Roof Condition, Age, and Solar: When to Install, When to Re-Roof First
The single most expensive solar mistake isn't picking the wrong panel — it's installing on a roof that fails three years later. Here's how to time it.
Part of our guide to commercial solar.
The simple rule
A solar system is designed to run for decades. The roof under it needs to last at least that long, or you'll be paying to remove and reinstall panels mid-stream.
What to check by roof type:
- TPO / PVC (commercial and multifamily): the membrane's age and warranty against the system's planned life.
- Asphalt shingle (smaller multifamily): age and condition; shingle roofs often need replacing before a solar system reaches the end of its life.
- Metal standing seam: long-lived; usually suitable if structurally sound.
- Built-up bituminous: variable; site assessment required.
A roofer's inspection and the manufacturer's warranty terms decide it, not a rule of thumb.
When to re-roof first
If your roof will need replacing within the first few years of the system's life, re-roof before solar. The re-roof can sometimes be included in the project funding, and you avoid paying to remove and reinstall the array later.
Many operators (us included) will quote both bundled and unbundled options.
When to install on the existing roof
If a recent inspection confirms the roof has long remaining life, install now. Every year of delay is a year of foregone savings or revenue.
The middle case
The roof has some life left, but not the system's full life. The right call depends on:
- How aggressive your hold horizon is
- Whether the operator offers an R&R reserve
- Whether the financing structure (PPA vs. owned) absorbs the cost
For PPAs, the operator typically carries R&R risk. For owned, you do. Price accordingly.
How NOI handles it
Every site assessment includes a structural and roof condition review. If your roof is too old, we'll tell you. We don't install on doomed roofs because it's bad for everyone — including us.
If a re-roof is needed, we can either bundle it into the project (financed) or refer to a roofing partner for a standalone quote. Then we time the solar install to match.
The cost of getting this wrong
Removing and reinstalling a system mid-life means a quoted removal and reinstallation cost plus lost output while it is down. Worth getting right the first time.
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