Every month, buyers close on Bay Area homes with rooftop solar and treat the system like a dishwasher — an appliance that conveys with the house, worth whatever it’s worth. In 2026, that’s a mistake in both directions. An owned system with legacy net metering can be worth $30,000 to $40,000 in avoided electricity costs over the next decade. A 20-year lease with an escalator clause can be a five-figure liability you inherit at closing. Which one you’re buying is knowable before you write the offer — from documents most sellers can produce in a day.
Start with ownership — it determines everything else
Rooftop solar comes in four ownership structures: owned outright, financed with a solar loan, leased, or under a power purchase agreement (PPA). The first question in due diligence is which one you’re looking at, because the answer changes the transaction.
An owned system is an asset that transfers with the house — clean. A financed system usually carries a UCC-1 fixture filing against the property; the seller pays off the loan at close or you negotiate an assumption. Ask escrow to pull UCC filings early — they surface late in the process otherwise, and they can delay closing.
A lease or PPA is different in kind: you’re not buying solar, you’re assuming a payment stream. A typical Bay Area lease from the 2019–2021 vintage runs $160 to $220 per month with a 2.9% annual escalator and often 15 or more years remaining. The net present value of those remaining payments frequently lands between $25,000 and $35,000 — compare that against the buyout schedule in the contract before you decide whether to assume the lease, demand a seller buyout, or reprice your offer.
The interconnection agreement can be worth more than the hardware
Here’s the part most agents miss entirely. California homes with solar interconnected under NEM 2.0 — roughly anything with Permission to Operate (PTO) before April 2023 — are grandfathered on NEM 2.0 export rates for 20 years from their PTO date, and that status transfers with the property. A home with a 2019 PTO keeps NEM 2.0 economics until 2039, no matter who owns it.
The difference is not cosmetic. Under NEM 2.0, exported solar is credited at close to full retail rates. Under today’s NEM 3.0, exports earn the Avoided Cost Calculator rate — averaging $0.04 to $0.08 per kWh, as we covered in NEM 3.0 Realities.
What NEM 2.0 grandfathering is worth
Take a typical 8 kW system producing 11,000–12,000 kWh a year and exporting roughly 40% of it. Under NEM 2.0, those exports generate credits at retail-linked rates — call it $1,500 to $2,000 a year. Under NEM 3.0, the same exports earn $250 to $350. On a home with 13 years of legacy status remaining, that spread alone is worth well over $15,000 — and it’s attached to a single page in the seller’s file: the PTO letter.
One caution: legacy status has conditions. Materially expanding the system — generally more than 10% or 1 kW of added capacity — can forfeit NEM 2.0 treatment. If you’re planning to add panels for an EV or an ADU, model that decision carefully before touching a grandfathered system.
What the system is actually worth in your offer
The 2026 twist: the federal Residential Clean Energy Credit (Section 25D) expired on December 31, 2025. A buyer installing the same system today pays full freight — a representative 8.5 kW array with a 13.5 kWh battery runs about $36,000 with no federal credit behind it. That makes an existing, owned, well-documented system more valuable relative to replacement than it was two years ago.
On the income side, an owned system offsetting PG&E’s average bundled residential rate — about $0.39 per kWh in 2026 — typically saves $3,200 to $4,000 a year for a well-sized solar-plus-battery setup. Appraisers have historically credited owned systems at around $4 per watt (per Lawrence Berkeley National Laboratory research), but appraisals lag the market: bring the production data and the PTO letter to the appraisal rather than hoping the appraiser asks. A leased system, by contrast, adds roughly zero appraised value and can subtract from it.
The document checklist
Before your inspection contingency expires, get these seven items. A seller who can’t produce them is telling you something.
- The PTO letter. The date establishes your NEM vintage — the single most valuable page in the disclosure packet.
- 12–24 months of monitoring data. Actual kWh produced, not the installer’s original estimate. A 20% shortfall usually means shading, soiling, or a failing component.
- Permits and final inspection sign-off. An unpermitted system is a bring-to-code cost, not a selling point.
- Warranty documents and transferability terms. Panels typically carry 25-year warranties; inverters run 10–12. A string inverter replacement is $2,500 to $4,500 installed — if the system is nine years old, price it in.
- Roof age versus system age. A detach-and-reset for a re-roof runs $4,000 to $8,000 on a typical home. Solar on a 20-year-old roof means you’re buying that line item.
- The full lease or PPA contract including the buyout table, if third-party owned.
- Loan payoff letter and UCC-1 release, if financed.
Red flags that reprice the deal — not necessarily kill it
Almost nothing on this list should scare you away from a house you otherwise want. Each is a number, and numbers negotiate. A solar-only system interconnected under NEM 3.0 is exporting power for pennies — budget $12,000 to $16,000 for a battery retrofit to fix the economics (see our guide to whole-home battery backup for how to size it). An aging inverter, a roof nearing replacement, a lease escalator outrunning PG&E’s 6–8% historical rate inflation — all of these convert to credits in escrow if you catch them during diligence rather than after closing.
The PTO letter is the single most valuable page in the seller’s disclosure packet. It tells you whether you’re buying 2019 economics or 2026 economics — and the difference is worth five figures.
An installed solar system is neither a free upgrade nor a trap. It’s a small income-producing asset bolted to the house — and like any income property, it deserves twenty minutes with the actual documents before you commit. If you’re evaluating a home with solar and want a second set of eyes, we’ll model the actual economics of the system you’d be inheriting — talk to our team.
This article is general information, not tax, legal, or investment advice. Lease terms, NEM status, and incentive eligibility are fact-specific — verify the details of any system with the utility and your advisors before relying on them.