Short answer for 2026: buy proven silicon (TOPCon, HJT or back-contact). Perovskite and tandem results are real and fast-moving, but we found no verified US homeowner product with an established warranty. Waiting for one is not a reason to delay a purchase you need.
Four things people call "available"
Keep these apart: a research cell (a tiny, lab-measured device), a commercial module (a full-size panel made in a factory), a customer shipment (modules delivered to a buyer, often a utility), and a homeowner product (orderable through installers, with a consumer warranty and support). Almost every headline is about the first.
Tracker, dated October 2, 2026
| Item | Kind | Reported figure | Status | Basis |
|---|---|---|---|---|
| LONGi perovskite-silicon tandem | Research cell | 35.5% (July 15, 2026) | Lab only. Not a module. | Manufacturer, reports ESTI certification; certificate not inspected |
| DOE benchmark | Research cells | 26.1% perovskite-only; 33.9% tandem | Historical, as of April 21, 2024 | U.S. DOE |
| Oxford PV | Commercial module | 24.5% | First commercial shipment to a US customer for a utility installation (Sept 2024). Homeowner retail UNVERIFIED | Manufacturer announcement |
| Trinasolar full-size tandem | Module | 907 W, 29.2% (reported) | Reported volume shipments 2028 to 2029; not sold in the US | Secondary report of a manufacturer claim |
| UNSW outdoor trial | Field test | Up to 160 commercial perovskite and tandem modules | Started October 1, 2026 (reported) | pv magazine report |
Perovskite-only panels: broad US homeowner availability, certification and consumer warranty are UNVERIFIED. The Department of Energy lists durability, manufacturing scale and validation as open research challenges.
Why cell records do not equal roof panels
- Area. Records are set on small cells. Full-size modules lose efficiency to larger area and connections: the 35.5% cell versus a 24.5% commercial module is the gap.
- Time. Perovskites are sensitive to moisture, heat and light over time. Reported lab stability tests run for weeks or months, while rooftop warranties run for decades.
- Warranty. We found no verified standard 25-year homeowner warranty for tandem or perovskite modules.
- Certification and service. A product also needs safety certification, installers who stock it, and a manufacturer that will still exist in 20 years.
The test that matters more than the next record is outdoor field data, which is what projects like the UNSW trial are designed to produce.
Claims we could not verify
- Reports that Tandem PV would begin sales later in 2026, backed by letters of intent. Letters of intent are not delivered modules, and the reports describe utility-scale customers.
- Reports of a 2026 Oxford PV module at about 26% with a 15-year warranty. We found this in a single trade report only.
- Any claim that a 35% panel is on sale. The 35.5% figure is a research cell.
Quick answers
Can I buy perovskite solar panels for my house?
We could not verify a perovskite or tandem panel orderable through ordinary US residential channels with a consumer warranty. Commercial shipments have gone to utility-scale customers.
Should I wait for tandem panels before going solar?
Not on current evidence. Silicon panels are proven, warranted for 25 years or more, and a purchase delayed also delays the savings. Tandem warranties and homeowner supply are not established.
What is the highest solar efficiency ever?
The highest figure we found is a 35.5% perovskite-silicon tandem research cell reported by LONGi in July 2026. It is not a commercial panel.