![]() It can be seen that there are multiple periods when the 1.8kW peak rated system is able to produce up to 2kW because it is connected to a 5kW inverter. Figure 4.3 illustrates the significant ramp of output power of the 1.8kW system with a 5kW rated inverter on a cloudy day. Furthermore, clouds are largely responsible for rapid changes in the output of PV power generation, because it causes drastic changes in solar insolation, and it can reduce efficiency of 60% in a matter of seconds. The rising and setting of the sun regularly leads to 10-13% change in PV output over a period of 15 minutes for a single-axis tracking PV system. The sun changes position throughout the day from east to west. One is equipment grounding, which is for PV module frames, racks, enclosure, conduits and other metallic components, and the second is system grounding is for an electrical system to ground, or earth potential. All PV systems have two fundamental grounding systems. The inverter converts the DC power to AC power, then, output power flows through a second safety feature known as AC Disconnect that separates the inverter to the grid. It leads to a PV disconnect, also known as Array DC Disconnect, which is safety feature composed of fuses to act as a circuit breaker and it controls the flow of DC current into the inverter. Left side of the figure represents the power generation from the array that consists of four modules connected in series. Figure 4.2 represents the equivalent topology of the PV system that is connected to the utility grid, except there are more modules in the case study. The research also extends to discuss four possible methods to manage these issues that include diversity, forecasting, demand response and energy storage. The information presented will offer in-depth insights to live data to model and evaluate system performance with variability and uncertainty. Due to non-disclosure agreement (NDA) contracts, module information will not be disclosed. ![]() A case study is provided to investigate the operation of a 1.8kW photovoltaic rooftop power generation that feeds to a 5kW inverter on June 2015 in Arizona, where the climate is hot and dry. Variability and uncertainty in PV system performance is highly influenced by the climate, which affects the amount of sunlight exposed to modules and the surrounding temperature. This can affect the reliability and stability of electric power systems. A lot of attention from both researchers and electric utilities are being conducted to study the impact of PV systems to the electric network, because it is incapable of generating constant power flow. It is important to understand the technical challenges associated with photovoltaic electricity generation. In some cases, storage devices are available to improve the avaibability of the power generated by the PV system. Once the power is converted to AC power, with the use of inverter, it can be injected into the grid and/or utilized by loads. The matrix of photovoltaic arrays are the most essential component as it converts the sunlight to DC power. It consists of interconnected elements such as PV modules, inverters, storage batteries and all installation and control components. The building blocks of a grid-connect photovoltaic system is shown in Figure 4.1. In such case, the power supplied is not associated with a particular electricity customer, and the system is designed to only supply bulk amount of power. Power production from photovolatic systems can also be centralized to a power station, known as grid-connected centralized PV power system. Table 4.1 catagorizes the types of application of photovoltaic systems based on its capacity. Such systems may be small or big and can be integrated into the customer’s premise, on public and commercial buildings, or simply in a built environment to support the utility distribution grid. Photovoltaic systems can be installed to provide power to a grid-connected customer or directly to the utility grid, known as grid-connected distributed PV systems. Hence, series of cell are generally grouped together with a bypass diode connect in parallel, so in a case of shading, the string of cell would be disconnected. On a big scale of PV generation, implementing bypass diode on every cell is not practical, because the cost would too high on manufacturing. This can be improved with the use of bypass diode to ensure the current from the active cells with light generated current flow around the shaded cell. Similar to a cell that is affected by shade, few modules connect in series that are exposed to shade will have the same effect of reduced power output. ![]() the weak cell behaves like an active load that start to dissipate tremendous amount of heat that ultimately can lead to permanent damaged cell, interconnection solder, and the glass.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |