne Division of Rockwell International was
the subcontractor to MacDonnell-Douglas that made the boiler and
the underground steam-heat storage system of Solar One. The peak
daylight energy was in excess of 100 MWe equivalent but the extra
heat had to be stored overnight for the steam-turbine-powered
generators to run 24/7. Rocketdyne, now purchased by Boeing,
made the Space Shuttle Main Engines. Rocket engine bells
are made from tubing to circulate fuel before entering combustion.
That pre-warms the fuel as well as cooling down the tail of the
engine's output.

Not exactly what a QRP operator would need... :-)

Len Anderson
retired (from regular hours) electronic engineer person

In article , "Joel Kolstad"
writes:

Watson A.Name "Watt Sun - the Dark Remover" wrote:
Also the currewnt outputdepends somewhat on the latitude you're at. You
won't get all that current at the arctic circle.

He might actually have a better chance there during the periods when the sun
never sets than at, e.g., the equator... solar cells are noticably more
efficient when they're keep cold, which is typically a lot earier to do in
the arctic than at the equator!

Ahem, Joel, consider the location of "the land of the midnight sun..."

:-)

Ackshully, based on a little bit of experience on Solar One, the
first (of two) experimental 50 MWe solar plant in Barstow, CA,
(in the middle desert of California with not much else), sunlight
has a considerable variance in energy over the course of a day.
A combined buck-boost switching power supply would be a
consideration for reliable solar cell charging of a secondary
battery during daylight. There are several different ICs just for
the purpose of wide-voltage-range inputs from National, Linear,
and Maxim along with application notes from all three.

Roy Lewallen hit the subject nail on the head in saying, correctly,
that solar cells behave more as constant-current sources than
constant-voltage (as batteries are) sources. Those who care to
test that will find out from connecting a fixed resistor to solar cell
outputs and measuring the voltage during the course of daylight,
especially the differences between clear and cloudy skies.

Solar One was a boiler system, over 500 independent mirrors were
used as a giant reflector array to focus sunlight on a central boiler
made from the same stainless-steel-like tubing used in rocket engine
bell structures. Rocketdyne Division of Rockwell International was
the subcontractor to MacDonnell-Douglas that made the boiler and
the underground steam-heat storage system of Solar One. The peak
daylight energy was in excess of 100 MWe equivalent but the extra
heat had to be stored overnight for the steam-turbine-powered
generators to run 24/7. Rocketdyne, now purchased by Boeing,
made the Space Shuttle Main Engines. Rocket engine bells
are made from tubing to circulate fuel before entering combustion.
That pre-warms the fuel as well as cooling down the tail of the
engine's output.

Not exactly what a QRP operator would need... :-)

Len Anderson
retired (from regular hours) electronic engineer person

maxfoo wrote:
On Mon, 12 Apr 2004 00:11:36 -0700, Roy Lewallen wrote:


If you're looking for a module that includes a built in voltage
regulator to limit the voltage to 6 - 9 volts, you need to make it
clear. Most of the responses seem to be referring to 12 volt panels,
which will be fine if you limit the voltage, but won't be suitable if
you need voltage regulation to be included in the external module.


my pcb has a Linear Tech LT1117-5 LDO regulator on board, regulates 5volts with
a min input Voltage of 6 volts, so I'm currently using 4 AA batteries in a
battery pack with a 9v type clip. Wanted to be able to charge the batteries with
solar cells basically.

But after searching the web a bit it seems cheapest to buy individual cells
then tie them in series...No?

For 6V, I would put two of these in series, along with a 1N5817 schottky
diode to prevent reverse current. Each cell is encapsulated with epoxy
and the wires can be soldered to the pads on the back. Each puts out an
honest 30 mA, or more in bright sunlight. Price is reasonable too.

http://www.allelectronics.com/cgi-bi...-60&type=store

You can also put two pairs in parallel to get a faster charge.

thanks,

maxfoo wrote:
On Mon, 12 Apr 2004 00:11:36 -0700, Roy Lewallen wrote:


If you're looking for a module that includes a built in voltage
regulator to limit the voltage to 6 - 9 volts, you need to make it
clear. Most of the responses seem to be referring to 12 volt panels,
which will be fine if you limit the voltage, but won't be suitable if
you need voltage regulation to be included in the external module.


my pcb has a Linear Tech LT1117-5 LDO regulator on board, regulates 5volts with
a min input Voltage of 6 volts, so I'm currently using 4 AA batteries in a
battery pack with a 9v type clip. Wanted to be able to charge the batteries with
solar cells basically.

But after searching the web a bit it seems cheapest to buy individual cells
then tie them in series...No?

For 6V, I would put two of these in series, along with a 1N5817 schottky
diode to prevent reverse current. Each cell is encapsulated with epoxy
and the wires can be soldered to the pads on the back. Each puts out an
honest 30 mA, or more in bright sunlight. Price is reasonable too.

http://www.allelectronics.com/cgi-bi...-60&type=store

You can also put two pairs in parallel to get a faster charge.

thanks,

Avery Fineman wrote:
In article , "Joel Kolstad"
writes:

He might actually have a better chance there during the periods when the
sun never sets than at, e.g., the equator... solar cells are noticably
more efficient when they're keep cold, which is typically a lot earier
to do in the arctic than at the equator!

Ahem, Joel, consider the location of "the land of the midnight sun..."

That's why I said 'during the periods when the sun never sets' -- it's about
half the year with no light, and half with no darkness, no? :-)

After all, during the 'no light' periods he doesn't have to run the air
condtioner anyway, right? Just kidding!

Avery Fineman wrote:
In article , "Joel Kolstad"
writes:

He might actually have a better chance there during the periods when the
sun never sets than at, e.g., the equator... solar cells are noticably
more efficient when they're keep cold, which is typically a lot earier
to do in the arctic than at the equator!

Ahem, Joel, consider the location of "the land of the midnight sun..."

That's why I said 'during the periods when the sun never sets' -- it's about
half the year with no light, and half with no darkness, no? :-)

After all, during the 'no light' periods he doesn't have to run the air
condtioner anyway, right? Just kidding!

But after searching the web a bit it seems cheapest to buy individual cells
then tie them in series...No?

thanks,



My experience with tying together solar cells is that you'll probably
destroy a few along the way (the pads lift very easily when heated
with soldering iron), so either get extras or go with a solution which
does not require you to solder cells together (or be more careful than
I was, I guess).