Self-Consumption Evaluation for Grid-Connected Photovoltaic Systems Considering Ramp Rate Limit

Grid-connected rooftop photovoltaic (PV) systems are a promising solution to reduce electricity bills and support sustainable development in residential areas. Although excess PV power can be sold to the grid at attractive tariffs, premium feed - in tariffs have been discouraged in many countries. Instead, self-consumption policies have been encouraged to promote local generation and consumption. Rooftop PV systems are connected to the grid; thus, local grid codes are applied to maintain a stable and reliable system operation. A high PV power ramp rate (fluctuation) typically imposes several difficulties: voltage fluctuation problems and shorter electric appliance lifetimes. However, previous studies have failed to consider the PV power ramp rate limit when evaluating self-consumption. In addition, neglecting the ramp rate limit leads to a PV system with a lower self-consumption rate in practical implementation due to ramp rate limitations. Therefore, this study focuses on a self-consumption evaluation in grid-connected PV systems considering the ramp rate limit. A modified inverter-based ramp rate control method is considered to maintain PV power fluctuations within ramp rate limits. Several ramp rate limits are assigned to the ramp rate control method in a comparative study, where two scenarios are considered: low and high PV power fluctuations. The comparative results reveal that PV ramp rate limits positively affect the self-consumption rate but negatively affect the self-sufficiency rate.