On-site (Distributed) Generation

On-site, customer-owned electric generation installations, such as solar, wind, or biomass, have become increasingly popular in Iowa. Many of these facilities are connected to the electric grid, which involves the local utility provider. The Iowa Utilities Board (IUB) has regulatory authority over the investor-owned utilities, but the IUB has limited authority (service, safety, and engineering issues) for the municipal electric and rural electric cooperative utilities in Iowa.

The IUB provides a Consumer Informational Guide for On-site (Distributed) Generation to help residential or small businesses that are considering installing electric generation on their property. The guide also includes links to additional information that may be useful to make an informed decision about installing on-site generation. The Iowa Energy Center developed a Solar PV Energy Guide to help residential or small businesses that are specifically interested in solar installations.

Interconnection

The IUB has rules related to interconnection of on-site generation facilities. The IUB's standards for interconnection, safety and operating reliability are found in 199 IAC chapter 15 and are applicable to all utilities. 

Additionally, the IUB's rules for Electric Interconnection of Distributed Generation facilities are found in 199 IAC chapter 45 and are applicable to those utilities subject to rate regulation by the IUB (such as MidAmerican Energy Company and Interstate Power and Light Company). 

The chapter 45 rules previously contained standard forms and agreements used by applicants in the interconnection application process. These forms and agreements have been removed from the rules but have been updated to allow the applicant to fill in the forms electronically. Following are links to the interconnection forms and agreements:

​Net Metering

Net metering means using a single meter to monitor the net amount of electricity delivered to and exported by an eligible distributed generation facility. The electricity generated by the distributed generation customer offsets electricity that would otherwise be purchased by a distributed generation customer from the electric utility. The IUB's rules for net metering are found in 199 IAC 15.11(5)

On March 12, 2020, Gov. Kim Reynolds signed Senate File 583 (Iowa Code § 476.49), which required Interstate Power and Light Company and MidAmerican Energy Company to file new net metering tariffs utilizing either the net billing or inflow-outflow method.

Net billing is a billing method in which the distributed generation customer pays all applicable charges, including applicable riders approved by the IUB for the electricity the utility delivers to the customer, and is credited in kilowatt-hours for energy exported to the electric utility during the billing period. The distributed generation customer may use the kilowatt-hour credits to offset kilowatt-hours in future billing periods.

Inflow-outflow is a billing method in which the distributed generation customer pays all applicable charges, including applicable riders approved by the IUB for the electricity the utility delivers to the customer, and is credited in dollars at the outflow purchase rate for energy exported to the utility during the billing period. The distributed generation customer may use the dollar credits to offset any applicable volumetric charges billed on a kilowatt-hour basis in future billing periods.

The following tariffs have been approved by the IUB:

MidAmerican Energy Company
Docket No. TF-2020-0235, Rate IO – Inflow/Outflow Billing of Eligible Distributed Generation Facilities tariff (approved November 24, 2020)

Interstate Power and Light Company
Docket No. TF-2020-0237, Inflow-Outflow DG Billing (Rate Code: IO) tariff (approved December 30, 2020)
Docket No. TF-2020-0238, Revisions to Net Metering Pilot – Renewable Energy Facilities (Rate Code NM) tariff (approved December 30, 2020)

Distributed Generation Penetration Percentage
Iowa Code § 476.49 became effective July 1, 2020. Iowa Code § 476.49(2) directed the IUB to “collect data on the nameplate capacity of eligible distributed generation facilities, calculate the statewide distributed generation penetration percentage, and publish the data and penetration rate on an annual basis" on the IUB's website.

Below is the statewide distributed generation penetration percentage and the penetration percentages reported by MidAmerican Energy Company and Interstate Power and Light Company on April 29, 2022, in Docket Nos. TF-2020-0235 and TF-2020-0237, respectively.

 2021 Distributed Generation Penetration Percentage

 

MidAmerican

IPL

Statewide

Installed Distributed Generation Facilities (MW)

29.2661]

113.49[2]

142.756

2020 Peak Demand (MW)

4,789[3]

2,892[4]

7,491[5]

 

 

 

 

Penetration Rate

0.61%

3.92%

1.91%

According to Iowa Code § 476.49(4), the IUB is required to initiate a proceeding to develop a value of solar methodology and rate for eligible distributed generation facilities when the statewide distributed generation penetration rate is equal to five percent or if the IUB is petitioned by an electric utility after July 1, 2027, whichever is earlier.


[1] Net metering total from the “Alternative Energy Production Facility Report 2020” filed in Docket No. IAC-2022-1511 on March 30, 2022.

[2] IPL’s distributed generation facility total is from IPL’s records and includes facilities enrolled in its AEP Net Metering and Net Metering Pilot tariffs. 

[3] MidAmerican’s Iowa annual peak for 2021 as reported in the “2022 AE Allocator Calculation” report in Docket No. TF-2022-0009 on February 15, 2022.

[4] IPL’s Iowa annual peak demand from FERC Form 1, page 401b.

[5] The IUB is using the sum of MidAmerican’s and IPL’s peak demand as a reasonable estimate for the statewide demand.  The IUB reviewed information filed in MidAmerican’s and IPL’s FERC Form 1, page 401b, to ensure that this peak demand value is a reasonable estimate.  Currently there is nothing filed with the IUB that allows the IUB to determine a statewide coincident peak demand.

Printed from the website on February 05, 2023 at 2:49pm.