Interconnection queues are more congested than ever, and the path to approval is increasingly opaque. Developers are spending serious money on land control, studies, and legal work, only to hit delays when grid studies surface surprises late in the process. Projects that look viable on paper are stalling at the grid interface. As one power engineering leader put it, “Interconnection has become the new critical stumbling stone in project success.”
Too often, interconnection is treated as a compliance checkbox rather than a design discipline, a costly mindset. Dealing with utilities has become a much more sophisticated process, and understanding their concerns is fundamental for the successful interconnection of large-scale solar projects. The teams that win are reframing interconnection as a strategic engineering aspect that de risks approvals, controls costs, and keeps CODs on track.
Interconnection planning is the proactive evaluation of grid capacity, voltage regulation, stability, and protection coordination early in development, well before a project is “locked in.” It anticipates utility concerns and produces the models and evidence utilities need to approve new distributed energy resources.
Three advanced simulation tools anchor this work:
• PSCAD: Used for electromagnetic transient/dynamic analysis, particularly valuable for inverter based resources. Utilities use PSCAD files to assess how your asset behaves during disturbances and whether it meets stability and ride through expectations.
• PSSE: A steady state power flow and contingency analysis platform widely used at the transmission level. It helps identify thermal and voltage constraints across scenarios.
• ASPEN OneLiner: Focused on protection engineering: short circuit duties, relay coordination, and fault current behavior to ensure your plant integrates safely with existing protection schemes.
Supplying the exact simulations and formats preferred by each utility help you reduce approval uncertainty. Unfortunately, preferences vary by region and utility, so “one size fits all” packages fail more often than not. The result of proficient interconnection planning is improved cost control, since grid limits are discovered early, before equipment is specified and permits are scoped. Also, schedule risk shrinks while you replace trial and error with evidence based design choices.
“As our industry gets bigger and our footprint larger, we’re going to be responsible for more, and utilities are going to study these projects more deeply. That’s inevitable.” - Ben Roeland, Director of Power Engineering at Pure Power.
Utilities are tasked with maintaining grid reliability and safety. Their concerns during interconnection reviews are not arbitrary; they stem from real operational risks and system limitations. Understanding these concerns helps developers align with utility priorities and avoid costly delays.
Top Utility Concerns Include:
• System Stability: Will the new resource stay online and behave predictably during faults or disturbances?
• Voltage Regulation: Will the project cause voltage fluctuations or violate acceptable limits under normal and contingency conditions?
• Thermal Loading: Will the project overload lines, transformers, or other infrastructure?
• Protection Coordination: Will fault currents disrupt existing relay schemes or exceed device ratings?
• Model Fidelity: Are the submitted simulations accurate, complete, and compatible with the utility’s internal tools?
Needless to say, projects that proactively address these concerns are more likely to receive timely approvals. Utilities are also more receptive to developers who speak their technical language and offer solutions, not just applications. By anticipating utility feedback, you can reduce the risk of redesigns, curtailments, or queue delays.
Your goals are likely to secure quick interconnection approval, to hold your capex and opex within pro forma, and to minimize redesigns after queue submission. However, you may find yourself frustrated by:
• Inconsistent or Unclear Utility Feedback: Different utilities request different models, data fields, and even simulation methodologies. What passes in one state may be rejected in another.
• Late-Stage Surprises: Findings in short circuit or dynamic studies can force equipment changes or curtailments months after interconnection documents were submitted.
• Coordination Gaps: When the one line and application are done by one party and the advanced studies by another, the handoffs chew up time and introduce inconsistencies.
Proactive interconnection planning makes these items more predictable. You present solutions instead of problems by modeling your asset, and you are doing it in the file formats the utility analysts understand.
Engineering for Approval
Pure Power treats interconnection as a design goal, not just a study deliverable. The team coordinates with utilities and designs toward their criteria, preferences, and study methodologies from day one.
Utility Specific Know How
Requirements differ: some utilities are PSCAD first; others prefer PSSE or rely heavily on ASPEN for protection reviews (for example, developers interfacing with Eversource frequently see ASPEN requests). Knowing why those nuances exist avoids you spinning your wheels.
A Solutions Playbook
When studies flag issues (e.g., voltage regulation violations on rural feeders), Pure Power works through three solution lanes with the developer and the utility: 1) No /low cost utility adjustments (settings changes), 2) Targeted utility upgrades (paid by the project), or 3) Project side design optimizations (size/controls/equipment). The “right” path depends on technical feasibility and project economics, and the team helps surface concrete options early so finance can choose with eyes open.
One Partner, Fewer Scrambles
Many developers learn months after submission that the utility requires advanced simulations, and they get a one week clock to deliver or risk getting pushed from the queue. Working with a team that can do both the interconnection one line and the advanced simulations avoids last minute vendor hunts.
PSCAD (Electromagnetic Transients / Dynamics)
• What it Shows: Inverter behavior during faults, ride through performance, control interactions, switching, and transient phenomena that steady state tools can’t capture.
• Why Utilities Care: With large inverter-based resources, disturbance performance and system stability are front and center. PSCAD models let utilities test your plant in their own cases and confirm it will behave as expected.
• Developer Takeaway: PSCAD de risks “will it stay online and behave?” questions that can derail approvals late.
PSSE (Steady State Power Flow & Contingency)
• What it Shows: Base case and N 1 scenarios for voltage and thermal limits, reactive power needs, and transfer capability.
• Why Utilities Care: It reveals whether your project overloads lines/transformers or pushes voltage outside limits in day to day and contingency conditions.
• Developer Takeaway: Early PSSE runs identify constraints, enabling re siting, re sizing, or reactive support decisions before filings.
ASPEN (Protection / Short Circuit & Coordination)
• What it Shows: Fault current contributions, device duties, and relay coordination with existing protection schemes.
• Why Utilities Care: Mis coordination leads to mis operations and outages—the thing utilities are most accountable for. ASPEN analyses verify that your plant integrates safely with their protection philosophy.
• Developer Takeaway: Clean protection coordination keeps reviews moving and prevents expensive retrofit demands.
No single tool answers every grid question. PSCAD addresses fast dynamics, PSSE covers steady state and contingencies, and ASPEN validates protection. Together, they provide a holistic picture of grid impact and an approval ready package.
Developers who anticipate utility asks and submit approval oriented designs will move through the queue faster and with fewer surprises. Pure Power is leaning into this shift by combining traditional interconnection design (one lines, applications) with advanced power systems modeling to present solutions rather than generate RFI cycles.
This is how technical rigor turns into business value:
• Reduced Interconnection Risk: Utility ready simulations aligned to local preferences materially improve approval odds.
• Predictable Costs: Instead of open ended “maybe” fixes, you get concrete solution paths (utility settings vs. utility upgrades vs. project side changes) to price and compare.
• Faster Timelines: You avoid trial and error; “Here’s the specific change that addresses the voltage regulation issue” which keeps you moving.
• Credibility with Utilities: Clean models, clear assumptions, and responsive iterations build trust with reviewers.
• Improved Bankability: Fewer redesigns and clearer mitigation plans lower technical risk in diligence.
“We do what we have to do because the end game is a defensible study package—models and reports the utility can run and approve,” says Ben Roeland.
Interconnection is now a competitive differentiator. Developers who are on top of their game prepare: they bring PSCAD, PSSE, and ASPEN to the table early; they design for approval; and they partner with teams who speak the utility’s language.
If you’re evaluating sites or sitting in a congested queue, Pure Power can run an early stage interconnection assessment, scope the right models for your utility, and lay out mitigation options if needed.
For more information out more about de risking your path to approval or our solar + storage engineering services please email info@PurePower.com.