I asked a poorly worded question previously. I would like to ask the sparkfun community if they have successfully used an arduino uno using a solar system? Can anyone make a recommendation?
I have numerous projects in mind that would benefit from use of an Uno in a remote location. It seems likely that someone has already solved this one so I came here after failing to google-up anything definitive.
One example would be to make a charge controller for a 24 volt battery bank. I tried to supply the Uno via the 7 to 12 volt input jack with a circuit based on a LM78L09 voltage regulator. This was supplied directly from the 24 volt battery bank. The V reg datasheet give 35V as abs max so not a problem. At first it seemed ok, But sometimes when the load kicked in (load being a DC motor) the voltage drops below 12 volts momentarily and the Uno operation was interrupted.
I would like to work up a reliable solar power supply , stand alone, for these micros…any thoughts/suggestion appreciated.
Think of it this way; Your system is powered by a rechargeable battery not the solar panel. The solar panel is a separate system that recharges the battery when solar flux is available.
The battery needs to be able to supply the peak current required by your application. It also needs to be able to continuously supply the average current the application requires. If your battery voltage drops to the point the Arduino resets then that’s an instantaneous current management problem and really has nothing to do with the solar panel. Maybe a big capacitor would help. Or maybe you need separate batteries for the motor and Arduino.
The solar panel must replace the current consumed by the application. The application requires power 24/7. The solar panel supplies power intermittently, only when there is enough sunshine. The two sides must at least balance in terms of power and time (Watt-Hours). Since there are inefficiencies in the system, and cloudy days, the solar panel needs to supply enough power to make up the difference plus a safety margin.
SparkFun sells the Sunny Buddy which helps manage current and battery charging. Adafruit has a similar product. Just search solar on the various sites.