Now why would you do THAT?

    OK, so we are getting closer to reality here.  Since the last article , I have made some small changes, which helped things out. Firstly, I added a 1000uF/63V filter capacitor to the battery output.  This practically eliminated the serious "hunting" issue that caused the software to rapidly ramp PWM values up and down almost constantly. Next I added two relays to the control circuit. The first is a battery cutoff, which will disconnect the battery if it is above 15V or below 9V, as these would indicate some kind of fault has occurred. The other relay disconnects the solar panel on the same principal.  If either of these events occur, the LCD indicates the nature of the fault. In order for battery monitoring to work effectively, the voltage divider must be located between the relay and the battery .  This way the battery can be reconnected automatically when the fault clears.  I have elected NOT to do this on the solar panel side as an over-voltage condition probably mean

Last time I introduced my new solar power project.  By the end of that post we were monitoring the power flow from the solar panel to the battery in a simple test environment.  This time we're going to dive in and start trying to control the charge power. What's MPPT? Maximum Power Point Tracking (or Transfer , depending on whom you ask) is a condition where we can transfer the highest power from the solar panel into the battery.  The key here is power, rather than voltage or current on their own.  Remember that power is the product of voltage and current, so it is possible that you will find that perhaps higher current and lower voltage (or vice versa) is the most efficient. What makes this a little problematic is that the peak power point varies constantly depending on the battery state of charge and temperature, so it is not a set and forget operation. This is why the first thing we did was to build a power monitor.  Now we can determine at any point of time, the power bein