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Solar power has become quite a star in green power generation recently. Especially here in Sydney, with the help of government policies, more and more buildings have solar power system on their rooftop.
As makers ourselves, making a small solar phone charger is becoming a fashion. There are many great entries in instructables about solar charger with portability in mind. They are great if you spend a lot of time outdoors.
Well people, I’m proudly present this instructable to you so that you can make your very own solar powered phone charging system with sun tracking.
Why tracking?
The sun moves 15 degrees every hour, angle of the incident solar rays directly affect the power output of the solar cell. A solar tracking gives 60% more power from the same solar cell.
Your will need
A solar cell – at least 6V, 1 Watt
A motor with gearbox
A circuit board
2x LM393 comparator IC, can be any similar comparator
A L293D H bridge motor driver IC
A IRF9450 MOSFET, or any similar P channel MOSFET
5k, 100k, 10k resistors
A 50k potentiometer
An IRF540 or similar N-MOSFET
One phototransistors (Darlington IR)
2 photocells or 2 photodiodes
Battery holder
Some 1N4004 diodes
Wires
Some sort of housing – I used my iPod touch case
And some batteries, I use NiMH here, you can also use Li-ion but the circuit may need to change
Tools:
Soldering iron
Hot glue gun and hot glue
Drill could be useful too
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Signing UpStep 1Let the theory begin (too boring? Jump to next step then)
Solar cell is a current source; its output current varies with solar intensity. Therefore we can just charge a NiMH pack without additional circuit to limit the current. To harvest maximum amount of ‘juice‘out of the solar cell, we should pick a battery pack that matches the voltage output of the cell at its maximum power point.
We will need a diode to prevent current flow into the solar cell, which may contribute a 0.7 to 1V drop. And normally solar cell’s voltage is marked using the open circuit voltage. you may need to lower a 10% or so to get to the VMP.
If you are getting a 6V solar cell, then it is best to charge 3 NiMH in series. I have used an 8V solar cell, and I have 4 batteries charging in series, so about 2V each cell.
We will need a diode to prevent current flow into the solar cell, which may contribute a 0.7 to 1V drop. And normally solar cell’s voltage is marked using the open circuit voltage. you may need to lower a 10% or so to get to the VMP.
If you are getting a 6V solar cell, then it is best to charge 3 NiMH in series. I have used an 8V solar cell, and I have 4 batteries charging in series, so about 2V each cell.
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engineer.casper@yahoo.com
Cheers
you can enlarge the schematic by clicking the 'i' button on the left top of the image.
if you want i can put the complete circuit into EAGLE, but that may take a while because i'm fairly busy with my uni work.
the open circuit voltage of a solar panel is important. you can't get any indication on the voltage of the solar panel from its max power output.
maybe you can try ebay to source your panel.
cheers
I sincerely hope
cheers
all my life i was dreaming of something like this but i don't have an experience i read computer science but do you think if i can put afford i will be good in it if possible then what advice will you give me
I enjoy make things since I was small, experience and knowledge came from my hobbyist work. To be good at something you should first love it. Find the satisfaction every time you achieve something. After a while you will find yourself put more work into the field. And that is the advice I can give you.