for a school project I have to do something that needs the environment to work, my plans are to make a solar powered mini fan, now my question. How can I make that the fan ( 6v dc motor) keeps working for little while even after I block the solar panel. Do I simply put a capacitor? If yes, how do I know wich capacitor( values) should I get?. Thanks for the help
Electronic – Solar powered mini fan
capacitorfansolar energy
Related Solutions
That was a long question :-) You are not out of your mind and think in the right direction.
In fact you can get twice much amps you need for your fan. So yes, get one of these modules, and add some extra capacitors on the output (some 10'000 uF) to help it deal with FAN's pulsed current consumption & startup current.
You can even get way bigger fan, cap will help to start it and it will work even if you have just 30-40% of the power it needs. You just need separate switch for DCDC board and FAN - so that you turn DCDC first, and after 1 second - FAN (so that cap is charged).
And finally, direct sun gives much much more juice than 60 Watt lamp. So you really need more powerful fan & more powerful DCDC.
I wouldn't recommend connecting the panels in series in case the 20V panel pumps too much current through the ones that don't work very well. To decide how to connect them (if it's possible) details of those panels would be required.
However, for the 20V panel I would say you need a switch mode buck regulator that takes the 20V and reduces it efficiently to 12V to power the two 12V motors. At 0.8A total draw from the two 12V motors the power requirement is 9.6W. The panel and regulator should be able to supply 90% of 20V x 0.8A = 14.4W.
This leaves about 4W (conservatively) for the 6V motor which you imply requires 0.6W. You'll need a second step down buck regulator for this device and it sounds feasible.
Switch mode buck regulators - there are tons of them but I can only recommend a design type such as the LT3976: -
For a slightly more efficient regulator there is the LTC3780 which will work providing 12V down below 12V from the panel: -
Both regulators can supply 12V at 5A.
I wouldn't bother thinking about a linear regulator because it will waste about 8W in heat.
It's possible that you can search along these lines and get some kind of module/PCB that you don't have to build. Maybe someone can recommend something?
Best Answer
A large capacitor would work, yes. Just get something rated for more than six volts (I'd recommend more than twelve, a wide margin is a good thing to have!) and a large capacitance; the larger, the longer it will continue to run, assuming the panel was able to fully charge the capacitor before it was blocked. If you want it to run for a very long time, you might want to look at electric double-layer capacitors, also known as supercapacitors, which can have very high capacitance.