What is in the NEM3 / Net Billing Tariff:
While NEM 3.0 is not finalized, Aurora is closely monitoring the proceedings and this guide is based on the latest structures to this plan proposed on December 13th, 2021. The below guidelines would affect any interconnection applications submitted after May 27th, 2022 if the current proposal is passed.
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Residential customers are required to enroll in Electrification Rates. The currently allowed rates are:
- PG&E: EV2-A
- SCE: TOU-D-PRIME
- SDG&E: EV-TOU-5
- We expect more rates to be allowed by the CPUC in the future
- Commercial and CARE customers can keep any TOU rate.
What has changed with NEM 3.0 and how to model it with Aurora
Overview
- Behind-the-meter operation is the same as normal. However, excess energy is no longer compensated at retail rate (less non-bypassable charges); instead, the compensation rate is based on the most recent Avoided Cost Calculator and has a different rate for each hour.
- Aurora does not currently support export rates that vary hourly. However, we find that you can approximate the ACC export rates using a percentage reduction.
- For residential customers:
- PG&E: Export Rate with an 80% reduction
- SCE: Export Rate with a 75% reduction
- SDG&E: Export Rate with an 80% reduction.
- For residential customers:
- Aurora does not currently support export rates that vary hourly. However, we find that you can approximate the ACC export rates using a percentage reduction.
CARE rates still need this reduction, but should be closer to 65% since the CARE volumetric rates are roughly half of non-CARE volumetric rates.
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- The export rate is only fixed for 5 years, however, there’s no strong indication that future iterations of the ACC will be better or worse for solar.
- It is important to note that this is an approximation as an exact rate would be extremely difficult to set up, you would need to create a distinct period for each month-hour, for weekdays and weekends - a total of 576 individual period types.
- There is now a fixed “Grid Participation Charge”, at $8/kW CEC-AC/month.
- You will have to add this manually to the fixed charge section.
- The CEC AC rating is the product of the module’s PTC rating and the inverter efficiency. You can approximate this as 90% of the STC rating, so the monthly fee is approximated as $7.20/kW STC per month.
- Minimum charges are removed and can be set to $0/month.
- CARE rates ignore the Grid Participation Charge.
- True-up period is still annual, and the true-up month is based on the expected PTO of the system.
- Market Transition Credit:
- There is a $/kW CEC-AC/month credit that lasts for 10 years, and you can approximate this as a PBI in the incentives section.
Suggested Approximation for Residential Rates
Follow steps 1 - 6 to set up an approximation for non-CARE residential customers. For CARE customers, you can follow these steps but omit the fixed charge and set the percentage reduction to half of the non-CARE reduction (eg 40% instead of 80%). For Commercial customers, you will have to determine an approximate export reduction - a rule-of-thumb is to divide 5 by the average $/kWh rate.
1. In the Aurora utility database, create a duplicate of EV2-A (NEM3), TOU-D-PRIME (NEM3), or EV-TOU-5 (NEM3) template rate.
Important Note: In order for the residential rates shown in the Aurora database to appear as available for use on your projects, a custom rate must be created.
2. Pick a system size - in this example, a 6 kW STC system. To model the Grid Participation Charge, set the Fixed Charge to be the system size multiplied by $7.20 - in this case, 6 kW * $7.20 = $43.20 per month The $7.20 comes from the $8 per month per kW CEC-AC and an assumption that 1 kW STC is about 0.9 kW CEC-AC Note that TOU-D-PRIME has a $12 fixed charge and EV-TOU-5 has a $16 fixed charge on top of the GPC.
3. Set the Minimum Bill to $0/month.
4. Configure the Export Rate to be “Retail rate with Percent Reduction” and use 80% for PG&E or SDG&E; 75% for SCE
Since CARE rates do not have the Grid Participation Charge, you can skip step 5 for CARE rates.
5. Repeat steps 1-4 for a variety of your system sizes. For simplicity, we suggest stepping by 2 kW over your typical system sizes - eg 4 kW, 6 kW, 8 kW, 10 kW.
Market Transition Credits
PG&E and SCE customers receive a 10-year Market Transition Credit. The best way to approximate this is using a Performance-Based Incentive (PBI). To model the PBI:
- Navigate to Incentives section of your Database.
- Create a 10-year PBI.
- More information on custom incentives can be found here - Incentives
- Set the escalation rate to be equal to your standard module degradation rate so that the value stays flat for 10 years.
- Use this table to set a PBI rate. These value translations assume a yield of 1400 kWh/kW STC
- for PG&E and 1,500 kWh/kW STC for SCE.
Utility | PG&E non-CARE | PG&E | SCE non-CARE | SCE Care |
MTC | $1.62/kW-CEC | $4.36/kW-CEC | $3.59/kW-CEC | $5.25/kW-CEC |
PBI Value | $0.0125/kWh | $0.0336/kWh | $0.0258/kWh | $0.0378/kWh |