Charge controllers have come a long way from the simple relays of thirty years ago that opened when the batteries reached full charge voltage. Those relays were replaced by solid state charge controllers that used Pulse Width Modulation to control the amount of voltage applied to the batteries. The drawback to PWM units, still popular for very small systems, is that they control the power to the batteries from the PV by discarding excess voltage, with the result that the PV array must be oversized in order to charge the batteries under the worst conditions.  With the introduction of Maximum Power Point Tracking to charge-controller technology, the power output of the PV array is optimized to the state of charge of the batteries as well as the ambient temperature of the array and the amount of sunlight available.

With 80-Amp continuous output, the Apollo Solar T80 TurboCharger™ begins with the capability to process up to 30% more power than its leading competitor. In addition, the T80 makes use of a proprietary MPPT algorithm that harvests the maximum amount of power from the PV array under all external conditions and even starts working earlier in the day than the competition does. And, perhaps best of all, the T80 is built upon a robust thermal design that, combined with high-efficiency power circuits, minimizes heat generation. The internal temperature-controlled variable-speed fan runs just fast enough to enable the T80 to produce full-rated power without de-rating up to 45°C ambient. With simplified layout and low-parts-count, the T80 is able to maximize airflow and reduce the internal operating temperature, the most important factor in providing optimum electronics reliability.