SOC is not P_Akku

[oli-arborum]

The SOC of a connected battery is supplied in another field, not P_Akku:

{
   "Body" : {
       "Data" : {
           "Inverters" : {
              "1" : {
                 "Battery_Mode" : "normal",
                 "DT" : 1,
                 "E_Day" : null,
                 "E_Total" : 483344.81527777779,
                 "E_Year" : null,
                 "P" : 352.25048828125,
                 "SOC" : 90.900000000000006
              }
           },
           "SecondaryMeters" : {},
           "Site" : {
              // ...
           }
      }
}

Thus, the SOC needs to be queried with data.Body.Data.Inverters[1].SOC (and not data.Body.Data.Site.P_Akku).