NIPSCO EDG Billing: What Inflow, Outflow and Instantaneous Netting Mean

If NIPSCO serves your home in northern Indiana and you install solar today, your bill will not look like the “spin the meter backward” net metering your neighbors may describe. New systems are credited under NIPSCO’s Excess Distributed Generation rider, and the bill is built from two separate meter readings rather than one net number. Understanding those two readings is the fastest way to judge whether a savings estimate in a proposal is realistic.

Which NIPSCO program applies to a new rooftop system

NIPSCO lists three customer generation programs, and only one is open to a typical new residential system:

• Net Metering: NIPSCO’s net metering page marks the program “closed to new applications.”
• Feed-in Tariff: NIPSCO’s feed-in tariff page states that “all programs are currently closed to new applicants.” Older articles that describe the feed-in tariff as an option for new projects are out of date.
• Excess Distributed Generation (EDG): described on NIPSCO’s EDG tariff page as the program that lets you “generate your own electricity from renewable energy to offset your individual usage each month.”

The legal framework behind that shift is Indiana Code chapter 8-1-40, available on the Indiana General Assembly’s code site. Our overview of Indiana net metering and EDG covers how the transition worked across the state’s utilities. This page stays on one narrow question: what NIPSCO’s EDG rider does to your monthly bill.

Inflow and outflow: the two numbers on an EDG bill

NIPSCO’s Rider 689, Excess Distributed Generation, defines two separately measured quantities:

• Inflow: “the separate meter channel measurement of the electricity being used by the Customer, net of the electricity being produced by the Customer.” In plain terms, the energy you draw from the grid when your panels are not covering the house.
• Outflow: “the separate meter channel measurement of electricity being produced by Customer above the electricity being used by Customer.” The energy your system pushes out to the grid when it is producing more than the house is using.

The rider requires a meter that can measure the two separately, and states that if your existing meter cannot, NIPSCO “will install and maintain, at Company’s expense, a meter to meet the requirements of this Rider.”

What “instantaneous” netting means in practice

Rider 689 adopts the statutory definition of excess distributed generation from Ind. Code § 8-1-40-5: the difference between the electricity the utility supplies to you and the electricity you supply back, “as measured by the Customer’s meter on an instantaneous basis.”

The words “on an instantaneous basis” are the whole story. The meter does not wait until the end of the month and subtract one total from the other. At any given moment, energy is flowing either into the house or out of it, and the meter records it in the inflow or outflow channel accordingly. Over the month, both channels add up independently.

Under the older monthly net metering approach, a kWh exported at noon could cancel out a kWh imported in the evening at full value. Under EDG, those are two different transactions priced two different ways.

How the monthly bill is calculated

Rider 689 lays out the billing steps directly:

1. During the billing cycle, NIPSCO “will capture the total kWh of Inflow and the total kWh of Outflow.”
2. Inflow kWh are billed under your standard rate schedule, “with all applicable rates and charges.”
3. Outflow kWh are “multiplied by the Marginal DG Price to determine the DG Billing Credit.”
4. You are always billed at least the monthly Minimum Charge in your rate schedule. Credit beyond what is needed to bring the bill down to that minimum is “accumulated in a DG Billing Credit Balance for use in a subsequent period.”
5. When you stop receiving service at the premises, any remaining balance “will be forfeited by the Customer and passed back to Company’s other customers through the Fuel Cost Adjustment.”

The Marginal DG Price: what it is and what it is now

The rider defines the Marginal DG Price as “the average hourly real-time price of energy paid by the Company in the MISO market at the NIPS.NIPS commercial pricing node during the most recent calendar year, multiplied by one and twenty-five hundredths (1.25),” and says it “shall be updated at least annually.”

The billing sheet of Rider 689 with an effective date of April 1, 2026 sets the Marginal DG Price at $0.049685 per kWh for all Outflow. Because the price follows the prior year’s wholesale market, it will move. Check the current rider before relying on that figure in any long-range estimate.

The practical takeaway: inflow is priced at your full rate schedule, outflow is credited at a wholesale-based price. The more of your own production you use at the moment it is generated, the less of it lands in the lower-valued outflow channel.

Reading a proposal with two registers in mind

A savings estimate for a NIPSCO address should be able to answer these questions clearly:

• How much of the projected production is expected to be used in the house, and how much exported as outflow?
• Which Marginal DG Price was applied to outflow, and from which version of Rider 689?
• Does the projection assume the Marginal DG Price stays flat for decades, or change?
• Would shifting large loads to daylight hours, or adding storage, change the outflow share, and by how much in the installer’s own model?
• Has the estimate been checked against your actual interval usage data rather than a monthly total?

A proposal that treats every kWh produced as worth your full retail rate is describing net metering, which is not the program a new NIPSCO system joins. Our full list of questions to ask a solar installer in Indiana covers the rest of the contract.

Interconnection steps NIPSCO lists for EDG

NIPSCO’s EDG page describes a three-step process: submit an interconnection application, wait for a technical review, then sign the applicable agreements before construction. It states that there is no application fee for Level 1 applications, which it lists as 25 kW and below, and that a new meter is installed once installation is complete. Rider 689 also requires a written contract with an initial term of not less than one contract year. Our walkthrough of how a residential solar installation proceeds shows where the utility step fits alongside permits and inspection.

Common questions

Does NIPSCO still do net metering for new solar?

No. NIPSCO’s net metering page says the program is closed to new applications, and Rider 689 is the rider for customers who are not eligible for net metering.

How much does NIPSCO credit for excess solar?

Outflow is credited at the Marginal DG Price in Rider 689, which the sheet effective April 1, 2026 sets at $0.049685 per kWh. The price is updated at least annually.

Can I still sign up for the NIPSCO feed-in tariff?

According to NIPSCO’s feed-in tariff page, all feed-in tariff programs are currently closed to new applicants.

What happens to my DG credits if I move?

Under Rider 689, a remaining DG Billing Credit Balance is forfeited when you no longer receive service at the premises and is passed back to other customers through the Fuel Cost Adjustment.

Where this fits

The two-register bill is the main reason system size and design matter more in northern Indiana than a simple payback chart suggests. Every NIPSCO customer enrolled in EDG is billed under the same rider, and our page on what solar costs Indiana homeowners is where the installed price side of the decision belongs.

When you want to see which participating providers cover your address, you can see what options are available for your home. Matching depends on service area, availability varies, and you decide whether to move forward from there.