Contention between 2 Hybrid inverters

[audiongraeme]

I currently have 2 x Kstar KSE4000 hybrid inverters running in single phase from the same supply through 2 x ezmeters.. The backup supply from each of the inverters feeds two halves of my fuse box (seperate supply per inverter). The main output from the inverter goes straight into the standard grid input to the fusebox

Each inverter has access to a battery bank consisting of 20 x 170AH lead crystal batteries and 5KWH of recycled laptop lithium packs in 1.25KW chunks..

I have a solar Iboost+ taking excess power for hot water and eventually the remaining excess to heat my hot tub in summer ( I still have to make an inductive load heater and pump for it)

The problem I have is that teh 2 inverters don't work harmoniously with each, I have tried using an RX to TX RS485 lead between the two inverters but there seems no way to make one a master and the other a slave.. Goodwe have been far from helpful here, by just sending me a user manual.. It shows multiple inverters paralleled and each having its own ezmeter and its own load.

The problem seems to be that the system is constantly micro charging / discharging and that despite being connected to the same battery each inverter shows a different SOC and uses the battery power differently.

DOes anyone know anything about Kstar or Goodwe ES Hybrid inverters or can suggest a way to make the 2 work together, or would I be better off scrapping the 2 and just getting a single 10KW hybrid single phase inverter and if so any suggestions please?

 

[timselectric]

I currently have 2 x Kstar KSE4000 hybrid inverters running in single phase from the same supply through 2 x ezmeters.. The backup supply from each of the inverters feeds two halves of my fuse box (seperate supply per inverter). The main output from the inverter goes straight into the standard grid input to the fusebox

Each inverter has access to a battery bank consisting of 20 x 170AH lead crystal batteries and 5KWH of recycled laptop lithium packs in 1.25KW chunks..

I have a solar Iboost+ taking excess power for hot water and eventually the remaining excess to heat my hot tub in summer ( I still have to make an inductive load heater and pump for it)

The problem I have is that teh 2 inverters don't work harmoniously with each, I have tried using an RX to TX RS485 lead between the two inverters but there seems no way to make one a master and the other a slave.. Goodwe have been far from helpful here, by just sending me a user manual.. It shows multiple inverters paralleled and each having its own ezmeter and its own load.

The problem seems to be that the system is constantly micro charging / discharging and that despite being connected to the same battery each inverter shows a different SOC and uses the battery power differently.

DOes anyone know anything about Kstar or Goodwe ES Hybrid inverters or can suggest a way to make the 2 work together, or would I be better off scrapping the 2 and just getting a single 10KW hybrid single phase inverter and if so any suggestions please?

If the battery cables feeding the two inverters, aren't the same size and length. Due to voltage drop, the two inverters will see a different voltage (SOC).

 

[audiongraeme]

Both battery cables are the same length, both 50mm2 and going through the same trip switches to a single buss bar.. The lengths of the cables to each bank of 4 batteries is varying lengths, but as they all terminate at the same buss bar that should not make a difference I would have thought..

But I do see your point, and will check tightness of connections etc and placement of the cables going to the inverters on the buss bar stack..

 

[timselectric]

You could also take voltage readings, at the battery inputs to both inverters. Most inverters, when in parallel. Require being powered by a common battery bank. If the voltages are off, the inverters think that they are connected to different battery banks.

 

[audiongraeme]

Thanks.. I'll try that ... Haven't thought of checking the voltages at the inverters.. just made the assumption that they would be the same..