Please click here to download the Advantages of Morningstar’s Parallel Charging Using Multiple Controllers With Separate PV Arrays white paper. Large off-grid and battery backup PV systems, often require greater charging than a single controller can provide. To meet the charging requirements of these large systems, several TriStar™ or TriStar MPPT™ controllers can be connected in parallel to a battery bank. Each controller is connected to its own separate PV array. This document provides answers to frequently asked questions, and tips concerning the operation and setup of these large multiple TriStar and TriStar MPPT controller systems.