TN004 Australian & New Zealand Export Power Control Functionality

Transcription

1 TN004 Australian & New Zealand Export Power Control Functionality The sonnen product range including the eco8 single and three phase domestic energy storage system (ESS) has with its external componentry and internal management system the ability to effectively manage as well as limit the power it exports to the loads circuits and prevent any flow to the grid from its own stored energy. This functionality is also known as export limitation or feed-in limitation. The Sonnen meter (Gavazzi EM271DS kwh Meter) will measure power using both a voltage reference and current transformer (60A split core CT). The CT is installed within the AC supply cabling prior to the domestic loads, i.e. between the grid, the Solar PV input, the Sonnen system input and the loads. In addition to measuring overall power flow to the load circuits the sonnen system will also measure and monitor any power being produced and supplied from any grid connected solar PV installation via a second set of CT s. From the gathered data the sonnen system will ascertain the renewable energy production value, the overall power flow volume and direction to evaluate whether any power is required to either charge the batteries or supplement the domestic load requirement by providing power from the batteries. The meter connects to the sonnen unit via a hard wired Modbus/RS485 connection to maintain a closed-loop feedback control protocol over its own output. 1

2 The accuracy of the meter is equivalent to class 1 (kwh) of EN and equivalent to Class 2 (kvarh) of EN (EM271 Base only), the CT monitoring accuracy is also equivalent to class 1 (TCDM split-core current sensors accessory only). Single Phase Line Diagram 2

3 Three Phase Line Diagram 3

4 Export Limitations & Exporting Power to The Grid System The sonnen system by default is factory configured to maximise self-consumption on the domestic load side of the utility connection point. Energy generated by any associated AC coupled solar PV system will be used to charge the batteries contained within the sonnen system as well as provide power flow to the domestic load circuits with any excess flowing back to the grid. If, however export limitation has been required to be implemented by the utility company from the associated solar PV system then this method of limitation will be managed by the solar PV inverter and any associated control system external to and out of the scope of control of the sonnen system. The inverter within each Sonnen system continually polls to the meter to determine whether power is required to be supplied to the load circuits as well as whether any power being exported to the grid. Whenever export is detected, the inverter reduces its output and if necessary, the inverter output is reduced to zero. Thus the inverter ensures that energy from the battery is never exported to the grid. If the batteries within the sonnen system are fully charged and power being supplied from an AC coupled solar PV array / inverter (separate solar inverter) is greater than the power required to satisfy the load circuits, then this power can be exported to the grid. However, it is worth noting that this power does not come from the batteries in any way. AS/NZS :2015 states that passwords are an appropriate tool for preventing internal settings against inadvertent or unauthorized tampering of the export value. Although this may be true of a solar PV grid-connect inverter and/or hybrid PCE it is not an option with the sonnen system as the function of limiting export to the grid is factory set to zero. Homeowners and/or installers are not supplied with a password for allowing export to the grid from stored energy within the sonnen batteries. If the sonnen system loses either communication with the meter or if the grid were to fail, then the entire system goes into standby mode whereby no power is supplied whatsoever and no power is drawn to charge the sonnen batteries. The sonnen system will remain in standby mode until such time and the meter connection is restored and/or the utility power supply resumes. The sonnen system reaction time to respond to load fluctuations and guarantee no export to the grid typically occurs within 1 second and settles within a maximum of 5 seconds. On the following pages you will find detailed specification of the meters used with the sonnen eco8.2/2 to eco 8.2/16 range of products to ensure export limitation functionality. If you have any further questions about the appropriate fixing or securing of the sonnen systems within earthquake prone region, please contact us at any time for further support or assistance. Yours faithfully, James Sturch Technical Business Manager Australia & New Zealand 4

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