Koichi Nakamura

A grid-connected PV-ECS system with load leveling function taking into account solar energy estimation

In this work, a small grid-connected distributed generation system with load leveling function has been developed using PV panel and ECS. The system can produce power by PV panel, store energy from grid line and PV panel when the load demand is low, and finally supply the stored energy to load during the peak demand. To level the daily load properly, it is necessary to know how much power the PV panel will generate tomorrow. Hence a procedure has also been devised to estimate the output power of PV panel by calculating solar radiation. The accuracy of the calculated soar radiation and PV output power has been verified by practically measured data. Everyday we have to declare, how much power will be taken from the grid line tomorrow, for proper functioning of the system. With an aim to set the optimum value of grid power, to level the load properly and to use 100% output power of PV panel, a simulation program has also been developed. Finally the performance of our system has been studied for several days in different weather conditions, using the estimated output of the PV panel and the simulation program.

A viable grid-connected PV-ECS system with load leveling function using a day-ahead weather forecast

A small grid-connected distributed power generating system based on PV panel and ECS has been developed. The system can produce power by PV panel, store energy during lower demand of load and supply the stored energy to load during higher demand. It takes a fixed amount of power from grid line and supplies to load by day and charges the ECS at night to perform the load leveling function. A procedure to estimate the output power of PV panel has also been developed by calculating solar radiation. To find out the weather dependent characteristic of the PV panel, its output in different weather conditions have been measured and compared with the estimated output. Using this weather dependant characteristic and a day-ahead weather forecast, we can estimate the output power of the PV panel in any weather condition. A simulation program has also been developed to set the optimum value of the power taken from grid line.