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

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!

On Mon, 12 Apr 2004 13:52:35 -0700, "Joel Kolstad"
wrote:

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.

The difference for panels perpendicular to the sun on the equator and
the arctic circle in the summer noon is about 10-15 %, due to the
atmospheric absorbtion. The difference between the equator and pole is
about 30 % in the same conditions.

If the panel is tracking the sun, the panel on the pole during the
summer will produce electricity for 24 h each day, while the other
panel on the equator will produce for less than 12 h. On the arctic
circle about 18-20 h each day will give usable electric output.
Exactly at the arctic circle, the midnight sunlight is strongly
attenuated by the atmosphere, so you can look at it even with your
naked eyes or ordinary sunglasses, thus the electric output is also
minimal.

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!

The silicon cell behaves quite in the same way as a silicon diode
which has a 0,7 V threshold voltage and -2 mV/C temperature constant,
thus the cell output voltage (and hence power) drops with temperature.

However, the cells are heated by solar radiation at nearly at constant
flux on the equator and arctic circle, thus, the main issue is how
well the heat will be removed from the cell to the environment. At the
arctic summer the air temperature can be well over 20 C for longer
periods of time, so this does not help a lot in keeping the cells
cool.

Paul

Paul Keinanen wrote:
At the
arctic summer the air temperature can be well over 20 C for longer
periods of time, so this does not help a lot in keeping the cells
cool.

....and the windchill is also reasonably comparable? I didn't realize the
arctic could be so 'balmy!' Thanks for the info.

I suppose that if you wanted to push the issue, a heat pipe stuck in the ice
going back to a metal layer on the back of the panel would be quite
effective in cooling the panel...

Paul Keinanen wrote:
At the
arctic summer the air temperature can be well over 20 C for longer
periods of time, so this does not help a lot in keeping the cells
cool.

....and the windchill is also reasonably comparable? I didn't realize the
arctic could be so 'balmy!' Thanks for the info.

I suppose that if you wanted to push the issue, a heat pipe stuck in the ice
going back to a metal layer on the back of the panel would be quite
effective in cooling the panel...

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

On Mon, 12 Apr 2004 13:52:35 -0700, "Joel Kolstad"
wrote:

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.

The difference for panels perpendicular to the sun on the equator and
the arctic circle in the summer noon is about 10-15 %, due to the
atmospheric absorbtion. The difference between the equator and pole is
about 30 % in the same conditions.

If the panel is tracking the sun, the panel on the pole during the
summer will produce electricity for 24 h each day, while the other
panel on the equator will produce for less than 12 h. On the arctic
circle about 18-20 h each day will give usable electric output.
Exactly at the arctic circle, the midnight sunlight is strongly
attenuated by the atmosphere, so you can look at it even with your
naked eyes or ordinary sunglasses, thus the electric output is also
minimal.

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!

The silicon cell behaves quite in the same way as a silicon diode
which has a 0,7 V threshold voltage and -2 mV/C temperature constant,
thus the cell output voltage (and hence power) drops with temperature.

However, the cells are heated by solar radiation at nearly at constant
flux on the equator and arctic circle, thus, the main issue is how
well the heat will be removed from the cell to the environment. At the
arctic summer the air temperature can be well over 20 C for longer
periods of time, so this does not help a lot in keeping the cells
cool.

Paul