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You, your distributor and your retailer all rely on a metering system in general and, in particular where a DG system is also installed at your premises, the interests of each of the parties in a metering system are as follows | 1. | Because your DG may have the capacity to generate electricity in excess of your immediate electricity needs, you want to know how much excess generation is exported back to the network. The metering system installed will have the capability to separately measure the amounts of electricity you take off the network and the amounts of excess electricity you inject back into the network. | | 2. | There are two reasons why the distributor relies on a metering system at your premises. Firstly, the price the distributor charges the retailer to deliver electricity to your premises has a component based on the amount of electricity delivered to you, measured in kWh1. Thus, the distributor needs access to the metered consumption data so as to determine its charges for network services. Secondly, by law the distributor is the party responsible for the overall quality of network supplied electricity, regardless of whether all the electricity flows from the network or whether some is injected (exported) back into the network from a DG. Hence, the distributor is likely to be particularly interested in parts of its network where there are significant levels of exported electricity occurring. While this is not so much of an issue today, it is one that distributors are keeping a close eye on and metered export data is a useful tool for this. This also explains why distributors publish network connection standards and request a comprehensive schedule of technical information on prospective DG installations before consenting to their connection to the network. Schedule 1 of the 2008 DG Regulations referenced above and distributors’ own website published DG connection guides are further useful references to the specific information required in support of each DG connection application.
As a final point here, note that under the 2007 DG Regulations, the distributor may recover from you the reasonable costs incurred by them of connecting your DG to the network and operating their network with your DG connected, net of any identified benefits provided by the connection and operation of your DG system. For small-scale DG, specifically the installation of systems of under 10 kW capacity, it has been argued that these costs and benefits are generally small and approximately net out to zero; in fact, in current practice, distributors are not generally requiring up-front or ongoing connection charges where there is no new connection equipment provided by them in the process of connecting your DG system.
Further, the distributor may charge you for costs it incurs in processing your DG connection application and for any inspection it might carry out once your system is installed. Both of these charges are subject to regulated caps; currently in May 2008 for installations of 10 kW or less capacity these are $200 for processing applications and $60 for inspecting installations. | | 3. | Your retailer sells electricity to you at your point of connection with the network. They rely on the metered quantities of electricity you consume to make up your bill.
With no DG present within the premises, this situation applies to the vast majority of NZ. When DG is introduced into the picture, unless you choose to completely disconnect from the network, you will still very likely continue to draw electricity supplies from the network and the above arrangement will continue. However, it is possible that your DG output at any instant might exceed your own electricity needs at that same instant. In this case, electricity in excess of your immediate needs will flow back into the network, since it cannot be stored in your premise’s wiring system. Commercially, you have become a wholesale, network-connected generator and the retailer is your customer for your excess electricity. To set this up so you get paid or credited for your electricity sales, you will need to enter into a separate agreement with your retailer before switching on your DG system. You’ll be very interested in the export register quantities, as this is the measurement by which you will get paid by or credited from the retailer for your excess generation. |
1. This is the most common commercial arrangement that distributors have in NZ for charging for use of their networks. Confusingly for consumers, there are other possibilities. The details of the commercial arrangements between distributors and retailers have an important bearing on the usage of metered data where DG is installed at a premise.
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DG Metering Guide