account the need to preserve NEM integrity and storage sizing limits. IREC asks the Commission to limit the size of storage systems relative to NEMgenerators based on the amount of energy stored in the battery relative to the daily peak output NEM-generator. They provide an example of a 4 kW PV system that has a maximum daily output of 50 kWh (kilowatt hour) and suggest that the sizing requirement be based on this kWh quantity plus expected losses, for a maximum size of 58 kWh. IREC contends this approach would be easier to implement and more equitable. PG&E and SDG&E support sizing limitations. PG&E suggests that the Commission modify the size capacity limits proposed and instead limit storage system size based on the lesser of the NEM-eligible generator capacity or the site customer maximum demand. SDG&E also suggested the Commission modify the size capacity limits proposed. SDG&E proposed that the storage system be sized to the AC nameplate of the NEM-generator’s inverter and from an energy perspective that the storage device should be no larger than the energy production of the NEM-generator on a single day. Outback suggested a sizing capacity limit of not more than 12:1 in terms of maximum discharge power to maximum renewable generator power. Outback contends this ratio would be sufficient to allow the generator to produce enough energy in a single day to match typical energy needs and round trip efficiency losses while also meeting the instantaneous power needs of the local loads being leveled or reduced. ORA suggested that the sizing limit be consistent with current SGIP requirements. Discussion The goal of this requirement is to set sizing requirements that ensure that the NEM-paired storage system is sized in such a way that it primarily functions to augment the value of the NEM-generator. With that in mind, IREC and SDG&E’s
account the need to preserve NEM integrity and storage sizing limits. IREC asks the Commission to limit the size of storage systems relative to NEMgenerators based on the amount of energy stored in the battery relative to the daily peak output NEM-generator. They provide an example of a 4 kW PV system that has a maximum daily output of 50 kWh (kilowatt hour) and suggest that the sizing requirement be based on this kWh quantity plus expected losses, for a maximum size of 58 kWh. IREC contends this approach would be easier to implement and more equitable. PG&E and SDG&E support sizing limitations. PG&E suggests that the Commission modify the size capacity limits proposed and instead limit storage system size based on the lesser of the NEM-eligible generator capacity or the customer maximum demand. SDG&E also suggested the Commission modify the size capacity limits proposed. SDG&E proposed that the storage system be sized to the AC nameplate of the NEM-generator’s inverter and from an energy perspective that the storage device should be no larger than the energy production of the NEM-generator on a single day. Outback suggested a sizing capacity limit of not more than 12:1 in terms of maximum discharge power to maximum renewable generator power. Outback contends this ratio would be sufficient to allow the generator to produce enough energy in a single day to match typical energy needs and round trip efficiency losses while also meeting the instantaneous power needs of the local loads being leveled or reduced. ORA suggested that the sizing limit be consistent with current SGIP requirements. Discussion The goal of this requirement is to set sizing requirements that ensure that the NEM-paired storage system is sized in such a way that it primarily functions to augment the value of the NEM-generator. With that in mind, IREC and SDG&E’s site
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