Internet of Things (IoT) makes a significant contribution to development in economical, social and ecological terms. In this work, the current context to successfully apply IoT in developing countries to achieve the Sustainable Development Goals (SDGs) of United Nations is studied. Potential and opportunities of the IoT in the developing world as well as the current challenges of IoT in developing countries are reviewed. The research methodology is focused on the IoT context in the developing world as well as profitable IoT projects carried out in developing countries, using the SDGs as a reference. Key features as a technical challenges, environmental conditions or social differences are studied to contextualize IoT in developing countries. Finally, the combination of low-cost IoT and pay-as-you-go is presented as the best scenario to better disseminate the Internet of Things for Development (IoT4D) to achieve the Sustainable Development Goals by 2030.

A novel datalogger based on free software and hardware has been designed, built, programmed and installed as an experimental prototype in multiple sites. Remote monitoring extends the effectiveness of the datalogger in areas deprived of electrical grid and traditional wired telecommunication networks. The integration of Internet of Things (IoT) in solar measurement systems allows the remote monitoring of small stand-alone photovoltaic (PV) systems, enhancing the performance and the maintenance of the system. The datalogger measured electric and climatic parameters (up to 14 parameters, expandable) with the required accuracy established by the IEC61724 standard; to include 3G technology in it allowed the stand-alone PV systems system monitoring remotely via web or via mobile application, all at low cost. An outdoor campaign of over 12 months under the harsh environmental conditions at multiple locations was performed to test the new datalogger under real and different conditions demonstrating the robustness and the reliability of the system.

COVID-19 has not affected all countries equally: developing countries have been more disadvantaged by the pandemic. Regarding global development, the COVID-19 pandemic has forced a step back in the path to attaining the Sustainable Development Goals (SDGs). The SDGs most negatively affected by the pandemic are identified here: education, health, and work. Then using the SDGs as a reference, this research explores the new challenges faced by developing countries and the impact of the Internet of Things (IoT) after COVID-19's emergence. IoT solutions carried out in developing countries during the pandemic have been identified and reviewed. Successful Internet of Things for Development (IoT4D) projects, in relation to the SDGs, are highlighted. New social and technical challenges that have emerged for the IoT4D as a consequence of the pandemic are then studied. This work concludes that the future of IoT4D in the wake of COVID-19 should focus on the use of low-cost IoT devices for the SDGs most affected by the pandemic. After an exhaustive study, the Intelligent Internet of Things (IIoT) has been determined to be a key actor in the pandemic's wake, with a leading role in the health sector. The proposed approach includes an extensive study of the new role of the IoT4D for achieving the SDGs in our forever changed world.

Dataloggers installed in rural regions of developing countries need to be autonomous, robust, and have good recording capacity as they may be exposed to harsh environmental conditions. An extremely hot, dry, and dusty climate can imply additional wear and tear toequipment. A test procedurewas designed and run in a confined space to control climate conditions to test the datalogger. An outdoor campaign lasting more than three years was performed at the Instituto Madrileño de Estudios Avanzados (IMDEA) Water Institute, in Alcalá de Henares (Madrid, Spain) and at the Escuela Politécnica Superior (EPS) Linares (Jaén, Spain) to test the low-cost datalogger under real conditions. The results demonstrated that it was robust and endured extreme weather conditions. In order to avoid the loss of data, a new version with a redundant system based on an SD card was implemented and tested under real conditions.

An integrated approach including three main applications of solar energy was followed to design a series of hands-on experiments for schoolchildren (6-10 years-old) with the objectives of promoting solar energy, increasing environmental issues awareness and attracting more students to the field of science. Solar energy outreach activities can be an ideal starting point to foster interest in science and technology from an early age, but adequate initiatives should be carefully design. In this article we present the different solar energy based activities that the University of Jaén (Jaén, Spain) and IMDEA Water Institute (Alcalá de Henares, Spain) have developed in the last years.