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Most residential solar installations in Denver run 8 to 12 weeks from signed contract to flipping the switch. Here is every phase of that timeline, what can slow it down, and what you can do to speed it up.
Plan for 8 to 12 weeks from signed contract to Permission to Operate. The physical installation itself takes only 1 to 3 days. The rest of the timeline is permitting, city inspection, and Xcel Energy's interconnection review process — all of which Apollo Energy manages on your behalf.
Every phase of the process has its own pace, and knowing what drives each one helps you set realistic expectations and spot opportunities to move faster. Here is exactly what happens after you sign your solar contract in Denver.
A technician visits your home to assess roof condition, measure dimensions, check your electrical panel, and note shading from trees or structures. The engineering team then designs your system — panel placement, inverter type, total size — based on your usage and roof layout. If you are adding a battery backup system, that gets factored in here too.
1 to 2 weeksDenver is one of the fastest cities in Colorado for solar permitting. The City and County of Denver uses the SolarAPP+ automated system, which means many residential permits are issued the same day the application is submitted. For standard rooftop systems on single family homes and duplexes, SolarAPP+ reviews automatically and returns approval in real time. Projects outside standard parameters go to manual review. Colorado law caps permit fees at $500.
Same day to 4 weeksThis is the step that surprises most homeowners. The crew mounts the racking, installs the panels, connects the inverter, and wires everything to your electrical panel. If you are getting a Tesla Powerwall 3 or FranklinWH aPower 2, the battery install happens at the same time. Most homeowners stay in their home throughout. Power is off briefly during the electrical connection — typically under two hours.
1 to 3 daysDenver's building department sends an inspector to verify that the installation meets electrical and building codes. They check panel mounting, wiring, grounding, and the electrical connection to your main panel. If a battery was installed, that gets inspected too. Once you pass, you are one step from generating your own power.
1 to 2 weeksAfter city inspection, your installer submits an interconnection application to Xcel Energy through their Distributed Energy Resource (DER) portal. Xcel reviews in stages: initial review (~3 business days), then program review (~2 business days after the $100 application fee for systems under 10 kW), then engineering review (up to 10 business days). Xcel then issues your Permission to Operate (PTO) — the official green light to turn on your system and start earning net metering credits.
3 to 6 weeksNot all Colorado municipalities move at the same speed. Denver's SolarAPP+ adoption makes it one of the fastest in the state. Here is how the permitting phase typically compares across the Front Range.
| City | Permitting System | Typical Permit Timeline |
|---|---|---|
| Denver | SolarAPP+ automated | Same day (standard systems) |
| Aurora | SolarAPP+ automated | 1 to 3 business days |
| Lakewood | Manual review | 1 to 3 weeks |
| Arvada | Manual review | 1 to 3 weeks |
| Fort Collins | SolarAPP+ automated | 1 to 5 business days |
| Colorado Springs | Manual review | 2 to 4 weeks |
A few variables can push your installation beyond the typical 8 to 12 weeks. Most are avoidable if you plan ahead.
Colorado law requires HOAs to allow solar, but many still have an architectural review process that adds 2 to 4 weeks. Submit your HOA application before or right after signing your contract.
Older 100-amp panels often need upgrading to 200 amps before solar can be connected. This requires a separate permit and adds labor time. Your installer flags this at the site survey.
If your roof needs work before panels go up, that happens first. A compromised roof under solar panels is a problem that compounds over time. Apollo's site survey identifies this early.
In rare cases, Xcel determines that infrastructure upgrades are needed at your location before interconnection can be approved. This is uncommon for residential projects but can add several weeks.
HOA approval is the single most common avoidable delay. If you have an HOA, start the approval process the same week you sign your contract. Colorado law is on your side — HOAs cannot unreasonably deny a solar installation — but their review timelines are not in your control once submitted.
You have more control over the pace than most homeowners realize. A few straightforward actions on your end cut weeks off the typical timeline.
Respond quickly when your installer asks for documents — a recent Xcel bill, proof of HOA approval, or roof inspection reports. Each delay in document delivery stalls the next step in the permitting chain. If you have an HOA, initiate that process immediately. Make sure your roof is in solid condition before signing your contract so there are no surprises during the site survey.
Working with a local Denver installer also helps significantly. A company that files permits with the City of Denver on a regular basis knows the SolarAPP+ system, the Xcel DER portal, and the inspection process inside and out. That local expertise eliminates back-and-forth delays that out-of-state or inexperienced installers routinely run into.
Apollo Energy handles every phase of the timeline on your behalf: design, permitting, installation, inspection scheduling, and Xcel interconnection. Our local permit experience in Denver means we rarely run into avoidable delays. Most of our Denver customers go from signed contract to Permission to Operate in 8 to 10 weeks.
Colorado's weather is generally solar-friendly year-round. Panels install in winter without issue, and Denver's 300 days of sunshine mean meaningful production even in shorter winter days. The physical installation itself is weather-dependent — crews will not mount panels in active snow or high winds — but delays from weather are typically measured in days, not weeks.
The bigger seasonal factor is demand. Spring and early summer see the highest volume of new installations across the Front Range, which can create slightly longer queues for city inspections and Xcel interconnection reviews. Starting your project in late summer or fall often results in a faster overall timeline.
If you are planning to enroll in Xcel's Renewable Battery Connect Virtual Power Plant program when it reopens mid-2026, starting your battery installation now puts you in the best position to enroll immediately when the fund opens.
The sooner you begin, the sooner your system is producing power and reducing your Xcel bill. Apollo Energy handles every step from design through Permission to Operate.
Feel free to reach out to us anytime. We're here to help!
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