How to transfer a query result into a positive number

I have a working Flux query

data = from(bucket: "solaranzeige")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "modbus.0.holdingRegisters.40074_Netz_Leistung")
  |> filter(fn: (r) => r["_field"] == "value")
  |> aggregateWindow(every: v.windowPeriod, fn: integral, createEmpty: false)
  |> yield(name: "EinspeisungHeute")
  |> filter(fn: (r) => r.value <= 0)
  |> integral(unit: 1h)

the result is a negative number - What do I need to add to the query to get a positive number?