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Traditional controllers connect the solar module directly to the battery when recharging. This requires that the solar module
operate in a voltage range that is usually below the module's maximum power voltage. In a 12 Volt system for example, the
battery voltage may range from 10 - 15 Vdc, but the module's Vmp is typically around 16 or 17 Volts. The figure below
shows typical current vs. voltage and power output curves for a nominal 12 Volt off-grid module.
The array maximum power voltage is the voltage where the product of output current and voltage (Amps x Volts) is great-
est, which falls on the "knee" of the solar module I-V curve as shown on the left in the figure above.
Because traditional controllers do not always operate at the maximum power voltage of the solar array, energy is wasted
that could otherwise be used to charge the battery and power system loads. The greater the difference between battery
voltage and the maximum power voltage of the module, the more energy is wasted. MPPT technology will always operate
at the maximum power point resulting in less wasted energy compared to traditional controllers.
