Onyx Solar has supplied its photovoltaic solar technology to be part of the refurbishment where it has been installed as a skylight solution for the new facility of ACCIONA, called ‘Ombú Building’ and located in the district of Arganzuela, Madrid, Spain.


The building is an innovative office complex for the Spanish infrastructure and energy company ACCIONA. Together with architecture studios Foster + Partners and Ortiz.León Arquitectos, ACCIONA has carried out a comprehensive rehabilitation of this industrial building to turn it into a unique office complex with the highest standards of sustainability, social impact and energy efficiency.




ombu acciona office photovoltaic skylight onyx solar



  • superficieTotal Area - 140 M2
  • electricidad generadaElectricity generated in 35 years  - 256,308 kWh
  • puntos de luzTotal lighting points operating 4 hours per day in 35 years - 504 lighting points
  • emisiones CO2 evitadas CO2 emmisions Avoided in 35 years - 171 Tons of CO2
  • barriles petroleo ahorradosBarrels of oil saved in 35 years - 151 barrels


Example of a feasibility study of amorphous silicon photovoltaic skylight in Madrid:


  • superficie Payback time  < 6.2 years
  • electricidad generada Internal rate of return (IRR)  17.1 %




* Onyx Solar Energy S.L. makes no representations, warranties or guarantees, whether express or implied, that the content in the report is accurate, complete or up to date.


The central skylight brings natural light to the interior, reducing the need for artificial lighting, while the glazing incorporates photovoltaic technologies that generate free and clean electricity.



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The installation has 140 m2 and it is composed of 31 low transparency amorphous silicon glass units with measures 3,376x1,198 mm, 3,376x1,203 mm and 3,376x1,212 mm. Each module has a glass configuration of 6+3+6 mm and a 16 mm argon chamber to provide additional thermal and acoustic insulation.



photovoltaic skylight ombu acciona office 4


The construction, inaugurated in June 2022 by José Manuel Entrecanales (Executive President of ACCIONA) and the mayor of Madrid, integrates 10,000 m2 of newly created urban landscape in addition to 2,400 m2 of green areas. The project unifies a unique mix of private and public land with green landscaping that extends to the adjoining Mendez Alvaro station and South Bus Station. 


In the landscaping intervention and regeneration of the area in which a total of 12,400 m2 of green areas have been created, more than 350 trees and 28,000 plants of different species have been planted.


Originally built in 1905 by the architect Luis de Landecho, the historic building once supplied energy to the surrounding areas. It later fell into disuse until ACCIONA acquired it in 2017, saving it from demolition.



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Ombú project is one of the most sustainable projects by Foster + Partners and it was presented by Chris Trott, Head of Sustainability, at COP26 in Glasgow as a case study for the World Green Building Council. 


RAFAEL-VINOLY“The design reduces embodied carbon by 25 % when compared to a new build over the whole life of the project, while making allowances for future refurbishment. The operational energy is calculated to be 35 % below normal expectations."


Chris Trott, Head of Sustainability of Foster + Partners


The building meets the European Commission's standards for “Near Zero” Energy Buildings and is pre-certified to LEED Platinum standards. It has been retrofitted to qualify for WELL gold-level wellness standards and is registered for Net Zero Energy certification by the International Living Future Institute of the United States.


If you would like to learn more about this project, read here the full press realeses of ACCIONA and Foster + Partners.




Property owner: ACCIONA
Architects: Foster + Partners
Local support architects:  Ortiz.Leon Arquitectos
Engineers: Proyectos e Ingeniería Llerena

Electrical installers: Magic Block Engineers



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