Ok here goes - what wll be a long post i suspect.. apologies but easisest to try and reply to it all at once.
WiNet
when using the dongle, it can be conencted either via wifi or ethernet, and uses that mode for the following activities, its web UI (accessed by its ip address at port 80.. aka normal browser); it uploads selected data to iSolar cloud, it provides a TCP modbus function on port 502 (that kaiser HA modbus uses to interogate registers & populate HA sensors)
The kaiser modbus integration has a file sungrow_modbus.yaml (its huge) that lists all the registers/sensors AND for each the “scan interval” it uses .. that is how often it tries to retrive the information frommodbus connectiion.
it has 4? different “categories” of scan_interval, with default times for each. The most frequent “real time” has a default of 5sec, fast (10sec .. default?) : medium and another even slower category - that are less frequent. However even with the 5sec interval, the winet dongle “cannot” deliver these rates (from my observations ..) .. it slows them down to cope with its loading & its updates to isolar.
However - when i moved my modbus interface for HA to com2 port “logger” RS485 connections (via RS485 - ethernet modbus adaptor) I now get reliable 5Sec reporting for ALL the “real time” AND “fast” (i changeed it also to 5sec) register/sensors .. HA cannot go faster that 5sec .
After doing this - it helps with “accuracy” of calculations for power loss/efficiency .. read on… and obviously the dashboards update faster etc .
To calculate power loss (DC to AC) & efficiency - requires using a number of power sensors to effectiviely compute power IN - power OUT … and obviously you need them “all at the same time” .. to avoid obvious errors.. and even with the fast update rate - i still see some weird spikes in the calculation … so to smooth these - i use some 20sec averaging of the power loss & efficiency - before its graphed (see above) … even then - its quite spikey.
The Losses.
definitely NOT constant & it ranges from 200-700+ Watts.. its very clearly a function of the DC operating point and the AC loads.. For certain it shows its “best (~97.5%) effixciency at DC inputs of 14-18kW.. (with my 20T) … id estimnate its sweet spot to be ~75% of its peak power rating … which kind of makes sense.. but to your question, definietly NOT, I see power losses of well over 700W at times, and certainly 500+ when the solar id doing it thing (~15kW) .. remember that its a%; so even at high efficiency eg 97% .. if its runniung at 15kW .. thats 450W of losses. yes overnight at lower loads, i loose 250W ish ..
Now I see you have an IHome manager in your system & looking at the connection diagrams, it uses this same “com2 logger RS485” port (that i mention above). and it connected direct to the CT/s .. and hence it may be? the source of some? of your register/sensors.. not clear if the inverter is also connected direct to the CT/s? and if it sees the meter data directly? hence its a bit unclear (to me) if you get the data from it (only) or a combo of it & the inverter via winet? (& presumbly the different modbus port your quoting) ..so i think this is the root of your challenges .. and obvioulsy where my setup differs to yours (i have only one source of inverter/grid/battery data) .. you may have two?
the sungrow iHome manager install manual shows a few different inteconnection sceanrios … do you know how yours is wired?
