Despite of the technological advancements on renewable energies and integration of those into the grid, there are still around 800 million people who lack access to the electricity. In order to tackle this problem, solar home systems are being deployed especially in rural areas to create units for decentralized energy generation, based on DC microgrid premises. Integration of solar home systems, especially in developing countries, has great positive effects on communities' economic and social conditions.
In line with transition to cleaner energy resources and utilization of these, this thesis has been carried at DC Opportunities RD to facilitate the rural electrification project. Within this project, the thesis focuses on implementation of a general adaptable firmware based on USB Type-C power delivery protocol on several components of modular solar home system.
Firstly, the report analyses the existing solar home systems with their characteristics on power delivery and energy management. The limitations on the existing projects are studied and the main motivation on deploying the firmware is pointed out. The main objective of the thesis is hence is formulated as achieving and implementing the USB Type-C power delivery protocol with data acquisition layer on prototypes of charging station, power banks and charging hub, that is tailored to rural applications. The firmware design topology is followed to take into account the modularity, scalability and applicable to energy management.
The USB Type-C power delivery firmware is developed by studying and adapting two open source packages. Several adaptation layers are developed and the firmware is implemented using micro controllers, from STM32, that are capable of running operating system with no faults, deploying several layers of tasks and state machines. Power delivery library functions are tackled with layers of software architectures and data monitoring and transmission layer is deployed, in order to validate the system as well as the hardware.
Implemented firmware is developed on the prototypes and tests are run with the current editions of the prototype. The energy management layer and formulated test case will be run and tested on March 2020, in the field test in Ethiopia. This field test will provide results and data, thanks to the developed firmware and acquisition system, in order to achieve a step closer to the ultimate goal of the project, which is implementing low voltage DC microgrid in rural areas.

Access to electricity is a key actuator in order to tackle poverty in areas of limited resources. While the population without access to electricity has a decreasing tendency, still almost 1 billion people continue to live without this basic amenity. This thesis has been carried out at the company DC Opportunities as part of the rural electrification project. On this field, the main activity focuses on developing cost-effective DC solutions in the form of a solar home system which consists of a total of 4 devices including low-power LED lights, a solar charging station, a high-power rate power bank and a power hub. The report analyses various existing electrification projects identifying the characteristics of their approaches in order to recognize the shortcomings of market available products and to build a design criterion. Given that the main target application is aimed at rural areas, a modular approach has been the base of the design criterion with the purpose of tailoring the SHS to developing countries with limited resources. The project analyses each step within this modular process together with the power electronics involved in every stage. The main objective of the project is to perform direct charging between the charging station and the power bank, which consists in feeding power directly from the bus voltage of the charging station into the battery cells with only one active converter. This feature is implemented as a result of the introduction of the power delivery protocol released together with the USB type C connector . This offers a wide variety of possibilities which includes negotiable voltage levels ranging from 5 to 20V. The first element taking part in the direct charging is the charging station .This thesis addresses the challenge of designing and building a circuit with dynamic adjustment of voltage and current in a cost-effective and reliable manner. By adding a digital to analogue converter and 2 operational amplifiers, it is possible to add this feature to a wide range of standard voltage converters available in the market. The report analyses this circuit in 3 steps: first with circuit theory, secondly by simulation and eventually by including the results obtained in an empirical test implemented in one of the prototypes. The power delivery protocol is also beneficial for a power-bank application, which is the second element of the direct charging. It is one of the purposes of the thesis to evaluate the performance of direct charging. Eventually, the report presents the main conclusions derived from the analysis of the aforementioned elements and also covers future lines which include improvements to be implemented within the components of the solar home systems.