I'm busy with an installation where we are installing 3x 8kVa Quattro's as a 3ph system which needs to act as battery backup to the property, entire property will be on AC out 2 (essential loads). There is Pylontech lithium batteries, 12x 3.5kWh.
The client has an existing PV grid-tie system with a Huawei KTL12 3ph inverter.
We received wrong information regarding the Huawei inverter and now that we started getting documentation regarding the Huawei's frequency shifting parameters we noticed that it doesn't support frequency shifting. We need to find a solution for this as the client is not allowed to feed back excess energy.
a) For now I'm considering to purchase a Huawei Smart logger and a Janitza energy meter to at least enable the zero export function on the PV inverter. The inverter will then be connected without any other loads on the AC out 1 of the quattro's so that it switches off in the event of a power failure (we cannot frequency shift so we don't want to damage batteries etc. if using on AC out 2 since the inverter will stay on at 100% output if it's getting a voltage reference from the inverters). Should this setup work? We know that the batteries will only get charge when AC input is on again since the inverter will only then switch on. The Janitza meter for inverter will be installed on the AC input side of the inverters.
b) When using a smart logger from Huawei it is possible to switch the Huawei inverter on and off with a digital input, will we be able to use the CCGX relay to switch this input on the smart logger on certain SOC levels? For instance switch the relay on at SOC 30% and off at 95-100%? The inverter will then output its production at 100% and switch off when the relay opens, and not gradually decrease its output as it would have with freqeuncy shifting, how should this affect the battery charge? If this option b is chosen we will put the inverter on AC out 2 so that the batteries can still charge in the event of a grid failure.
Both options above SHOULD be temporary solutions as my supplier says Huawei is working on new firmware to implement frequency shifting in their inverters, but that he's been asking them for over a year and they keep saying their working on it. When they eventually do the firmware update, we will change the system to a normal ESS system with frequency shifting on AC out 2 to control the inverter output.
Please mention any other workaround suggestions should there be any. Thanks in advanced.