Being located along the equator and receiving an abundance of sunlight throughout the year, Solar PV as a renewable energy alternative becomes an enticing prospect for Indonesia. In order to further market penetration of residential rooftop solar PV, it is crucial to understand what the market wants and needs from said product, in order to improve solar products and services. Therefore, the objective of this research is to find out the buying decision process of these adopters in Jakarta. This research uses the qualitative method to examine the consumer behavior of customers during the process of purchasing Rooftop Solar using the Buying Decision process model by Kotler & Keller. The result of this research shows that the buying decision process of residential rooftop solar PV system adopters in Jakarta requires high involvement from the prospective buyers because adopters go through all five stages of the buying decision process before making a purchase. The results provide communication and marketing strategies that companies can use to better provide customers with adequate support and information during the highly involved process of purchase and possibly grow their market.