From RFP to PTO: A Realistic Commercial Solar Project Timeline

“How long will the project take?” is the second question every commercial buyer asks (right after “what’s it cost?”). The honest answer — that anyone selling solar will try not to tell you — is that the construction part is the fastest piece. Most of the timeline is paperwork and waiting on parties that aren’t your contractor.

Here’s how it actually plays out for a typical 500 kW – 2 MW commercial project.

Phase 1: Discovery & engineering — Weeks 1–4

Week 1: Discovery call, site survey, utility-bill analysis. We pull 12 months of interval data, review your roof condition, identify any structural unknowns. By end of week one we have a rough fit/no-fit answer.

Weeks 2–4: Engineering. Structural analysis, energy modeling, interconnection feasibility study, financing scenarios. You receive a fixed-price EPC proposal — not a placeholder. If you choose to move forward, you sign during this window.

This phase is largely dependent on how fast we receive utility data and roof access. If you can move on both within 48 hours, we can deliver a proposal in 2.5 weeks. If those drag, the engineering phase drags.

Phase 2: Permits & interconnection — Weeks 4–12

This is where most of the calendar lives, and it’s almost entirely outside your contractor’s control.

Building permit (city/township): 2–8 weeks. Some NJ municipalities turn permits in 10 days; some take 60. We’ve worked with both.

Utility interconnection application: 4–12 weeks. PSE&G, JCP&L, and Atlantic City Electric all have different review windows for commercial systems. Some require pre-application studies for systems above certain thresholds. Engineering review and witness-test scheduling are the usual bottlenecks.

Incentive program application: 1–4 weeks for SREC/SuSI registration in NJ. Other state programs (NY-Sun, PA-SREC) have their own windows.

These three tracks run in parallel. The slowest determines when construction can start.

Phase 3: Procurement — Weeks 6–14 (parallel with permitting)

Panel and inverter lead times have stabilized post-2023 supply-chain crunch but still run 6–14 weeks for Tier-1 modules. We typically place hardware orders the day after contract execution to avoid this becoming the critical path.

Pro tip: ask any solar contractor when they’re placing your hardware order. If the answer isn’t “the day you sign,” they’re going to be late.

Phase 4: Construction — Weeks 8–14 on site

Once permits clear and hardware arrives, the construction window itself is short by industry standards:

• 500 kW system: 4–6 weeks on site
• 1 MW system: 6–10 weeks on site
• 2 MW system: 10–14 weeks on site

We run multiple trades in sequence: roof prep and racking → conduit and wiring → panel installation → inverter and electrical commissioning → labeling and signage → final inspection.

Construction is the most visible part of the project but rarely the slowest. It’s the part contractors love to talk about because it’s the part they directly control.

Phase 5: Inspection & PTO — Weeks 14–22

After construction completes, three more reviews stand between your system and producing power:

Final municipal inspection: 1–2 weeks. Building department signs off on the install matching the permit.

Utility witness test: 2–6 weeks. The utility schedules an engineer to verify your system meets interconnection standards. They schedule it. We can’t speed it up.

Permission to Operate (PTO): 1–2 weeks. The utility sends a formal PTO letter authorizing the system to export to the grid.

Until PTO arrives, the system can be physically complete and not producing a single kWh. This is the most frustrating phase for first-time commercial buyers — everything looks done, and you’re waiting on a piece of paper.

The all-in numbers

System size	Realistic total timeline	Best-case timeline
500 kW	5–7 months	4 months
1 MW	6–9 months	5 months
2+ MW	8–12 months	7 months

The “best-case” column assumes everything goes right: permits clear quickly, utility interconnection moves fast, hardware ships on schedule, weather cooperates. Build the realistic timeline into your fiscal-year planning, and treat best-case as upside.

What you can do to compress it

A few things accelerate every project:

1. Get utility-bill data into our hands within 48 hours. Engineering starts day one.
2. Have the property owner (if not you) on board before the proposal goes out. Roof-access agreements are a frequent late-game blocker.
3. Don’t change the design after the permit is filed. Every revision restarts the building department clock.

The rest is execution by the contractor.

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Want a realistic timeline for your specific project? Tell us about the building, the system size you’re considering, and the utility serving the address. We’ll come back with a Gantt that breaks out every phase. Get a project timeline →