A composite electrical load monitoring system comprising: one or more computer systems; and a computer-readable medium storing instructions executable by the one or more computer systems to perform operations comprising: determining, at a first time instant during a duration, a first margin between a first reading of a first electrical parameter and a first electrical parameter limit for a first power source (302, 304, 306, 308); determining, at the first time instant during the duration, a second margin between a second reading of a second electrical parameter and a second electrical parameter limit for a second power source (302, 304, 306, 308); determining, after the first time instant, that the first margin is less than the second margin in response to determining (402, 404) the first margin and the second margin; displaying, in a display device and within the duration, an identifier for the first power source (302, 304, 306, 308) in response to determining that the first margin is less than the second margin; determining, at a second time instant during the duration and after the first time instant, a third margin between a third reading of the first electrical parameter and the first electrical parameter limit for the first power source (302, 304, 306, 308); determining, at the second time instant, a fourth margin between a fourth reading of the second electrical parameter and the second electrical parameter limit for the second power source (302, 304, 306, 308); determining, after the second time instant and within the duration, that the fourth margin is less than the third margin in response to determining the third margin and the fourth margin; and replacing, in the display device and within the duration, the identifier for the first power source (302, 304, 306, 308) with an identifier for the second power source (302, 304, 306, 308) in response to determining that the fourth margin is less than the third margin. one or more computer systems; and a computer-readable medium storing instructions executable by the one or more computer systems to perform operations comprising: determining, at a first time instant during a duration, a first margin between a first reading of a first electrical parameter and a first electrical parameter limit for a first power source (302, 304, 306, 308); determining, at the first time instant during the duration, a second margin between a second reading of a second electrical parameter and a second electrical parameter limit for a second power source (302, 304, 306, 308); determining, after the first time instant, that the first margin is less than the second margin in response to determining (402, 404) the first margin and the second margin; displaying, in a display device and within the duration, an identifier for the first power source (302, 304, 306, 308) in response to determining that the first margin is less than the second margin; determining, at a second time instant during the duration and after the first time instant, a third margin between a third reading of the first electrical parameter and the first electrical parameter limit for the first power source (302, 304, 306, 308); determining, at the second time instant, a fourth margin between a fourth reading of the second electrical parameter and the second electrical parameter limit for the second power source (302, 304, 306, 308); determining, after the second time instant and within the duration, that the fourth margin is less than the third margin in response to determining the third margin and the fourth margin; and replacing, in the display device and within the duration, the identifier for the first power source (302, 304, 306, 308) with an identifier for the second power source (302, 304, 306, 308) in response to determining that the fourth margin is less than the third margin. determining, at a first time instant during a duration, a first margin between a first reading of a first electrical parameter and a first electrical parameter limit for a first power source (302, 304, 306, 308); determining, at the first time instant during the duration, a second margin between a second reading of a second electrical parameter and a second electrical parameter limit for a second power source (302, 304, 306, 308); determining, after the first time instant, that the first margin is less than the second margin in response to determining (402, 404) the first margin and the second margin; displaying, in a display device and within the duration, an identifier for the first power source (302, 304, 306, 308) in response to determining that the first margin is less than the second margin; determining, at a second time instant during the duration and after the first time instant, a third margin between a third reading of the first electrical parameter and the first electrical parameter limit for the first power source (302, 304, 306, 308); determining, at the second time instant, a fourth margin between a fourth reading of the second electrical parameter and the second electrical parameter limit for the second power source (302, 304, 306, 308); determining, after the second time instant and within the duration, that the fourth margin is less than the third margin in response to determining the third margin and the fourth margin; and replacing, in the display device and within the duration, the identifier for the first power source (302, 304, 306, 308) with an identifier for the second power source (302, 304, 306, 308) in response to determining that the fourth margin is less than the third margin.