Part 107 UAS pilot reported the UAS flew above authorized altitude twice when switching to automated return to home. The pilot took manual control of the UAS to bring it back down and land.

Narrative

I was conducting a UAV flight to capture images of a residential property at Location X around XA00 hours on Day 0. The flight path remained directly over or in close proximity of the property's boundaries. Prior to the mission; I received LAANC approval to fly up to 100' (within the boundaries of ZZZ Class C airspace). I maintained an altitude below 100' during the duration of the flight; and was at approximately 70-80' directly over the structure when a battery alert began to annunciate. Knowing I had ample battery power to complete the mission; I chose to capture my last image prior to manually landing the aircraft. When the battery power reached a pre-determined level; the UAV software initiated an automatic 'return to home' sequence I was not expecting. At this time; the aircraft automatically began a rapid climb to begin the sequence. Knowing I was relatively close to the 100' approval ceiling; I manually overrode the sequence; which I had to accomplish twice within an approximately 15 second window. For approximately 2 seconds; the aircraft traveled up to approximately 112' before I could manually lower it; then again; for approximately 3 seconds; it traveled up to approximately 119' before I could manually lower it. It was at these maximum altitudes for approximately 1 second each prior to being manually flown lower; below the 100' approval ceiling. I landed the aircraft without further issue. No injuries or aircraft damage resulted from this incident. In the future; I will consider landing the aircraft prior to the initiation of the 'return to home' sequence; and will maintain increased situation awareness regarding the return to home sequence/ altitude and the aircraft's remaining battery power.