LED Solar Tracker (Blatant dvertisement from Red Rock Energy)
Duane C. Johnson
I've been working with solar trackers for a number of
years. Recently I discovered that ordinary LEDs work
well as Photo Voltaic Photo Sensors. See:
http://www.redrok.com/electron.htm#led1
I have designed a neat little single axis solar tracker
using the LED sensor concept. It works very well.
The circuit is designed to drive satellite dish linear
actuators. Although almost any low voltage DC motor
should work.
See a picture and a schematic at:
http://www.redrok.com/electron.htm#led3
The PC board is .7"x1.4" and uses mostly surface
mount parts.
I'm also selling the completed circuit for $35us.
The power connector is included.
Shipping in the US is about $1.00us.
A kit of parts is for sale for $20.00us.
Some have said that a tracker for PV panels is not
cost effective. I say it is, usually. I live in
Minnesota. Using the NREL data base:
http://rredc.nrel.gov/solar/pubs/redbook/redbook_index.html
I calculate a 40% increase in delivered energy in
December and 100% increase in June.
Other parts of the country will have different results.
For instance San Jose, CA only gets 14% for both
June and December. You have to do the calculations
for your own area.
Some have said that a fourth panel costs less than
the tracker and mount. A 100W panel costs about
$400us. However, a tracker costs less than this and
delivers more energy for less cost.
Another advantage is the timing of the delivered
power. A solar tracker delivers its power over a
greater percentage of the day. This can reduce the
amount of charge cycling on the battery system.
Thanks! Duane
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These are my opinions, and not that of Unisys Corp. ===
gigawatt
>
> I've been working with solar trackers for a number of
> years. Recently I discovered that ordinary LEDs work
> well as Photo Voltaic Photo Sensors.
Cadmium Sulfide Sensors work really well... they are
cheap and available at Radio Shack... you need two
for them for a horizontal tracking system... or.. four
of them for both horizontal, and vertical tracking...
You use a bridge circuit... and put two CS cells seperated
by black cardboard on the upper legs of the bridge circuit...
then when the sun is out.. it shines more on one cell than
the other... this will cause the DC motor between the
bridge outlets, to either run forward, or backwards.... when
the sunlight is balanced... then no current will flow...
You could even use a small PV panel to power the bridge...
so that when the sun is obscure, or it is dark, then there
will be no flow of current...
Gig
Duane C. Johnson
gigawatt <giga...@nospam.com> wrote:
> > I've been working with solar trackers for a number of
> > years. Recently I discovered that ordinary LEDs work
> > well as Photo Voltaic Photo Sensors.
> Cadmium Sulfide Sensors work really well... they are
> cheap and available at Radio Shack... you need two
> for them for a horizontal tracking system... or.. four
> of them for both horizontal, and vertical tracking...
You must have missed my posting of the CdS relay tracker.
See the schematic of a relay version at:
http://www.redrok.com/electron.htm#cds
or one that Dave Chace and I developed a few years ago:
http://www.redrok.com/electron.htm#chace1
> You use a bridge circuit... and put two CS cells
> seperated by black cardboard on the upper legs of the
> bridge circuit... then when the sun is out.. it shines
> more on one cell than the other... this will cause the
> DC motor between the bridge outlets, to either run
> forward, or backwards.... when the sunlight is
> balanced... then no current will flow...
I think you are describing an analog balanced bridge
circuit. I have found that balanced bridge circuits
tend to dissipate to much power in the output transistors.
Even though there is to little current to move the motor
the current is significant. In the actuators i use this
current can be as high as 50mA even though there is no
movement. To this I have found that a pair of balanced
light sensors work better.
The first sensor pair tends to move the tracker easterly
and the other tends to move the tracker westerly. When
the tracker is centered on the sun the two pairs cancel
each other. This stops movement without any current to
the actuator.
The circuit I now use is shown here:
http://www.redrok.com/electron.htm#led3
> You could even use a small PV panel to power the
> bridge... so that when the sun is obscure, or it is
> dark, then there will be no flow of current...
Take a look at Paulek's tracker. Here's my link:
http://www.redrok.com/main.htm#paulek
> Gig
gigawatt
"Duane C. Johnson" <red...@redrok.com> wrote in message
news:3A48B90F...@redrok.com...
> Hi Gig;
> You must have missed my posting of the CdS relay tracker.
> See the schematic of a relay version at:
> http://www.redrok.com/electron.htm#cds
> or one that Dave Chace and I developed a few years ago:
> http://www.redrok.com/electron.htm#chace1
It seems like you got it already down to a fine art....
I will look at your page... and save the schematics
for future referrals...
Thanks,
Gig