Morningstar Sunsaver TrakStar 15 Amp MPPT Charge Controller 12V/24V Efficient MPPT tracking and 4-stage charging increases battery life Gel, Sealed, AGM. M aximizes Energy Harvest peak efficiency of over 97% Smaller Size Mechanical dimensions are less than other MPPT controllers, making it easier to install Efficient electronics, a conservative thermal design and tropicalization result in high reliability The status LED's and optional meter provide extensive controller and system data.