PW cuts off the grid connection and goes battery only when the Grid is working fine [New Zealand]

[Monkfamilynz]

Hi all
I have a strange issue where the PW cuts off the grid connection and goes battery only when the Grid is working fine. This happens at periods of peak load when our system is set to charge from the grid and we are charging the cars (night time) The loads are often below 20kW range and it has been working fine for about two months. We have 2 x PW2's and a Gen 1 gateway. The gateway is set to a site import limit of 20kW. What has happened in the past if we go over 20kW import the PW's drop their charge rate to try to maintain an import level of under the 20kW, usually about 19.8kw give or take. Any ideas?

 

[JohnRatsey]

What is the mains voltage at your house when the PW disconnects from the grid? The voltage drop on the supply will increase as the total load increases and I would assume that the PW is programmed to switch to battery when the mains voltage drops excessively in order to protect household equipment. I can't find this threshold in the Tesla documentation but it could well be around 10% below the nominal mains voltage. It's also possible that your mains voltage is below the nominal value under low load conditions which will exacerbate the situation. The risk of this increases with distance from the nearest transformer.