You know the solar adds value.You can't prove how much. Until now.

There is no percentage that answers that, which is exactly the problem. Two identical arrays on the same street can be worth very different amounts: it turns on how the system is owned or financed and on what terms, which net-metering program it is on and how many years of that program remain, the equipment and its age, whether the installer still stands behind the warranty, and what the utility charges today set against what its rates have actually done over the past decade.

So WattWorth does not estimate a percentage. Our proprietary engine runs 22 data points about that specific system at that specific property through a fixed set of rules and returns one dollar figure, with every answer it was built from printed in full, exactly as the seller gave it. That is a number an agent can put in a listing and defend. “Solar adds value” is not.

Only sometimes, and documentation is what decides it. Under Fannie Mae, Freddie Mac and FHA guidelines, leased and PPA systems are excluded from appraised value entirely. Owned systems can be included, but Fannie Mae’s Selling Guide is blunt about what happens without paperwork: “If insufficient documentation is available and the ownership status of the panels is unclear, no value for the panels may be attributed to the property value on the appraisal.” Separately financed panels get no contributory value either, unless the documents show they cannot be repossessed on default.

So the difference between a system that counts and one that counts for nothing is whether somebody wrote down how it is owned, and most sellers have not. That is the gap this report fills. It is a defensible good-faith estimate for the listing and the negotiation, and it does not replace a licensed appraisal.

It doesn't have to. Buyers hear "long-term commitment" and hesitate, which costs offers. WattWorth models the lease or PPA on its own terms and shows the buyer's agent what the payment actually buys: the payment set against what the utility charges, its escalator set against what that utility's rate has actually been doing, and the savings over the remaining term. That comparison turns a perceived liability into a reason to close.

WattWorth's proprietary engine runs 22 data points through a fixed set of rules. System size and the date the system was connected to the grid, ownership structure and financing terms, the utility's own residential rate and what that rate has actually done over the past decade, the net-metering program and its transition timeline, equipment and warranty status, and the installer's current standing are just some of them. A loan balance, set against a documented system value, becomes a negotiating term (who pays it off, and how much of the value is reflected in the price) instead of a liability the seller just eats at closing. A lease or PPA is modeled around assumption value, because buying it out forfeits the financing company's system warranty and production guarantee. The manufacturer's equipment warranty stays, but the coverage most buyers are actually relying on does not. The same inputs always produce the same number.

No. WattWorth is a rules-based valuation engine, not a language model making its best guess. Every report comes from the same calculation, the inputs are shown, and the result is repeatable. That's what makes the number defensible when a buyer's agent or appraiser pushes back.

The valuation still runs. WattWorth's installer database includes companies that have closed or been acquired, such as SunPower and Titan Solar Power, and installer status is a direct input to the number. A bankruptcy filing changes the answer to the warranty question; it doesn't leave it unanswered.

Seconds. The listing agent emails the seller a WattWorth link, the seller completes a short online questionnaire the same way they'd complete any other disclosure, and the report is emailed to the seller and the agent as a PDF plus a link to an online version. No site visit is required.

The report is $179 and includes three parts: the Valuation Report and Summary with the defensible number and the analysis behind it; a Verification and Transition Checklist showing what a buyer, agent, or lender confirms before relying on the number; and Buyer's Next Steps for the new owner's first year with the system. The agent can pay up front as a value-add, or the seller can pay.

California today, through SDG&E, SCE and PG&E. Nevada, Arizona, Illinois, Texas and Florida are coming online within the next 30 days.

Every report is dated and names the programme it was built on, so what it relied on is on the page rather than assumed. The rules are tracked: when California’s AB 942 set out to end net-metering transfer at sale, the engine followed it through the Assembly, through the amendment that stripped the home-sale clause, and through its death in Senate Rules, and the report says plainly where that left things.

What we do not claim is that a report written today will still describe the law in two years. It is a snapshot of one system under the rules in force the day it was generated, and it says so on its face. If something material changes before closing, a re-run is $49, for 30 days from the day the report was issued. After that the report stays live and shareable for the rest of its 180 days, but it cannot be re-run.