I changed the preferences section to fix the configuration page error. I believe the range specifier syntax was the problem.
preferences {
input("kWhCost", "string",
title: "Electric Bill Cost Per KWh (dollars)",
description: "Electric Bill Cost Per KWh (dollars)",
defaultValue: "0.19514" as String,
required: false,
displayDuringSetup: true)
input("monitorInterval1", "integer",
title: "Voltage and Energy Report Interval (s)",
description: "Voltage and Energy Report Interval (s)",
defaultValue: 60,
range: "1..3600",
required: false,
displayDuringSetup: true)
input("monitorInterval2", "integer",
title: "Current Report Interval (s)",
description: "Current Report Interval (s)",
defaultValue: 30,
range: "1..3600",
required: false,
displayDuringSetup: true)
input("monitorInterval3", "integer",
title: "Power Report Interval (s)",
description: "Power Report Interval (s)",
defaultValue: 6,
range: "1..3600",
required: false,
displayDuringSetup: true)
}