Detect unused solar energy

Hi there,

I just had a 27kW fronius inverter with 90x340W solar panels installed.

Since the payment to send energy back into the grid is very low in my country, I would like to make use of all the solar energy available through heatpumps and sanitary water heating, without ohmpilot.

Currently the system limits the output based on my usage, but I dont know how much more is available from the solar panels.

Is there any way to detect the extra available power from the fronius API in realtime ? I managed to connect to the API(V1) and it responds, but I dont know which value shows this available power information.

My smart meter is: Smart Meter TS 5kA-3
The inverter is : Fronius Eco 27.0-3-S

Thank you

manually or automatically control something based on available power?
this is a good instantaneous view

or for android and maybe iphone, solar.web live or solar.web pro works ok but is slower and more delayed

Also the inverter has an option called load managment that can direct power elsewhere. Not sure how it works but of you have the meter configured it should be able to do it on excess power.

or another few options for either logging or viewing



Hi @xjustbmw

You can quite easily obtain realtime PAC figures using the Fronius API. My Fronius Symo relies upon version 1 of the API

You can check your API version with the following API call. [ Substitute the IP address of your inverter unless you’ve configured a HOST name for it ]


I get the following.

“APIVersion” : 1,
“BaseURL” : “/solar_api/v1/”,
“CompatibilityRange” : “1.6-3”

In Ver. 1 of the API


Will provide you with a wealth of information including the value PowerReal_P_Sum which will show you NETT power. If the value is NEGATIVE you are exporting electricity to the grid if it is POSITIVE you are IMPORTING electricity from the grid.

Depending on the sign and magnitude of this value you could control an external load. This would require a computer / Arduino / Raspberry Pi or some other form of microcontroller. You would essentially be mimicking the Fronius Ohmpilot.

Of course there are all sorts of safety issues once you start to switch mains voltage at the sorts of current that you are considering. You would also need to engineer into the software something that prevents your loads from being rapidly switched ON / OFF if the NETT power figure hovers around or crosses ZERO else you might damage something. E.G. If you switched in a 2000W load with only 1000W of surplus power the new NETT figure of 1000W [ IMPORT ] would / could trigger the shedding of the load a few moments later. This would be highly undesirable.

“Body” : {
“Data” : {
“0” : {
“Current_AC_Phase_1” : 5.601,
“Current_AC_Phase_2” : 6.1600000000000001,
“Current_AC_Phase_3” : 6.9379999999999997,
“Details” : {
“Manufacturer” : “Fronius”,
“Model” : “Smart Meter 63A”,
“Serial” : “1738XXXXX”
“Enable” : 1,
“EnergyReactive_VArAC_Sum_Consumed” : 27706220,
“EnergyReactive_VArAC_Sum_Produced” : 21653530,
“EnergyReal_WAC_Minus_Absolute” : 31500273,
“EnergyReal_WAC_Plus_Absolute” : 10928128,
“EnergyReal_WAC_Sum_Consumed” : 10928128,
“EnergyReal_WAC_Sum_Produced” : 31500273,
“Frequency_Phase_Average” : 50,
“Meter_Location_Current” : 0,
“PowerApparent_S_Phase_1” : 1350.9612,
“PowerApparent_S_Phase_2” : 1474.0880000000002,
“PowerApparent_S_Phase_3” : 1667.8951999999999,
“PowerApparent_S_Sum” : 4466.8999999999996,
“PowerFactor_Phase_1” : 0.98999999999999999,
“PowerFactor_Phase_2” : -0.98999999999999999,
“PowerFactor_Phase_3” : 1,
“PowerFactor_Sum” : 1,
“PowerReactive_Q_Phase_1” : 63.969999999999999,
“PowerReactive_Q_Phase_2” : -62.399999999999999,
“PowerReactive_Q_Phase_3” : -19.600000000000001,
“PowerReactive_Q_Sum” : -18.030000000000001,
“PowerReal_P_Phase_1” : -1340.78,
“PowerReal_P_Phase_2” : -1461.6600000000001,
“PowerReal_P_Phase_3” : -1664.46,
"PowerReal_P_Sum" : -4466.8999999999996,
“TimeStamp” : 1641178830,
“Visible” : 1,
“Voltage_AC_PhaseToPhase_12” : 416.10000000000002,
“Voltage_AC_PhaseToPhase_23” : 415.39999999999998,
“Voltage_AC_PhaseToPhase_31” : 417.10000000000002,
“Voltage_AC_Phase_1” : 241.19999999999999,
“Voltage_AC_Phase_2” : 239.30000000000001,
“Voltage_AC_Phase_3” : 240.40000000000001
“Head” : {
“RequestArguments” : {
“DeviceClass” : “Meter”,
“Scope” : “System”
“Status” : {
“Code” : 0,
“Reason” : “”,
“UserMessage” : “”
“Timestamp” : “2022-01-03T11:00:30+08:00”