Owned vs. Leased: The First Question to Ask
Before any technical evaluation, find out whether the solar system is owned outright or under a third-party agreement. This distinction matters more than almost any detail about the panels themselves.
Owned systems are part of the property. They transfer to you at closing, you get the energy they produce, and there's no ongoing contract with a solar company. The value is included in the home price.
Leased systems and power purchase agreements (PPAs) work differently. A third-party company owns the equipment. You pay either a fixed monthly lease or a per-kilowatt-hour rate for the electricity generated. That agreement follows the house and transfers to you at closing, usually subject to both lender and lessor approval.
The U.S. Department of Energy notes that solar lease transfers can affect mortgage qualification and title insurance. Some lenders won't finance homes with certain lease structures. Check with your loan officer early.
If the system is leased, get a full copy of the agreement. You want the remaining term, the annual payment escalator (many leases increase 2-3% per year), the buyout price, and what happens to the contract if you sell the house before the term ends.
What a Standard Home Inspection Covers
Home inspectors evaluate solar systems visually. That means looking at the panels themselves, mounting hardware, conduit runs, disconnect switches, inverter condition, and visible connections at the electrical panel. The inspector is looking for obvious physical damage, improper installation, and safety concerns.
What inspectors don't cover: actual output verification, permit history review, or shading analysis. They also typically won't access panels on steep roof sections where walking isn't safe.
InterNACHI's standards of practice define this visual scope. If you want output verification or a performance analysis, you need a solar-specific evaluation beyond the standard inspection.
Common Issues That Come Up
Over roughly 3,500 inspections, panels appeared in a few hundred of them. The issues that showed up most often:
Panel surface damage: Hail impacts, debris, and thermal cycling cause micro-cracks in cells. These aren't always visible from the ground but can reduce output. Discoloration or visible cracks in the glass surface are flags worth noting.
Mounting hardware corrosion: Roof penetrations and bracket attachments that weren't properly sealed corrode over time and create leak pathways. Water intrusion near racking hardware is a common finding on systems older than eight years.
Inverter condition and age: String inverters typically last 10-15 years. Microinverters last longer. An inverter displaying error codes or showing visible signs of weathering near its expected end-of-life is worth flagging for further evaluation.
Electrical connections: Improper wiring at the main panel, missing disconnects, or DC wiring not in conduit are code violations that need correction before closing.
Roof condition beneath the array: Inspectors can't see what's under the panels. If the roof is aging, factor in future removal costs when panels need to come off for replacement.
Roof Condition and the Hidden Cost Problem
Panels attached to an aging roof create a compounding problem that buyers often don't price in. If the roof needs replacement in five to seven years, you'll pay to remove the panels, replace the roof, and reinstall. Depending on system size and local labor rates, that removal and reinstallation adds $3,000 to $8,000 on top of the roofing work itself.
Ask for the roof installation date and any maintenance records. Your inspector may be able to estimate remaining life from shingle condition. If the roof appears within five to eight years of likely replacement and the system is owned, factor that cost into your negotiating position.
For leased systems, check who bears responsibility for panel removal and reinstallation when the roof needs work. Most lease agreements require the homeowner to cover those costs even though the equipment belongs to the leasing company. That's worth knowing before you assume solar savings are purely upside.
Documents to Request Before Closing
A complete solar documentation package should include these items:
Permit and inspection records: The installation should have been permitted with the local jurisdiction and passed final inspection. Request permit numbers. Unpermitted solar systems can create title issues, affect insurance, and require corrective permits that delay or complicate closing.
Production records: Most systems include monitoring software accessible through a web portal or app. Ask for 12 to 24 months of production data. Compare actual output against the system's rated capacity using the NREL PVWatts Calculator, which estimates expected output based on location and system specs.
Utility interconnection agreement: This is the document that allows the system to connect to the grid and receive net metering credits. Confirm it's current and can transfer with the property.
Warranty documentation: Panel manufacturers typically warrant panels for 25 years at 80% rated output. Inverters usually carry 10-12 year warranties. Confirm remaining coverage and whether it transfers to new owners.
Homeowner's insurance confirmation: Some insurers require notification when solar is added. Make sure the system is listed on the current policy and that coverage transfers cleanly to your policy at closing.
When to Hire a Solar Specialist
For a basic owned system with clean paperwork, a standard home inspection combined with your own document review may be enough. Consider bringing in a solar-specific inspector or installer for a separate evaluation when:
The system is older than 10 years and you're seeing signs of wear. The seller can't produce production records or monitoring data. Your inspector flags anything unusual at the inverter or electrical connections. There's evidence of leaks near roof penetrations in the panel area. The permit history is unclear or the installation appears unpermitted.
The Solar Energy Industries Association maintains resources for finding qualified solar professionals. A two-hour evaluation from a certified solar technician typically runs $150 to $300 and answers questions a standard inspection simply isn't designed to address.
That cost is minor relative to what you're taking on. If you're buying a home with a 20-panel owned system, knowing whether it's actually performing is worth the price of a specialist's opinion.