What is the difference between Interconnection Service (e.g.,NRIS) and Transmission Service (e.g.,NITS)?
Understand that Interconnection Service does not provide Transmission Service.
One of the most popular blogs I had ever written for Renewable Energy World was called “Network Resource Interconnection Service is a better choice than ERIS for small-scale renewable developers”. Even though I wrote about this topic in the summer of 2020, it is still relevant 3 years later.
Generators request to “interconnect” to the transmission system. Hence these requests enter the Generator Interconnection Queue (GIQ). These generator requests are studied. They are studied to assess if they have an impact on the transmission system. Most likely they do have an impact because there are so many generators seeking access to the same transmission system.
Let’s assume the studies are done. The contract that binds the generators to the transmission system is called Generator Interconnection Agreement (GIA). Based on what the generator has elected to pay (yes, they have a choice!), these generators receive a Network Resource Interconnection Service (NRIS) or an Energy Resource Interconnection Service (ERIS).
When a generator pays for upgrades to the transmission system to accommodate the transmission flows that are a result of the new generator, then, the generator receives the NRIS. NRIS is firm compared to an ERIS which is non-firm.
What is firm versus non-firm Interconnection Service?
A firm Interconnection Service like NRIS means your generator output will not be curtailed unless there is an emergency event. A non-firm Interconnection Service like ERIS means your generator output could be curtailed first to accommodate firm transactions. That is the key difference between NRIS and ERIS.
Why is this NRIS versus ERIS relevant?
When you are filling out the generator interconnection application, you are required to fill out what level of Interconnection Service are you seeking. When you are seeking NRIS, if you don’t want to pay for full Interconnection Service, you can elect to a percentage of the total upgrade costs and receive NRIS up to a certain MW output level. The remaining MW output can be ERIS.
Can I switch from NRIS to ERIS and vice versa?
Yes, you can switch from NRIS to ERIS but you cannot switch from ERIS to NRIS in between an interconnection study. You will have to go back to the queue if you are switching from non-firm ERIS to firm NRIS.
So, what is Network Integration Transmission Service (NITS)? How is it different than NRIS?
A generator needs to reserve its spot on the Transmission System. That reservation system is called NITS. At MISO, you can do Point to Point transmission service requests or you can do NITS.
References
MISO Generation Interconnection Business Practices Manual BPM-015-r25
MISO Module B Business Practices Manual BPM-013-r19