NEDO, Japan’s state energy research agency, has published new design and construction guidelines for PV systems using flexible solar cells, including perovskite, chalcopyrite, and thin crystalline silicon technologies, as suitable sites for conventional solar installations become increasingly scarce across the archipelago.

The new guidelines address structural load design, frameless mounting methods, and flammability considerations for building-mounted systems. NEDO said in a press release this week that they were developed by a working group drawing on existing standards across architecture and electrical engineering. It noted that it compiled them with input from the National Institute of Advanced Industrial Science and Technology, the Structural Performance Evaluation Institute, and the Japan Photovoltaic Energy Association (JPEA).

Japan has among the highest solar capacity per unit of land area of any major economy, and available sites for conventional systems are diminishing. Flexible, lightweight cells are aimed at low‑load rooftops and building walls where conventional panels can’t be used – areas NEDO says remain largely unused because structural design guidance has been limited. Past damage from typhoons, snowfall, and heavy rain has also raised community concerns about solar equipment safety, which the guidelines are intended to help address.

Perovskite solar cells in particular are advancing through joint public-private development under Japan’s Green Innovation Fund, and domestic capital investment toward gigawatt-scale mass production has begun, targeting 2030. NEDO said the guidelines are designed to give project developers and designers a consolidated reference for safe deployment as that commercial pipeline develops.

The guidelines only cover building-mounted systems. Livestock facilities, horticultural structures, and indoor installations are excluded. Evaluations of wind and snow load structural safety, and electrical safety through combustion and destructive testing, have not yet been completed. A revised edition is expected no later than fiscal 2027.

Japan’s Seventh Strategic Energy Plan, approved by the cabinet in February 2025, called for maximum renewable energy deployment while managing land-use and community constraints – the policy context from which the flexible PV push, and these guidelines, directly follow.

Japan set a target of deploying 20 GW of perovskite solar capacity by 2040, establishing the scale of ambition underpinning the country’s flexible PV policy. In September 2025, Japan’s Ministry of the Environment opened subsidy applications for two programs targeting early perovskite deployment. The first supported sites with high self-consumption rates or emergency power functionality, requiring film-type perovskite cells generating at least 5 kW at locations with load capacity of 10 kg/m² or less. The second promoted battery integration alongside perovskite installations.

In October 2025, NEDO launched a six-year research and development program under the Green Innovation Fund to advance mass production technologies for tandem perovskite solar cells, running from fiscal 2025 to 2030, with real-world demonstration tests on rooftop and ground-mounted systems.

In May 2025, PXP Corp. and JGC Japan Corp. began a one-year, 1 kW grid-connected trial of chalcopyrite solar panels on an industrial building in Yokohama. The PXP modules weigh 2 kg/m² with output of 100 to 120 W/m². JGC developed a non-penetrating sheet-based mounting system for industrial roofs; early results indicated 1 worker could install 100 m² per day. PXP has secured JPY 1.5 billion in funding toward a planned 25 MW chalcopyrite module factory and is separately developing perovskite-chalcopyrite tandem cells.