## 1 Introduction  
The evolution of teaching has changed from the times when the teacher was a figure of considerable authority, and classes resembled monologues, to today, where education makes the student the protagonist of his or her own learning process, encouraging creativity and participation. Apart from the teacher-student role and academic methodologies, since 2020, the face-to-face nature of the classroom has undergone significant changes. With the arrival of COVID-19 [1], the face-to-face nature of the classroom, especially higher education, has undergone significant changes. Modern higher education combines face-to-face classes with online learning [2]. This change in the method of teaching affects higher education [3; 4; 5], especially in scientific-technological areas, where a large part of the training depends on laboratory practices. Digital transition in education [6], especially in engineering, cannot be immediate, because students are unable to complete their training without practice with real systems. In order to adapt to this new digital scenario, remote laboratories appear as an interesting solution [7; 8]. The main four types of laboratories are explained below and shown in Figure 1:  
* Virtual laboratory with local access (Figure 1a): The environment is virtual and is accessed locally. All experimental work is performed in a computer simulation. The software tool is installed on a computer that meets the requirements to run it. * Virtual laboratory with remote access (Figure 1b, virtual laboratory): The environment is simulated, and the student accesses through the Internet. The student uses an experimentation interface of a simulated system via the Internet. * Real laboratory with local access (Figure 1c): This represents the face-to-face traditional laboratory where the student performs experiments in a physical plant located in the same room. * Real laboratory with remote access (Figure 1d, remote laboratory): There is a real environment which the student accesses through the Internet. The user is able to manipulate the real plant from anywhere, thus providing greater facilities to students. The main advantages of remote laboratories are [9; 10]:  
* Remote laboratories can be accessed 24 h/7 days a week from an Internet connection, without requiring staff supervision. * Due to more efficient sharing of resources, educational institutions can satisfy laboratory demand with less equipment. * Students from universities with fewer resources can make use of high-tech laboratories. * Students with difficulties in adjusting their work timetable with their class timetable have greater ease when conducting laboratory practices. * The user interface is available to be run on several platforms, ranging from desktop and laptop PCs to tablets and smart phones. * Students can also repeat the laboratory practice as many times as they desire without any extra assistance required from staff in order to gain a better understanding and further knowledge. * Remote experiences can be shared between universities, and students have at their disposal a higher number of laboratories. * Remote laboratories allow access to state-of-the-art experiments, avoiding risks of equipment damage and accidents. With such advantages, many universities have decided to implement remote laboratories in their educational methodology to adapt to this coming digital era. Summarizing the above, taking into account the advantages of remote laboratories and how the European Union (EU) aims to adapt education to the new digital era, this paper presents a solution that integrates a European collaborative network of remote laboratories based on renewable energies technology with standardized information and communications technology (ICT) infrastructure. The next section offers a scientific literature review, revising previous related works, comparing the authors' proposal with these earlier findings, and highlighting the main contributions of the proposal.