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MPPT charge controllers can increase the output from your solar panels by up to 30%, depending on the panel specifications. It is important to match up the panels controller and battery voltages correctly for best performance though.
MPPT charge controllers allow PV panels to operate at their maximum power point, wheras PWM regulators force the panel to work at battery voltage, which is usually at a power level significantly below their peak. MPPT charge controllers also allow panels to be connected in strings, allowing lower currents between panel and controller, reducing cable resistive losses and/or the size of cable required.
If a regulator is broken, chances are it will be an open circuit and wont damage the solar panel, but it does depend on what sort of "broken" it is!