Here is wherethe optimization, or maximum power point tracking comes in. Assume your batteryis low, at 12 volts. A MPPT Controller takes that 17.6 volts at 7.4 amps andconverts it down, so that what the battery gets is now 10.8 amps at 12 volts.Now you still have almost 130 watts, and everyone is happy.

Ideally, for100% power conversion you would get around 11.3 amps at 11.5 volts, but youhave to feed the battery a higher voltage to force the amps in. And this is a simplifiedexplanation – in actual fact the output of the MPPT charge controller mightvary continually to adjust for getting the maximum amps into the battery.

       A MPPT SolarController tracks the maximum power point, which is going to be different fromthe STC (Standard Test Conditions) rating under almost all situations. Undervery cold conditions a 120 watt panel is actually capable of putting over 130+watts because the power output goes up as panel temperature goes down – but ifyou don’t have some way of tracking that power point, you are going to lose it.On the other hand under very hot conditions, the power drops – you lose poweras the temperature goes up. That is why you get less gain in summer.