1. Scenario Preset

(1) The scenario is based on a small on-grid Solar PV system without DC energy storage.

(2) In order to establish a complete monitoring system, we need to install a smart wireless 3-phase energy meter with bidirectional metering function on Grids Side (Need to monitor the girds' overall 3-phase incoming circuit so that we can monitor the total power consumption supplied from grids to house loads and also monitor the over-generated reflux energy from Solar PV to grids or power transformer.

(3) The reason why to choose wireless energy meter was because it could directly send data toAcrel loT Energy Monitoring System without using a extra loT Gateway. For separate installation.this will be more economic.

(4) Suppose grids sides incomming circuits is with rated current of 150A AC and rated voltage of230Vac LN&400Vac L-N.

2. Device Plan

Grids Side - Grids' Overall 3-phase Incoming Circuit:

1* ADW300-4GHW/C Wireless 4G Energy Meter.

2* AKH-0.66/K K-24 150/5 Split-core Current Transformer

3. Calculation Logic - When the Solar PV Generated Power < House Load Consumed Power

(1) When the solar PV generated power wasn't enough for house loads to consume. Grids will also distribute power to house load for consuming. So, in this situation, the house load total power consumption was consisted of 2 parts, solar PV generated power and grids distribution power

(2) Girds power flow to house load for consuming was normally calculated as "forward active energy, EPI" and "postive active power, +kw" by #1 ADW300-4GHW energy meter.

Calculation logic (When Solar PV not Enough)

Diagram of "Forward Active Energy, EPI"

4. Calculation Logic - When the Solar PV Generated Power > House Load Consumed Power
(1) When the solar PV generated power was larger than house loads power consumtpion. The part of over-generated solar PV power will reflux to power transformer or grids. In this situation, solar PV power generation will be distributed to 2 part, to house loads and to power transformer or girds

(2) Solar PV over-generated power which reflux to power transformer or girds was normally calculated as "backward active energy, EPE" and "negative active power, -kw" by #1 ADW300.4GHW energy meter.

Calculation logic (When Solar PV Over-generated)

Diagram of "Backward Active Energy, EPE"

5. Communication Structure&Logic - To loT System
(1) 4G Communication could be served as one of the final data upstream methods by sending the data to cloud server deployed in lnternet so that Acrel loT System could be interact with these data collected by bottom metering devices like Energy Meter

(2) ADW300-4GHW/C Wireless 4G 3-phase Energy Meter has a built-in 4G communication module which allow it to directly send data to local 4G telecom tower through 4G signal based on MQTT and MODBUS-TCP protocol without using a extra 4G loT Gateway.

(3) Each ADW300-4GHW/C has a 4G card tray for installing the 4G sim card which could be bought from your local 4G service provider.
(4) ADW300-4GHW/C also have a RS485 communication normally used for devices adjustment with Acrel ADW300 adjustment software.

6. Communication Structure&Logic - To Solar Inverter
(1) ADW300-4GHW energy meter also has a RS485 port [MODBUS-RTU protocol] which could be connected to Solar PV lnverter so that inverter could get the reading from ADW300 based on MODBUS-RTU protocol.
(2) Once the inverter get a reading of "backward active power (minus value]", the invert could automatically lower its power generation rates so that the over all Solar PV generated power won'be more than house load consumption. Thus Solar PV side won't have export to grids side and eventually realize zero export

Note:
1. Solar PV inverter get reading of bidirectional active power of grids side from ADW300 based on RS485 [MODBUS-RTU]
2. Once inverter get the reading of backward active power (export) , inverter will lower its power generation rates so that no more Solar PV over-generated power flow to grids side. [no more export power]
3. All the generation power control logic was decided by inverter, energy meter ADW300 only provide the reading of bidirectional active power. So the integration between ADW300 and inverter based on RS485 interface (MODBUS-RTU) protocol for get the reading of bidirectional active power must be done and inverter side must have this type of control logic. [When inverterget the reading of backward active power,it will lower its power generate rate]

7. Product Select Model