# On Hybrid Nanogrids Energy Management Systems--An Insight into Embedded Systems
## 2 Nanogrids Technologies and Architecture
### Nanogrids versus Microgrids
Microgrids are generally used for managing multiple buildings or a small town, whereas nanogrids are usually used for one system (a single house/building, a vehicle, an airplane, a sailboat, or a small community) [11]. Nanogrids can operate in islanded or grid-connected mode, which is a characteristic also found in microgrids [60, 61, 62]. Nanogrids are generally less expensive to install and maintain than microgrids because they are smaller and require fewer components. On the other hand, microgrids require larger and more complex infrastructure, which can result in higher initial costs. The main difference between microgrids and nanogrids  
Figure 2: General DC and AC architectures. Reproduced from [57]. is based on some factors like system size, power rating, load size, complexity, hardware configuration, and control strategy. The margin of these factors between nanogrids and other grids is still debated and is presented in [11]. Table 1 summarizes the comparison between a nanogrid and a microgrid. Nanogrids are typically smaller in size and can be designed to match the specific energy demand of an embedded system, which can result in lower capital costs and operating expenses compared to larger microgrids. Nanogrids also have the ability to incorporate energy storage solutions, such as batteries or flywheels, which can help to further improve the reliability and stability of the energy supply. Nanogrids may be more resilient and secure than microgrids, particularly if the system is designed to operate in island mode. This can be important for embedded systems that require a high level of security and resilience. Nanogrid technology is still relatively new and, as such, may have a higher level of risk and uncertainty compared to more established microgrid technology due to the complexity of the technology and the potential for unexpected failures or downtime. While designed for smaller-scale applications, nanogrids present complex challenges due to the integration of diverse energy sources, such as solar panels, wind turbines and energy storage systems, into localized networks. This complexity can lead to unexpected failures or downtime, a notable vulnerability of nanogrids. Unlike microgrids, which often have redundancy and backup generation, nanogrids may lack such resilience. A single component failure in a nanogrid can disrupt the entire energy supply, raising reliability concerns. In addition, nanogrids may be more vulnerable to cyberattacks and security breaches due to their complex and interconnected nature. This could result in increased maintenance and support costs, more robust security and privacy measures, and a high level of operational flexibility and reliability. However, as the technology becomes more mature and widely adopted, these costs may decrease. While making the distinction between a nanogrid and a microgrid, it is important to note that the two are not always mutually exclusive. The modular design of the nanogrid allows several nanogrids to be grouped together to form a microgrid [63].