XTRA SERIES 12V/24V 30A MPPT SOLAR CONTROLLER WITH LCD DISPLAY New XTRA series has Lithium battery support (set via PC cable only) The XTRA tracer models have a current limiting function, you can connect twice the rated power to the controller so if your on a budget you can use a smaller controller with more panels so that you get more power in winter or low light but don't risk overloading the controller in the summer.  The output will be limited to the max listed above. XTRA series are advanced maximum power point tracking (MPPT) charge controllers, for off grid photovoltaic systems, with display unit. In order to maximise the energy harvest from PV arrays and simultaneously minimise the power loss within a wide range of operating conditions, XTRA series apply an advanced smart algorithm which results in up to 30% higher efficient charging, compared to a conventional pulse width modulation (PWM) charge controller. Xtra series controller have limit protection function on charging