Abstract:
The cost of installing a solar PV system is on the downward trend every year. Currently, it is competitive to the electricity tariffs. However, in some countries including Thailand, the policy on the purchase of electricity from the rooftop solar PV is still unclear. Thus, owners cannot make the decision to invest in the solar PV system installation on their roof. In addition, the cost of battery has declined steadily. Installing a battery in conjunction with the rooftop solar PV system may help reduce the overall cost considering both rooftop solar PV system and the utility electricity purchased. Generally, the benefit and cost analysis to determine sizes of the rooftop solar PV system and a battery is solved by calculus-based optimization or evolutionary-based optimization such as the genetic algorithm. In addition, charge and discharge patterns of the battery are considered as time series, which is complicated and may take a long computation time to solve the problem. Therefore, this thesis proposes a simpler approach. It will consider the charge and discharge patterns of the battery in the form of a bulk of energy that has certain charge and discharge time and is directly added to the load profile. After that, the problem will be solved by systematically setting a set of possible solutions and then selecting the best value under that set instead of solving it by direct optimization method. The benefits and costs are still in the form of time series, and accurately calculated. The proposed method is applied to the load profile of residential houses by considering the electricity tariff as the progressive rate and to the medium-sized business by considering the electricity tariff as the time of use (TOU) rate. The obtained results are reasonable and close to those obtained from earlier researches. But the complexity of the problem is greatly reduced.