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Best/Easiest/Safe way to boost solar panel current

R

RC

Jan 1, 1970
0
I'm doing a science experiment with my son. We have three 1.5V solar panels
wired in parallel in order to supply the 1.5V/400mA needed to power a small
DC fan. This works fine in sunlight or some other really bright light
source. He needs to do a demo in a classroom and my flashlight doesn't
supply enough photons to do the job. What's the best way to give the solar
panel enough help so that it still takes a flashlight to power the motor. A
(AAA) battery supplies too much current to connect it in parallel with the
panels. What's the best way to supply just enough current so that I'm still
under the motor threshold until I shine a flashlight on the panel? I don't
have an ammeter handy yet, so I can't tell you what sort of current the
panels are capable of supplying right now with the flashlight.

Thanks for your help
 
K

Karl Uppiano

Jan 1, 1970
0
RC said:
I'm doing a science experiment with my son. We have three 1.5V solar
panels wired in parallel in order to supply the 1.5V/400mA needed to power
a small DC fan. This works fine in sunlight or some other really bright
light source. He needs to do a demo in a classroom and my flashlight
doesn't supply enough photons to do the job. What's the best way to give
the solar panel enough help so that it still takes a flashlight to power
the motor. A (AAA) battery supplies too much current to connect it in
parallel with the panels. What's the best way to supply just enough
current so that I'm still under the motor threshold until I shine a
flashlight on the panel? I don't have an ammeter handy yet, so I can't
tell you what sort of current the panels are capable of supplying right
now with the flashlight.

Thanks for your help

What happens if you connect the solar panels in series? You'll end up with
4.5 volts (theoretically), but the motor is not likely to be very picky
about that. Ohms law predicts that the higher voltage should get more
current going through the system.
 
E

Eric Sears

Jan 1, 1970
0
I'm doing a science experiment with my son. We have three 1.5V solar panels
wired in parallel in order to supply the 1.5V/400mA needed to power a small
DC fan. This works fine in sunlight or some other really bright light
source. He needs to do a demo in a classroom and my flashlight doesn't
supply enough photons to do the job. What's the best way to give the solar
panel enough help so that it still takes a flashlight to power the motor. A
(AAA) battery supplies too much current to connect it in parallel with the
panels. What's the best way to supply just enough current so that I'm still
under the motor threshold until I shine a flashlight on the panel? I don't
have an ammeter handy yet, so I can't tell you what sort of current the
panels are capable of supplying right now with the flashlight.

Thanks for your help
In short - it will be very difficult. Its doubtful whether the
flashlight produces more than a few milliamps with cells of that size
- which is hardly enough to even kickstart the motor with some volts
already on it. You might be able to put something like a 100 ohm pot
in series with the battery and motor and manage to adjust it; or it
might need a 1000 ohm pot - I'm just stabbing in the dark (try some
fixed resistors first to get an idea).

However, it might be better if you configure all the cells in series,
and use a white led (eg from a defunct solar garden light), instead of
the motor. It takes very much less current to show a result!
Usually about 3 or 4 milliamps will make them glow reasonably
brightly.

Eric Sears
 
R

RC

Jan 1, 1970
0
Eric Sears said:
In short - it will be very difficult. Its doubtful whether the
flashlight produces more than a few milliamps with cells of that size
- which is hardly enough to even kickstart the motor with some volts
already on it. You might be able to put something like a 100 ohm pot
in series with the battery and motor and manage to adjust it; or it
might need a 1000 ohm pot - I'm just stabbing in the dark (try some
fixed resistors first to get an idea).

However, it might be better if you configure all the cells in series,
and use a white led (eg from a defunct solar garden light), instead of
the motor. It takes very much less current to show a result!
Usually about 3 or 4 milliamps will make them glow reasonably
brightly.

Eric Sears

Thanks. I'll try a battery with a current limiting pot. The motor would
make a better demo, but I just may have to change the load to something else
like the light that you suggest.
 
J

jasen

Jan 1, 1970
0
I'm doing a science experiment with my son. We have three 1.5V solar panels
wired in parallel in order to supply the 1.5V/400mA needed to power a small
DC fan. This works fine in sunlight or some other really bright light
source. He needs to do a demo in a classroom and my flashlight doesn't
supply enough photons to do the job. What's the best way to give the solar
panel enough help so that it still takes a flashlight to power the motor. A
(AAA) battery supplies too much current to connect it in parallel with the
panels. What's the best way to supply just enough current so that I'm still
under the motor threshold until I shine a flashlight on the panel? I don't
have an ammeter handy yet, so I can't tell you what sort of current the
panels are capable of supplying right now with the flashlight.

Thanks for your help

a desk lamp may have enough power, if the classroom has a projector that can
project a white image that'll have plenty of power. if you're expecting sun an shaving mirror may
be able redirect enough sunlight to run the fan.

Using a battery is cheating, probably not something you want to teach your
son.

Bye.
Jasen
 
R

RC

Jan 1, 1970
0
jasen said:
a desk lamp may have enough power, if the classroom has a projector that
can
project a white image that'll have plenty of power. if you're expecting
sun an shaving mirror may
be able redirect enough sunlight to run the fan.

Using a battery is cheating, probably not something you want to teach your
son.

Bye.
Jasen

Cheating? I'm just trying to demonstrate the photovoltaic effect. No
photons, the motor doesn't turn...photons, the motor turns. I would explain
why the battery was needed for indoor use, and I actually think it makes for
a more interesting problem to work on.
 
R

Ronbo

Jan 1, 1970
0
RC said:
Cheating? I'm just trying to demonstrate the photovoltaic effect. No
photons, the motor doesn't turn...photons, the motor turns. I would explain
why the battery was needed for indoor use, and I actually think it makes for
a more interesting problem to work on.
Not cheating. In actuality that is the proper way to demo photovoltaic
cells.

Photovoltaic cells are rarely used to drive objects directly but are
used to charge batteries.

However if u need to drive a small fan try obtaining and using a small
micropressor fan. I have seen these at rating well under 100 ma and can
usally run at low speeds with only a few volts even though they spec at
12volts.
 

neon

Oct 21, 2006
1,325
Joined
Oct 21, 2006
Messages
1,325
use the solar panel to charge the battery . if the battery are fuly charged the fan will run at a good speed however it will slow down gradualy lack of power that is when you can introduce any kindof light and it you can vesibly see a fan speed up. that is your demonstation/
 
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