Maximum Power Point Tracking MPPT

When talking all things solar, there are two distinct and only loosely related concepts called ‘tracking’, and it is important to be clear about which is which. The two concepts are:

• Maximum Power Point Tracking (MPPT) – an electronic function that adjusts voltage / current parameters to get the most power out of a solar panel; and
• Mechanical Tracking – a method to physically move the panels to keep them facing at the sun, or an angle that changes with time (such as east in the morning, west in the afternoon). This is most relevant for installations where there is a cap on the number of kilowatts that can be installed, or in off-grid applications such as when more starting torque is required on a remote battery-less pumping system.

In this section, we are discussing the tracking most relevant for small household systems : Maximum Power Point Tracking. Often abbreviated to MPPT, this is an inverter based electronic architecture that controls the Photovoltaic (PV) modules in a way that ensures the solar panels will produce all the power they are capable of (at that moment). As discussed briefly above, MPPT is nothing to do with mechanical tracking systems that physically move the modules to make them point to the sun, but they could be used together.

MPPT uses electronics and programming to vary the electrical operating point (usually the voltage) of the modules so that the modules are able to deliver maximum available power. This monitoring is informed by the knowledge that the Current (I)-Voltage(V) curve – also known as the IV curve – is knee shaped, the implication being that by slightly moving the voltage level a significantly higher current can be achieved (recall DC power is simply volts x amps). Additional power harvested from the modules is then made available to the conversion circuits, and ultimately results in more power going onto the grid or the other circuits in your meterbox. All Greenforce Energy Home Solar Power systems contain inverters with MPPT functions, and some larger inverters have multiple tracking units.