It is now well understood that MISO is conducting a DER Affected Systems Study (AFS) process for all distribution-connected DERs because FERC approved MISO’s Order 2222 filing. MISO started the DER AFS process even before the FERC approval, but FERC approval of MISO’s process adds credibility and certainty to DER providers, as this DER AFS process is now documented in MISO’s tariff.
Some Community Solar Garden (CSG) developers were caught by surprise due to this MISO process because Xcel Energy has been conducting its assessment of DER interconnections. Now, with dual studies – one conducted by Xcel and another conducted by MISO, the developers and clean energy organizations (CEO) have complained to the Minnesota Public Utilities Commission (PUC) that Xcel’s transmission system impact study process duplicates MISO’s DER AFS process. It remains to be seen which way the Minnesota PUC is going to go with this timely topic because duplicate studies are dragging the timeline to interconnect CSGs in Minnesota, which could have a ripple effect on all DER interconnections at MISO.
Xcel and the CEO differ in eight main categories.
1. Definition of Transmission Provider in Minnesota Distributed Energy Resource Interconnection Process (MN DIP): Xcel claims it meets MN DIP definitions of both Transmission Owner and Transmission Provider and may thus perform internal transmission studies (ITS). The CEO argues Xcel is only the Area Electric Power System (EPS) Operator under MN DIP and cannot conduct transmission studies unless designated by MISO.
This is a key contention for the CEO because Xcel can come up with distribution system upgrades from its studies, in addition to MISO showing a need for transmission system upgrades to accommodate the same DER interconnection. That would be a double whammy for CSG developers, who are not seeking to become a MISO market participant.
Before the FERC Order 2222 compliance discussions kicked off at MISO, MISO took a lighter-touch approach to distribution-connected interconnections. In the past, MISO allowed the transmission owner to deal with the distribution interconnection received by the distribution utility. Anticipating a lot of DER interconnections, convinced in part by Xcel’s arguments during the early stages of 2222 compliance, MISO instituted this new DER AFS process.
2. Legal and Regulatory Authority: Xcel cites the MN DIP glossary and development history and claims that the MN DIP does not restrict the Transmission Provider role to MISO. The CEO asserts the MN DIP process requires Commission approval for any change, including ITS; failure to do so violates Minn. Stat. §216B.03.
In Minnesota, which is under a wholesale market operator, the term Transmission Provider for a non-lawyer like me refers to MISO because MISO provides the transmission for all market participants in a non-discriminatory manner, because transmission owners like Xcel have turned over the functional authority to MISO. That last piece of functional control is codified in the MISO Transmission Owners Agreement.
In return, MISO plans for the regional transmission needs as an RTO. That is the reason MISO puts together a MISO Transmission Expansion Plan (MTEP). Xcel and other transmission owners take transmission projects in that MTEP for state PUCs’ approval for a certificate of need to construct. So, Xcel is a transmission owner and MISO is a transmission provider within Minnesota, which is one interpretation.
But Xcel is stating in this MN PUC proceeding that it is both a transmission owner and a transmission provider. That’s the point of contention for CEOs because if MN PUC deems Xcel is also a transmission provider, then Xcel can conduct its own transmission impact studies like MISO, and that leads to scope, schedule, and budget implications for CSG developers.
3. Duplication of MISO AFS Study: Xcel asserts that ITS applies only where MISO does not perform a study. Xcel uses Daytime Minimum Load, or DML, as the trigger, while MISO uses peak load. Hence, Xcel argues that it is not duplicating the MISO AFS study.
4. Study Triggers (Daytime Minimum Load DML vs. Peak Load): Xcel defends the use of DML as technically sound and needed for safety/reliability. Xcel claims MISO chose peak load “for simplicity,” not because DML is invalid. The CEO argues DML threshold was rejected during the MISO stakeholder process and is ill-suited, especially for DERs without batteries
5. NERC Compliance: Xcel claims NERC FAC-002-4 requires both MISO and Xcel (as Transmission Planners) to conduct studies under different triggers. The CEO questions why MISO isn’t using DML if NERC truly requires it, suggesting Xcel may be overinterpreting NERC rules.
6. Cost and Impact on DER Programs: Xcel argues that ITS protects system reliability and is not duplicative. Xcel also stated that it is willing to improve transparency. The CEO warns that ITS creates major costs and delays, especially harming Low —and Moderate-Income solar (up to 5 MW) and Distributed Solar Energy Standard (DSES) (up to 10 MW) projects.
7. Modification to MN DIP: Xcel claims no modifications are needed to the MN DIP process because ITS is consistent with the current language. The CEO says ITS deviates from MN DIP and should be formally evaluated before implementation.
8. Stakeholder Process and Transparency: Xcel states it is willing to engage in DER workgroup discussions to refine ITS timing or process, and it opposes a stay, citing NERC compliance risk. The CEO requested that MN PUC open a formal investigation and stakeholder process before continuing with ITS because of Xcel’s poor communication and unclear rationale.
