AE 868
Commercial Solar Electric Systems

Distributed Generation (DG)


We discussed earlier the value of the utility grid and how it serves as the energy reservoir. Most traditional utility grids are built based on the central generation strategy that entails that the power plant is located somewhere with high capacity to supply loads at different locations through transmission and distribution lines.


For more information about the central power generation, please refer to EME 810 (The Power Grid System). This link is also provided in the review section of this lesson.

On the other hand, Distributed Generation (DG) is a system that generates power near the point of consumption, which is also referred to as the end user. Whether it is a diesel generator or PV array, all power will be injected into the grid system. DG can also be fuel cells, wind turbines, and other sources.

DG systems are becoming a more common supplement to the traditional central power generation. DGs have the advantages of lower power losses since the generation is close to the load, so both customers and utility can benefit from it. Customers can benefit from DG when there are power outages if the DG contains backup storage. Utilities can benefit from DG by expanding its capacity without physically adding new central plants. With these advantages also come some challenges since the DG can be installed anywhere on the utility grid. Most utilities noticed the importance of assuring a safe and reliable DG interconnection without having any negative impacts on the utility grid - especially the distribution power system. This lesson will discuss some related codes and standards that are important to interconnect DG sources to the utility grid in the United States.