Connection Standard Small Scale Parallel IES up to 30kVA FAQs
Effective 1 July 2014, a new connection standard for Small Scale Parallel Inverter Energy Systems (IES) up to 30kVA was introduced. This was a joint initiative between Energex and Ergon Energy.
What are the major changes to the standard?
The major changes to the Connection Standard Small Scale Parallel Inverter Energy Systems (IES) up to 30 kVA include:
- Customers must be aware of the impact of installing a Battery Energy Storage Systems (BESS)
- IES systems are now rated in kVA instead of kW
- Technical Assessments are not required for 100% export limited systems
- Changes to prescribed inverter settings
- Information in relation to allowable internal voltage rise - to be no more than 2%
- Mandatory requirements for reactive power settings
Additional Information on each of these points is detailed further in the points below.
Who's an accredited person?
An accredited person is a person accredited to the Clean Energy Council to design and/or install renewable energy systems. Categories of accredited persons include:
In all instances, a person authorised under the Queensland Electrical Safety Act (2002) is required to certify the installation.
Where do I need to install Power Limiting Devices?
This Standard allows for nil export to the network (i.e., self consumption) as an option up to 30kVA when a larger system is requested but fails to meet our initial assessment criteria. In this case the installer shall submit a single line diagram showing the location of the power export limiting device in relation to other circuits, settings for operation of the device and site details. This drawing will be included as an appendix to the network connection offer. We won't be maintaining a list of approved power limiting devices.
What drawings or documentation is required with my applications?
Applications for installations incorporating power limiting devices and/or battery energy storage systems are required to submit an approved drawing with the application. This drawing is to be signed by a Clean Energy Council accredited designer or an Registered Professional Engineer of Queensland (RPEQ). Changes are being made to our Electrical Partners Portal (EPP) to allow these documents to be submitted with the application. However, in the interim if you can please email these drawings to firstname.lastname@example.org, referencing the NMI for the site and the portal application number.
To meet minimum requirements when submitting drawings for Battery Storage and Nil Export Systems, please submit a detailed single line diagram (SLD) showing all major components of the system and their interconnections, including the mains and customer load. Note this diagram is required to be displayed on a single document and needs to display the following information:·
- A drawing number for contractual purposes
- Site details including NMI number and premise address
- The installer's name and CEC accreditation number
- The name and model number of inverters, battery chargers and export limiting devices used
- FOR NIL EXPORT ONLY - the export limit and the associated time delay of the limiting device (Note the current connection agreement stipulates the export limit be less than 2% of inverter capacity with a time delay of less than 10 seconds)
- FOR BATTERY SYSTEMS ONLY - the battery details, including name/model number and capacity (Volts and Amp hours)
How does the Standard allow for Battery Energy Storage Systems?
The requirements are covered in Section 6.7 of the standard, and both AC and DC coupled systems are allowed for. We request that all customers installing a Battery Energy Storage System (BESS) advise us through the Electrical Partners Portal (EPP). An approved single line diagram showing connection details of the BESS and information on the charge/discharge characteristics must be provided so they can be included in the network connection contract.
Note that customers on an existing feed-in tariff will lose this tariff on installation of a BESS, due to the potential to store energy at a cheaper rate and discharge to the grid for a higher price. Similarly additional inverters and PV panels added to an existing approved PV system will be considered an addition to the existing system, and hence will be re-assessed with customers losing their feed in tariff.
We acknowledge the benefits of the excess energy produced by a solar PV system being stored in batteries for use during peak demand periods. Customers can benefit by offsetting more of the cost of grid-supplied electricity and from having a back-up system in the event of a power supply interruption on the network
.Any application for an IES system incorporating a BESS will be subject to the same technical assessment as any other exporting IES.
Why are the IES systems now rated in kVA instead of kW?
Traditionally, the capacity of an inverter has been defined in kilowatts (kW). However, newer inverters allow settings to be changed to enhance the system's performance. When the power factor, or reactive power control, setting is changed, kW no longer correctly defines the inverter's capacity. This is the key reason for the move to defining inverter capacity in kilovolt Amperes (kVA).
Note : Power from PV arrays is always measured in kilowatts (kW).
When are Technical Assessments required?
Solar PV systems won't be subject to technical assessment if they're 100% export limited through the installation of a separate power-limiting device. This change will enable customers to install larger systems than would be approved by us if they were exporting power to the grid.
This is expected to appeal to customers whose main goal is to offset their own electricity use rather than receive a feed-in tariff for the excess power their solar PV system generates.
We won't be keeping a register of approved power limiting devices. However, the customer or their representative will need to produce a design drawing for the system signed by an accredited CEC designer confirming that the proposed system conforms to the requirements of this standard. An application for a nil-export system received without an acceptable schematic drawing will be rejected.
What rules apply for the aggregation of micro-inverters?
The aggregation of micro-inverters (or small scale inverters associated with individual panels) are subject to the same rules and conditions as any other IES.
What are the prescribed inverter settings?
Inverter settings shall be in accordance with Table 3 - Prescribed Inverter Settings:
Vmax (Two Stage)
|Energex - 257V, Ergon Energy - 255V (10 min average); 260V (2 sec trip)|
|Disconnect time||2 seconds|
|Reconnect time||60 - 90 seconds|
|Reactive Power Control||0.9 lagging Fixed Power Factor|
Failure to comply with the 257V requirement for overvoltage setting can result in dangerous internal voltages, as well as contributing to voltages above statutory limits on the distribution network (some inverters can be set as high as 270V in accordance with AS4777).
How do I prevent internal voltage issues?
Customers (or their representatives) must ensure that operation of the inverter doesn't cause a voltage rise of more than 2% between the inverter and network coupling point. This has been an issue particularly with larger single phase systems on rural and acreage blocks. Problems have occurred with these systems tripping off the overvoltage setting on the inverter.
What are the mandatory requirements for reactive power settings?
Based on feedback from the industry and at the workshops held in March 2014, the mandatory requirement in the standard for Reactive Power Settings on solar PV systems with export capacity greater than 3kVA will not be applied until 30 September 2015.
The performance of both the network and inverter systems can be improved by enabling the reactive power control functionality on some inverters. This occurs because it lowers the voltages and reduces, or potentially eliminates nuisance tripping and may therefore increase the total amount of power exported to the grid.
As a result, the new standard requires that all systems capable of exporting more than 3kVA must have a Power Factor Control (reactive power) setting activated at a designated value. Setting an inverter to a power factor of 0.9 lagging will not reduce all generation by 10%.
- A fixed power factor of 0.9 lagging, will only affect the real power export when the inverter is at >90% of its rated capacity. This generally occurs a very small amount of the time.
- Having reactive power control allows a customer to connect a larger IES than they would have otherwise been able to, and increases the penetration of IES a network can handle.
- An IES with reactive power control will trip less frequently. For reasons (2) & (3) above, the benefits of setting the inverter power factor at 0.9 lagging outweigh the potential negatives in (1). However, to allow installers to clear old stocks and to fall in line with the proposed timing for updates to AS4777, this requirement has been deferred til 30 September 2015.