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francois asked

Quattro and Huawei PV inverter

Hi,


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.

MultiPlus Quattro Inverter ChargerSOCRelayfrequency
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Murray van Graan avatar image Murray van Graan commented ·

If the Huawei is an existing setup, how does it limit feedback currently? Also note that you won’t be able to frequency shift in ESS..

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francois avatar image francois Murray van Graan commented ·

@Murraynated the client had to switch off the system for a few months and we actually told him we can limit feedback with frequency shifting, this was before we found out the Huawei doesn't support it

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1 Answer
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tilo answered ·

You confused AC Out 1 and 2. AC Out 1 is always on, for essential loads (with AC In and with battery+inverter), AC Out 2 is off when AC In is off, unless you configure it in another way.

You can connect the Huawei inverter to AC Out 2 and switch AC Out 2 depending on SOC and AC Input, like this you don´t need the extra Huawei logger for switching the Huawei inverter on and off.

If you want to use the CCGX relay to switch, you can connect it to a digital input of the Quattros, who in turn can use this signal to switch AC Out 2. If you do that, you must separate the signal wiring to the 3 inverter inputs from each other, because you cannot connect the inverter signal input terminals in parallel, as this might disturb the electronics of the Quattros. You can use 3 micro relays driven by the CCSG output (powered with 48V from the battery), one relay for each Quattro.

Use assistants in VE.Configure 3 ( like "programmable relay") to configure AC Output 2.

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francois avatar image francois commented ·

@tilo thanks this sounds good:

You can connect the Huawei inverter to AC Out 2 and switch AC Out 2 depending on SOC and AC Input, like this you don´t need the extra Huawei logger for switching the Huawei inverter on and off.

But the only disadvantage I think of is that it will charge full by +-11am and then switch the output off, when the sun goes down by +-6pm the batteries might be at 50% as it discharged during the day but not low enough to activate the output again to switch the solar on.

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