An integrated resource plan (IRP) is a utility’s long-range roadmap for how it will meet future electricity demand, and it is one of the earliest public signals of what that utility will procure next.
If you want to understand where solar, storage, and all-source RFPs come from, and see them coming before they are released, this guide will help.
Let’s dive in.
Key Takeaways
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- An integrated resource plan is a long-range plan, typically 10 to 25 years, that shows how a utility intends to serve customer demand at the lowest reasonable cost and risk while factoring in state clean energy goals.
- State policy, such as clean energy standards in California, New York, and Illinois, for example, sets the boundaries every IRP must work within.
- Most utilities update their IRP every 2 to 5 years, and some now refresh their plans annually.
- Load forecasts (data centers, EV adoption, population growth), cost forecasts, and scenario analysis drive which resources a utility selects.
- The resource additions and retirements in an IRP are a strong leading indicator of the RFPs a utility will issue in the following one to three years.
What Is an Integrated Resource Plan?
An integrated resource plan (IRP) is a long-range plan, typically covering 10 to 25 years (most often 15 to 20), that a utility prepares to show how it will reliably meet customer demand at the lowest reasonable cost and risk while factoring in state clean energy goals. It compares supply-side resources (solar, wind, storage, natural gas, nuclear, hydro, market purchases) and demand-side resources (energy efficiency, demand response, distributed energy).
IRPs are most common among vertically integrated investor-owned utilities regulated by a state Public Utility Commission (PUC). Many generation and transmission co-operatives, municipal utilities, and community choice aggregators might also prepare them because state law requires it.
An IRP is a plan, not a purchase order. It does, however, set the direction for what the utility will procure, and in many states it must be acknowledged or approved before major resource acquisitions move forward.
Why Integrated Resource Plans Matter to Developers
Most developers and EPCs first hear about a utility’s needs when an RFP is released. By then, the timeline to prepare a competitive bid is often short. The integrated resource plan usually tells the same story months or even years earlier.
Reading IRPs can help your team:
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- See demand before it becomes an RFP. The preferred portfolio shows how many MW of solar, storage, wind, or firm capacity the utility expects to add, and when.
- Prioritize where to develop. Utilities with large near-term needs and supportive policy are where early-stage projects are most likely to find a buyer.
- Shape the outcome. Developers can participate in the stakeholder process, comment on cost assumptions, and make sure realistic project costs are reflected in the plan.
- Prepare better bids. Knowing the utility’s assumed costs, COD needs, and preferred contract structures helps you position your project when the solicitation arrives.
State Clean Energy Policies That Shape an IRP
State policy sets the boundaries for every integrated resource plan. A utility can only choose a least-cost portfolio from options that comply with its state’s renewable portfolio standard (RPS), clean energy standard, or carbon reduction target. According to the Clean Energy States Alliance, 24 states plus Washington, DC and Puerto Rico have 100% clean energy goals. For example:
| State | Clean energy policy | How it shows up in planning |
|---|---|---|
| California | SB 100: 100% carbon-free electricity by 2045, with interim RPS steps | Load-serving entities, including CCAs, plan to statewide greenhouse gas targets through the CPUC’s IRP process, which drives large solar, storage, and long-duration storage procurement |
| New York | 2019 climate law (S6599): zero-emissions electricity by 2040 and 70% renewable by 2030; the 2026 state budget revised the law’s economy-wide emissions targets, dropping the 2030 goal and adding a 60% reduction target for 2040 | Much of the procurement is run by NYSERDA, while state grid and resource adequacy planning fills the IRP role |
| Illinois | Climate and Equitable Jobs Act (2021): 100% clean energy by 2050, with 40% by 2030 and 50% by 2040 | Most of the state is restructured, so the Illinois Power Agency runs renewable procurement plans |
| Missouri | Renewable Energy Standard (Prop C, 2008): 15% of retail sales from renewables since 2021, with at least 2% of that requirement from solar | Without a 100% mandate, IRPs from Ameren Missouri and Evergy are driven mostly by coal retirements, load growth, and economics |
| Texas | Original RPS goal of 10,000 MW of renewables by 2025, surpassed in 2009, about 15 years early | Most of Texas is in the competitive ERCOT market, where utilities don’t file IRPs; utilities outside ERCOT, such as SPS, SWEPCO, El Paso Electric, and Entergy Texas, still do |
The strength and timing of a state’s policy is often a good predictor of how much solar, wind, and storage appears in its utilities’ preferred portfolios.
How Often Are Integrated Resource Plans Updated?
Most utilities update their integrated resource plan every 2 to 5 years, depending on state rules. Many also file an interim update between full plans to refresh load forecasts, prices, and the near-term action plan.
| State | Planning horizon | Filing frequency |
|---|---|---|
| Oregon and Utah (PacifiCorp) | 20 years | Every 2 years (odd years), with an update in even years |
| Minnesota | 15 years | Every 2 years |
| South Dakota | 10 years | Every 2 years |
| Indiana | 20 years | Every 3 years, staggered by utility |
| Kentucky | 15 years | Every 3 years |
| Missouri | 20 years | Every 3 years |
| Nebraska | 20 years | Every 3 years |
| Iowa | 20 years | Every 5 years |
| Michigan | Multiple horizons | Every 5 years |
Sources: Midwest Energy Efficiency Alliance, PacifiCorp
Knowing when a utility’s next IRP is due, and when its stakeholder meetings begin, gives you a reasonable sense of when its next procurement is likely to follow.
The Forecasts Behind an Integrated Resource Plan
An IRP is only as reliable as its forecasts. The two that matter most are how much electricity customers will need and what each resource option will cost.
Load Forecast
The load forecast projects peak demand (MW) and annual energy (MWh) across the planning horizon. Today’s biggest drivers include:
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- Data centers: AI and cloud data centers are the largest recent change in many utility forecasts. A single campus can add hundreds of MW – even GW, so many utilities now model large loads separately and weight them by likelihood.
- Electric vehicle adoption: EV adoption curves estimate how quickly vehicles electrify and when they charge, which affects both total energy and the timing of peaks.
- Population and economic growth: New homes and businesses, industrial reshoring, and building electrification all add load.
- Efficiency and distributed generation: Rooftop solar and efficiency programs reduce the load the utility must serve.
Cost Forecasts
Cost forecasts estimate capital, operating, and fuel costs for each candidate resource over time. Many utilities start from public sources like the NREL Annual Technology Baseline and adjust using recent RFP bids. The long-term decline in solar PV and battery energy storage (BESS) costs is a major reason these resources appear so often in preferred portfolios. Natural gas prices, tax credit eligibility, and tariffs on imported equipment can shift results significantly.
Some IRPs conduct an RFP process to get more realistic market prices for projects to feed back into the IRP modeling.
Scenarios
Because there is a lot of uncertainty, especially over long time horizons, resource planners test the plan across several scenarios: typically a base case plus high and low cases for load, fuel prices, policy, and technology costs. A resource that performs well across most scenarios is considered low-regret. The preferred portfolio is usually the one that balances cost and risk across the full range of futures, not only the base case.
How the Integrated Resource Planning Process Works
A full IRP often takes a year or more from kickoff to a commission decision. The steps are similar in most states:
- Assess the need. Build the load forecast, review existing resources, and identify the capacity and energy gap, including planned retirements.
- Define resource options. List candidate supply-side and demand-side resources with cost and performance assumptions. Some utilities issue a request for information (RFI) or use recent RFP bids to ground these numbers in market prices.
- Model portfolios. Use capacity expansion and production cost models, such as PLEXOS, Aurora, or EnCompass, to select a least-cost resource mix and test it for reliability.
- Run scenarios and sensitivities. Stress test portfolios against high and low cases for load, fuel prices, policy, and costs.
- Gather stakeholder feedback. Customers, consumer advocates, environmental groups, developers, and commission staff review assumptions and request additional cases, often while modeling is underway.
- Select the preferred portfolio and action plan. Choose the portfolio that best balances cost, reliability, and risk, and define the near-term steps for the next 2 to 5 years.
- Regulatory review. File with the state PUC, where intervenors submit testimony and the commission acknowledges, approves, or requests changes.
The level of review varies. Some states formally approve the plan, others acknowledge that it meets planning requirements, and some accept it as filed. An approved IRP usually does not approve specific projects; those typically go through a separate certificate or contract approval proceeding.
How to Read an Integrated Resource Plan
IRPs often run hundreds of pages, with appendices that run longer still. You don’t need to read every page to find what matters. These principles can help you get to the useful parts quickly.
Start With the Action Plan
The action plan is usually only a few pages long and is typically covered in the executive summary. It holds the utility’s specific near-term commitments. This is where you’ll find statements about upcoming solicitations, typically worded along the lines of “issue an all-source RFP for up to 1,500 MW of resources with in-service dates by 2030.”
Look at the Resource Additions by Year
The additions table lists the MW of new solar, wind, storage, gas, and other resources the utility plans to add, year by year. Additions in the first few years are the ones most likely to become RFPs soon. Notice whether the plan names a specific technology (solar, 4-hour storage) or leaves it open (generic capacity). That distinction often hints at whether the next solicitation will be technology-specific or all-source.
Follow the Retirements
Retirement dates for coal and older gas units create the capacity gap that new resources are meant to fill. When a retirement is delayed, related procurement often slips too. When one is accelerated, an RFP tends to follow.
Compare the Resource Mix Over Time
The plan shows the generation mix today and how it changes over the horizon, in MW and percentage of energy by technology. This tells you which technologies the utility expects to rely on and how much room remains for new projects.
Check the Scenarios, Not Just the Base Case
Resources that appear in nearly every scenario are the safest bets. Resources that only appear under high-load or high-gas-price cases may never be procured.
From Integrated Resource Plan to RFP
The IRP identifies the need, and the RFP is how the utility fills it. Once an action plan is acknowledged, many utilities issue a competitive solicitation to test the market against the costs they assumed. In several states, a competitive RFP is expected before a utility can self-build or sign a long-term contract.
The type of RFP usually mirrors how specific the IRP was:
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- Technology-specific needs (a set MW of solar or 4-hour storage) tend to lead to solar RFPs, energy storage RFPs, or paired solar + storage RFPs.
- Generic capacity or reliability needs tend to lead to all-source RFPs, such as the NorthWestern Energy All-Source Capacity RFP, which sought capacity in service by the end of 2029.
- Clean energy compliance needs tend to lead to renewable energy or RE RFPs.
The relationship also runs in reverse. Bid prices from one RFP become cost assumptions in the next IRP, so following both gives a clearer picture of where a utility is heading.
2026 Integrated Resource Plan Examples
The 2026 IRPs filed so far share a common theme: load growth, much of it from data centers, is leading utilities to plan record amounts of solar and storage alongside new gas.
| IRP | Filed | Planned additions | Main driver |
|---|---|---|---|
| Duke Energy Carolinas Resource Plan (NC and SC) | August 2026, PSC of South Carolina | By 2041: 18.5 GW solar, about 13 GW storage, 8.2 GW combined cycle, 5.8 GW combustion turbines, 4.5 GW nuclear, 300 MW onshore wind | Population growth and new large-load service agreements |
| NV Energy 2026 IRP (Nevada) | Spring 2026, PUC of Nevada | Over the next six years: more than 4.3 GW solar, 5.4 GW storage, 180 MW geothermal, and 1.2 GW of new gas turbines | Data centers, projected to grow from 5% of sales today to 64% by 2046 |
| Clean Power Alliance 2026 IRP (California CCA) | August 2026, CPUC | Contracted solar, storage, and geothermal, including a 200 MW solar plus 200 MW 4-hour storage project with a May 2029 COD | California greenhouse gas targets and reliability procurement orders |
Duke Energy Carolinas. Duke describes its dual-state plan as all-of-the-above, yet solar is still the largest single addition through 2041. The plan references active RFPs for solar and solar paired with storage. South Carolina regulators expect to hold a hearing in April 2027 and issue an order by June 2027.
NV Energy. NV Energy calls this the largest renewable and storage expansion in its history, with most new capacity procured through PPAs. To manage uncertainty, the plan includes load forecasts with and without large data center loads.
Clean Power Alliance. California’s community choice aggregators file their own IRPs as part of the CPUC’s statewide planning cycle. CPA’s plan shows how CCAs layer solar, storage, and firm clean resources to meet state requirements, which makes them an active buyer group for developers.
The Future of Integrated Resource Planning
The traditional IRP is changing in two ways: it is becoming more integrated, and it is moving faster.
Fully Integrated Planning
Utilities have historically planned generation in the IRP and planned transmission and distribution in separate processes. That separation is harder to maintain when the best new resources depend on new transmission, and when distributed solar, storage, and EV charging change how the distribution grid operates. Some utilities are moving toward integrated system planning, sometimes called integrated grid planning, which considers generation, transmission, and distribution together. Hawaiian Electric’s Integrated Grid Planning process is an early example. PacifiCorp’s recent IRPs also plan transmission upgrades alongside new resources, because many of its preferred additions depend on that transmission.
Faster Planning Cycles
A 2 to 5 year cycle worked well when load was flat. With large-load requests now arriving month by month, a plan can be out of date before the commission rules on it. Utilities are responding in a few ways:
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- PacifiCorp files a full IRP every two years and an update in the off year. Its 2025 IRP Update, filed March 31, 2026, states the company intends to refresh its action plan at least annually. Western Resource Advocates has observed that in practice this amounts to an annual IRP.
- Utilities like NV Energy now carry multiple load forecasts (base, base plus, and base minus) so the plan can adjust as large-load contracts are signed or fall through.
- Some utilities file amendments or supplemental plans mid-cycle when a major load or retirement changes their needs.
Better tools are likely to accelerate this trend. Faster modeling software, cloud computing, and AI-assisted data preparation can shorten work that once took weeks, making annual or more regular planning more realistic.
For developers, this likely means more frequent and sometimes smaller procurement windows, and a greater benefit to following both IRPs and RFPs closely.
Integrated Resource Plan FAQs
What is the purpose of an integrated resource plan?
The purpose of an integrated resource plan is to identify the mix of supply-side and demand-side resources that will meet a utility’s future electricity needs reliably, at the lowest reasonable cost, and in compliance with state policy.
What is the difference between an IRP and an RFP?
An IRP is a long-range plan that identifies what resources a utility needs. An RFP (request for proposals) is a solicitation the utility issues to buy specific resources, often to fill needs identified in its IRP.
Who approves an integrated resource plan?
For investor-owned utilities, the state Public Utility Commission (PUC) reviews the IRP and approves, acknowledges, or accepts it, depending on the state. Co-ops and municipal utilities usually adopt their IRPs through their own boards or councils.
How long is an IRP planning horizon?
Most IRPs cover 10 to 25 years, most often 15 to 20, with the most detailed analysis and specific commitments focused on the first 5 to 10 years.
Do all utilities file integrated resource plans?
No. IRPs are most common for vertically integrated utilities in regulated states. Utilities in restructured markets such as ERCOT, and in many Northeast states, generally do not file traditional IRPs, although other planning processes often fill a similar role.
What is a preferred portfolio?
The preferred portfolio is the combination of resource additions, retirements, and programs that the utility selects as its best plan after comparing cost and risk across scenarios.
Points Worth Noting
A few final points worth keeping in mind as you follow integrated resource plans.
An IRP is a forecast, not a promise. Plans change between cycles as loads, prices, and policies shift. The value of an IRP comes from following how it changes over time, not from reading one version in isolation.
The best opportunities appear before the RFP. Developers who follow a utility’s planning process understand its needs, timeline, and cost expectations well before the solicitation is released, and they tend to submit stronger bids as a result.
Participation matters. Stakeholder comments from developers help keep cost and availability assumptions realistic. A plan built on accurate market data is better for the utility, its customers, and the projects that ultimately get built.
Following IRPs and RFPs in One Place
IRPs and RFPs are two halves of the same story: one describes what a utility needs, and the other is how it buys it. Energy Adepto currently tracks active solar, storage, all-source, and renewable RFPs from utilities, co-ops, municipal utilities, and CCAs across the U.S. and Canada, with IRP tracking coming soon. If following that full picture would be useful to your team, you’re welcome to check it out on a free 14-day trial.
About the author: Andreas is the founder of Energy Adepto. He previously worked as an energy procurement consultant at Burns & McDonnell (1898 & Co.), managing utility RFP processes across SPP and MISO, and later built software for large utilities.
