Options for expanding the voltage range
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34. As discussed on the previous page, expanding the regulated supply voltage range may be a cost-effective option to allow networks to host more distributed energy resources, if appliances sold in New Zealand can tolerate the change.
35. Broadly there are 2 options under consideration for expanding the supply voltage range:
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Option 1: Expand the range to ±10%, aligning it with the range in regulated appliance standards and with the supply voltage range in Europe.
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Option 2: Expand the upper limit to +10% and leave the lower limit at -6%, aligning it with the supply voltage range in Australia.
36. In principle, Option 1 might be expected to have greater benefits because it is more likely to avoid or reduce any voltage constraints at both ends of the range.
37. However, in practice Option 2 may have similar voltage management benefits as Option 1, thermal rather than voltage constraints on transformers dominating EV hosting capacity, as discussed above.
38. Option 2 may also offer lower risks to appliances than Option 1. While recent appliances are likely to have been designed for 230 Volts ±10%, in line with international standards, older appliances in New Zealand are more likely to have been designed to match Australian voltage ranges. Given Australia historically had a higher nominal voltage of 240 Volts and still remains a lower limit of -6% (but +10%) it is possible older appliances may have less tolerance for lower voltages.
39. Also, the technologies that could cause undervoltage (e.g. EVs) at times of peak demand are more likely able to be controlled by equipment (e.g. smart chargers) that can help manage their impact on the network. Such demand management can, in principle, be undertaken in a way that does not reduce the value to the consumer (e.g. an EV can still receive a full charge overnight, even if controlled to charge outside of peak times). Solar PV, in contrast, cannot readily be managed without reducing value, because output is dependent on sunshine hours which cannot be managed.