An MPPT charge controller accurately calculates the maximum power voltage (Vmp) of the photovoltaic array. Maximum Power Point Tracking (MPPT) uses the power of the PV array at that Vmp and transfers this to the battery voltage whilst increasing the charging current. If there was 100% efficiency (assuming no wiring loss etc.) then power in is equal to power out. In general, a basic MPPT charge controller yields 10 to 15% increase in charging capability compared to a PWM regulator. This is an essential component in any larger off-grid PV system, ensuring that the maximum power is harnessed from the PV array.