What timeline should I expect a solar project to be built?

Understanding the journey from concept to cash flow

If you're a commercial real estate owner exploring solar, one of your first questions is probably: How long will this actually take?

The answer depends on several factors—from your portfolio size to local permitting timelines—but most rooftop leasing and community solar projects follow a predictable path. Here's what to expect at each stage, so you can plan accordingly and keep stakeholders informed.

Phase 1: Portfolio analysis & feasibility (2–4 weeks)

Before any panels get installed, you need clarity on which properties make financial sense.

What happens: Your solar broker conducts investment-grade financial analysis across your portfolio. Using specialized underwriting tools, they evaluate each property's solar potential based on roof condition, utility rates, incentives, local solar productivity, and market dynamics.

What you'll get: Property-specific financial models showing projected returns, lease rates, and which sites are ready to move forward. This phase eliminates guesswork and ensures you're focusing on the highest-value opportunities.

Timeline driver: Portfolio size. A dozen properties can be analyzed in days; hundreds may take a few weeks.

Phase 2: Competitive bidding (2-3 weeks)

Once you've identified viable sites, it's time to secure proposals from solar developers.

What happens: Your solar broker collects necessary information and manages the bid process, reaching out to vetted developers in your market and creating transparent competition. Developers submit detailed proposals covering lease terms, project design, timelines, and financial structures.

What you'll get: A bid package with multiple offers, levelized for easy comparison. Your Lumen Advisor walks you through the trade-offs and helps you select the partner that aligns with your fund strategy and operational requirements.

Timeline driver: Developer availability and proposal complexity. Strong community solar markets often move faster.

Phase 3: Contracting & legal review (4–8 weeks)

With a developer selected, both parties finalize the legal agreements.

What happens: Attorneys review Power Purchase Agreements (PPAs) or lease structures, negotiate terms, and ensure alignment with your asset management team's standards. Your solar broker sits on your side of the table, protecting your interests throughout.

What you'll get: Executed contracts that lock in predictable cash flows and define responsibilities through project completion.

Timeline driver: Legal review cycles and any custom negotiation needs.

Phase 4: Permitting & interconnection (3–9 months)

This is often the longest phase—and the one with the most variability.

What happens: The solar developer handles permitting with local authorities and submits interconnection applications to the electric utility. Behind-the-meter solar projects typically move faster than front-of-the-meter systems, but timelines vary widely by jurisdiction and project details.

What you'll get: Approved permits and utility agreements authorizing the solar system to be constructed and connect to the building or grid.

Timeline driver: Local permitting efficiency and utility interconnection queues. Urban markets with streamlined processes can approve projects in weeks; large-scale projects may take most of a year.

Phase 5: Construction & installation (2–6 months)

Once permits are in hand, installation begins.

What happens: The developer manages all construction activity—site prep, equipment delivery, panel installation, and electrical work. Your involvement is minimal; white-glove service from your solar broker ensures any owner coordination is seamless.

What you'll get: A fully installed, commissioned solar system ready to generate power (and revenue).

Timeline driver: Project size, weather, product availability, and labor availability. Rooftop installations are often faster than ground-mount systems.

Phase 6: Commissioning & revenue start (1–2 months)

The final step: turning the system on and starting cash flow.

What happens: The developer completes final inspections, receives utility approval to operate, and begins generating electricity. For rooftop leasing arrangements, your lease payments begin.

What you'll get: Predictable revenue streams, Scope 2 emissions reduction for ESG reporting, and documentation for GRESB or other sustainability frameworks.

Timeline driver: Final utility sign-off and any punch-list items.

Total timeline: 12–24 months (typical)

From initial portfolio screening to revenue generation, most commercial solar projects take 12 to 24 months. Here's the breakdown:

• Fast-track scenario (12–15 months): Streamlined permitting, strong developer capacity, simple rooftop lease in a mature community solar market
• Standard scenario (18–20 months): Typical urban permitting, moderate utility queue, straightforward Behind-the-Meter solar project
• Extended scenario (20–24+ months): Complex interconnection, slower permitting jurisdiction, or custom deal structure

What speeds things up?

• Strong community solar policies in your state or region
• Working with an experienced solar broker who coordinates across parties and anticipates bottlenecks
• Clear internal decision-making and streamlined legal review
• Mature local permitting processes and responsive utilities

What slows things down?

• Utility interconnection backlogs (common in high-demand markets)
• Complex roof conditions requiring structural upgrades
• Unclear or evolving local solar regulations
• Extended internal approval cycles or stakeholder alignment challenges

Planning for scale

If you're deploying solar across dozens or hundreds of properties, the timeline doesn't multiply linearly. An experienced solar broker can run multiple projects in parallel, leveraging portfolio intelligence and a competitive developer marketplace to scale solar deployment without scaling headaches.

The key is starting with a clear roadmap. Investment-grade analysis upfront ensures you're focused on the right properties, and end-to-end partnership keeps projects moving efficiently—so you can meet decarbonization goals profitably and generate zero CapEx revenue streams on a timeline that works for your organization.

Ready to get started?

Every portfolio is different, and the fastest way to understand your specific timeline is to run the numbers. Lumen Energy's Lux Engine can analyze your properties in days and provide a detailed roadmap from feasibility through commissioning.

Turn underutilized rooftops into predictable revenue streams—on a timeline you can count on.