The TMB Horta bus depot is one of the most significant logistical infrastructures of Barcelona’s metropolitan transport network, both for its operational capacity and its commitment to sustainability and energy efficiency. Opened in 2003 and located in the Horta district, this facility houses a third of TMB’s bus fleet daily, establishing itself as an international benchmark for its landscape integration and the application of advanced environmental technologies.
With a capacity for around 300 vehicles, the depot functions as a parking and housing centre for the bus fleet, but also integrates a maintenance workshop, service areas (vehicle washing and refuelling), and office spaces from which the logistical operations necessary for the proper functioning of the service are coordinated.
In 2024, in line with its commitment to the energy transition, a photovoltaic plant was installed to cover a significant part of internal energy demand, reinforcing the efficient and sustainable management model that characterises the facility. Accordingly, Transports Metropolitans de Barcelona (TMB) required prior auditing of the photovoltaic project and executive and site management to ensure its proper implementation.
The audit of the executive project for the solar panel installation at the Horta depot verified the adequacy of the technical proposals. In parallel, executive and site management ensured the correct execution of the installation.
The photovoltaic installation is divided into two distinct areas: the roof of the office and workshop building, and the south façade canopy. Together, these areas cover a total surface of 2,120 m².
A total of 820 solar modules of 550 Wp each were installed, providing a combined peak power of 451 kWp. On the roof, 676 modules were placed, while 144 modules were installed on the canopy, fixed directly onto beams. The modules are connected through 4 inverters (three of 125 kWn and one of 33 kWn), located in the inner courtyard and protected by 2000 A automatic switches that coordinate the injection into the low-voltage grid and prevent simultaneity with the generator set.
The photovoltaic installation incorporates a monitoring system compatible with the inverters. Its purpose is to measure consumption and, in compliance with Royal Decree Law 244/2019, ensure that no energy is injected into the grid. Furthermore, to take advantage of surplus energy, the system was designed to allow for the future storage of excess energy in batteries.
The solar plant covers up to 56% of the depot’s daytime consumption and 22% of total energy consumption, with an estimated annual production of 663.6 MWh. This generation level achieves a high degree of self-consumption (over 85%) and represents annual cost savings of more than €155,000. In addition, it prevents the emission of 181 tonnes of CO₂ per year, thereby contributing to the decarbonisation of public transport and consolidating the Horta depot as a model of energy efficiency and smart urban management.
