If you’ve been following Illinois solar development, you’ve probably noticed a frustrating pattern: a project gets announced, secures land, files paperwork, and may even receive early “approval” milestones—yet it still doesn’t get built for years. The culprit is often the same bottleneck across the Midwest and much of the U.S.: the generator interconnection queue.
Interconnection is the process of getting permission—and a technical roadmap—to connect a new power plant (including solar) to the electric grid. In Illinois, many projects interconnect through MISO (covering much of the state) while others fall under PJM territory (parts of northern/eastern Illinois). When either region’s queue jams up, “approved” projects can stall in place even if the developer is ready to build.
Here’s what’s really happening, why the backlog persists, and what reforms are changing the timeline.
What “interconnection” actually means
Interconnection isn’t just “plugging in.” Grid operators must study whether adding a new solar plant will overload transmission lines, substations, or protection systems—and if it will, they determine network upgrades needed to keep the grid safe and reliable.
This happens through formal procedures and agreements overseen by federal rules. In 2023, FERC issued Order No. 2023, a major reform aimed at reducing queue backlogs and improving study speed and certainty.
Why “approved” projects still get stuck
A project can feel “approved” at the local level (zoning, special use permits, land leases) or even show as “active” in a queue—yet still be stalled because interconnection progress is gated by studies, upgrades, and timelines controlled by the grid operator.
1) There are too many projects in line—and not enough transmission capacity
Across the country, queues filled up with enormous volumes of solar, wind, and storage proposals—often far exceeding what the existing grid can absorb without upgrades. Reuters has described the national queue scale and how long studies have taken on average in recent years.
2) The study process was historically slow and sequential
Older processes often studied projects one-by-one. When projects entered in huge volumes, the system broke. Order No. 2023 pushes the industry toward cluster studies (studying groups together) to speed things up and allocate upgrade costs more sensibly.
3) “Speculative” projects clogged the queue
For years, developers could enter queues with relatively low commitment. Many projects weren’t truly financeable or shovel-ready, but they still consumed study bandwidth. Reforms increasingly require milestones and deposits so only serious projects stay in line. PJM explicitly highlights milestones/deposits as part of its reformed approach.
4) Network upgrades can be expensive—and take years
Even after studies, the project may be assigned upgrades like substation rebuilds, reconductoring, or new lines. Those upgrades can:
- cost far more than expected,
- require separate permitting,
- face supply-chain and construction constraints,
- and be dependent on other projects not withdrawing.
This is where many “approved” projects stall: they’re technically feasible, but the upgrade price tag or timeline breaks the business case.
5) Withdrawals create a domino effect
When projects drop out, it can force re-studies for the remaining ones, delaying everyone. MISO has explicitly noted how withdrawals and queue volume make studies slower and less certain, motivating queue reform efforts.
Illinois-specific reality: MISO vs. PJM queues
Illinois is impacted by two major queue ecosystems:
MISO: a multi-year backlog and ongoing reforms
MISO has acknowledged the need for queue reforms to reduce volume and speed studies.
It also publicly posts generator interconnection cycle schedules and explains elements like its Definitive Planning Phase (DPP) cycles.
A U.S. DOE policy note on MISO queue reform highlighted how a meaningful share of active projects had not even started studies at that time—illustrating how projects can sit in limbo for long periods.
MISO has also pursued targeted solutions, including a joint portfolio effort with SPP along a constrained seam (JTIQ) and other planning initiatives referenced in its interconnection materials.
And Reuters reported MISO launched an expedited process for a limited set of projects intended to be operational within a defined window—another sign that queue timelines were becoming incompatible with rising demand.
PJM: reforms are clearing a transition backlog, but timelines are still real
PJM’s public updates describe progress and remaining work in its transition queue, along with expectations that the reformed process targets one- to two-year turnaround times going forward (after backlog processing).
Outside analysts and industry groups have argued PJM’s backlog materially slowed renewable and storage deployment in its footprint, reinforcing how queue delays translate into real-world “stalled” projects.
The core issue: interconnection became the new “permit”
A decade ago, the hardest part of building solar was often:
- site control,
- local permitting,
- financing,
- or panel costs.
Now, for many utility-scale projects, interconnection is the critical path—and it can be longer and less predictable than all other steps combined.
That’s why you’ll see projects described as “approved” locally, but effectively frozen until:
- studies are complete,
- upgrade scope/cost is known,
- and an interconnection agreement can be finalized.
What reforms are changing (and why it still takes time)
Cluster studies + standardized timelines
FERC Order No. 2023 requires major procedural reforms, including cluster study approaches and other tools intended to speed interconnection and improve certainty.
“More skin in the game”
Grid operators are increasingly using milestones and deposits to reduce speculative requests and keep queues manageable. PJM has been explicit about this structure in describing its new approach.
Better tools and automation
PJM has discussed using new tools (including AI-enhanced planning tools via partnerships) to reduce connection times, and Reuters has reported on broader efforts to modernize studies with software and automation.
Still, reforms don’t instantly create new transmission lines or transformer capacity. Queue reform helps process projects faster—but the grid still needs physical expansion.
What developers and communities can do right now
If you’re tracking Illinois solar proposals, here are practical “tell me if it’s real” indicators:
- Interconnection status: Is the project still early in studies, or does it have a clear path to an executed interconnection agreement?
- Upgrade exposure: Has the developer disclosed likely network upgrade scope/cost?
- Storage pairing: Projects with storage can sometimes improve deliverability/value (though they still face queue realities).
- Land + local permits vs. grid readiness: Local approvals are necessary—but not sufficient.
- Transmission awareness: Projects near strong substations/lines can still get stuck if the broader system is constrained.
Bottom line
So many Illinois solar projects are “stalled” because the grid’s interconnection pipeline became overwhelmed—by volume, by constrained transmission, by expensive upgrades, and by legacy study methods. Reforms from FERC and the grid operators are real and measurable, especially in PJM and MISO’s evolving processes, but turning “approved on paper” into “energized on the grid” still depends on studies, upgrades, and—most importantly—more transmission capacity.
