Tech4Win · Project

Transparent Solar Windows That Generate Electricity Without Blocking Your View

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Imagine if every glass window in a building could quietly generate electricity while still letting daylight pour through. Tech4Win built a sandwich-style window that uses two invisible layers — one catches ultraviolet light, the other catches infrared — leaving visible light untouched so the window still looks clear. The UV-catching layer also acts as sunscreen for the organic solar layer underneath, extending its life from a few years to over a decade. The result is a window that converts at least 10% of sunlight into power while remaining more than 60% transparent.

By the numbers

≥ 10%

Power conversion efficiency target

≥ 60%

Average visible transparency target

≥ 70

Color rendering index target

≥ 10 years

Device lifetime target (long-term goal ≥ 25 years)

≥ 1 cm²

Demonstrated UV filter device size

≥ 2.5%

UV selective solar cell efficiency demonstrated

56%

Industry partner ratio in consortium

Consortium partners across 5 countries

The business problem

What needed solving

Commercial buildings waste enormous glass surface area that could be generating renewable energy. Existing solar panels are opaque and ugly on facades, while current transparent solar technologies force a painful trade-off between how much power they generate and how much light they block. On top of that, organic solar cells — the most promising route to transparency — degrade quickly under UV exposure, making them unreliable for building applications that need to last decades.

The solution

What was built

The project built and demonstrated a UV filter and UV-selective solar cell at ≥ 1 cm² scale with ≥ 2.5% efficiency, ≥ 60% transparency, and CRI ≥ 70. They also demonstrated a 4-terminal tandem-like device combining UV and IR selective solar cells — the core building block of their transparent solar window concept.

Audience

Who needs this

Architectural glass manufacturers looking to add energy-generating productsBIPV system integrators seeking higher-performing transparent solar modulesCommercial property developers targeting net-zero energy buildingsFacade engineering firms designing high-performance building envelopesOrganic solar cell producers needing UV-stability solutions

Business applications

Who can put this to work

Commercial Real Estate & Property Development

enterprise

Target: Property developers and building owners managing large glass-facade office buildings

If you are a property developer dealing with rising energy costs and tightening building energy codes — Tech4Win developed transparent solar windows achieving 10% power conversion efficiency while maintaining over 60% visible light transparency. This means your glass facades can generate on-site renewable energy without sacrificing aesthetics or natural daylight, helping meet near-zero energy building requirements.

Glass & Facade Manufacturing

mid-size

Target: Architectural glass manufacturers and curtain wall system producers

If you are a glass manufacturer looking to add high-value products to your portfolio — Tech4Win created a tandem solar window combining UV-selective inorganic coatings with IR-selective organic cells, avoiding critical raw materials. The technology uses industrially compatible manufacturing processes with demonstrated cost reduction potential, giving you a competitive product for the growing BIPV market.

Building-Integrated Photovoltaics (BIPV)

any

Target: BIPV system integrators and solar module producers

If you are a BIPV company struggling with the trade-off between transparency and efficiency in solar glass products — Tech4Win's tandem-inspired structure targets over 10% efficiency with over 60% transparency and a color rendering index above 70. The UV-filtering layer extends device lifetime to 10 years or more, solving the durability problem that has held back organic solar adoption in building applications.

Frequently asked

Quick answers

What would transparent solar windows cost compared to standard architectural glass?

The project objective states the technology targets competitive manufacturing costs and avoids critical raw materials to ensure sustainable mass deployment. Specific per-unit pricing is not available in the project data, but the use of industrially compatible processes and common materials is designed to keep costs viable for the commercial building market.

Can this be manufactured at industrial scale?

The consortium includes PV module producers, industrial equipment developers, and BIPV system manufacturers — 5 out of 9 partners are from industry. The objective explicitly mentions industrial compatible technologies with demonstrated potential for cost reduction. However, the demonstrated device size was at laboratory scale (1 cm² or larger), so scaling to full window panels remains a next step.

What is the intellectual property situation — can we license this technology?

Tech4Win was funded as a Research and Innovation Action with 9 consortium partners across 5 countries. IP generated during the project would be governed by the consortium agreement. Interested companies should contact the coordinator at IREC (Fundació Institut de Recerca en Energia de Catalunya) in Spain to discuss licensing or collaboration opportunities.

How does this compare to existing transparent solar products on the market?

The project targets a combination of 10% efficiency, 60% transparency, and 70+ color rendering index simultaneously — a challenging benchmark. Most current transparent solar products sacrifice either efficiency or transparency. The UV-filtering approach to extend organic cell lifetime to 10+ years addresses a key weakness of competing organic solar technologies.

How long before this technology reaches the market?

The project objective includes a roadmap to place a robust solar window on the market in approximately 10 years from the project start (2019). The long-term targets aim for 12% efficiency, 70% transparency, and 25-year lifetime. Based on available project data, this technology is still in the development-to-demonstration phase.

Does this meet building regulations and standards?

The technology targets a color rendering index (CRI) above 70, which is relevant for building codes governing daylight quality in occupied spaces. The project addresses both EU renewable energy targets and building energy performance requirements. Specific building code certifications would need to be pursued during commercialization.

Consortium

Who built it

The Tech4Win consortium brings together 9 partners from 5 European countries (Belgium, Greece, Spain, France, Italy), with a strong industry presence at 56% — 5 industrial partners including 2 SMEs alongside 4 research centers. The coordinator is IREC, a leading energy research institute in Catalonia, Spain. The consortium was deliberately structured to cover the full value chain: organic materials suppliers, industrial equipment developers, PV module producers, and BIPV system manufacturers. This industry-heavy composition signals serious commercialization intent, though the absence of major glass manufacturers or large construction companies suggests the technology still needs to attract downstream adopters for market entry.

FUNDACIO INSTITUT DE RECERCA EN ENERGIA DE CATALUNYACoordinator · ES
ASCAthirdparty · FR
FUNDACION TEKNIKERparticipant · ES
COMMISSARIAT A L ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVESparticipant · FR
INTERUNIVERSITAIR MICRO-ELECTRONICA CENTRUMparticipant · BE
ARMOR SAparticipant · FR
ADVANCED ENERGY TECHNOLOGIES AE EREUNAS & ANAPTYXIS YLIKON & PROIONTONANANEOSIMON PIGON ENERGEIAS & SYNAFON SYMVOULEFTIKON Y PIRESIONparticipant · EL
ONYX SOLAR ENERGY SLparticipant · ES

How to reach the team

IREC (Fundació Institut de Recerca en Energia de Catalunya) in Barcelona, Spain — search for Tech4Win project coordinator contact via their website or LinkedIn

Order a report on this consortium See FUNDACIO INSTITUT DE RECERCA EN ENERGIA DE CATALUNYA profile →

Next steps

Talk to the team behind this work.

Want to explore transparent solar window technology for your buildings or product line? SciTransfer can connect you directly with the Tech4Win research team and help evaluate fit for your specific application.

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