# A Sustainable Location-Allocation Model for Solar-Powered
## 1 Introduction  
Rice is the primary food source on Java Island, Indonesia. Even though Indonesia has a large amount of agriculture, its rice supply is still import dependent. The government lacks the ability to maintain food security, and investments in agriculture are still small. A shortage of rice supply may lead to a national stability problem [1]. Most of the shortage issues are caused by poor post-harvest rice management, affecting the quality of rice and reducing its durability [2]. Rojolele is a variety of rice from Delanggu Village. It is fragrant, has big grains, is bright white in color, and has a soft texture when cooked. The name Rojolele is derived from its taste and texture, which people found to be the best amongst all varieties of rice in Indonesia. However, this variety of rice is more expensive than the others because the post-harvest product management is complex and the crop is more vulnerable to pest attacks, since its fragrance attracts planthoppers and sparrows. Most farmers consider the pest issue to be the main reason to refuse planting Rojolele in their rice fields. In addition, Rojolele takes 6 months to be fully grown, whereas the regular variety of rice only takes 3 months to grow. Thus, the popularity of Rojolele has been declining since 1968. On November 2020, BATAN (the government organization for nuclear power) entrusted GMO Rojolele rice to the local farming community. This Rojolele rice takes 3.5 monthsto be fully grown and is more durable against pest attacks. The farming community accepted this offer but decided to use organic production without pesticides and artificial fertilizers. They decided to install UVUS technology assembled by the startup Eokarsa for pest control. The UVUS is a solar-powered, adjustable ultraviolet and ultrasonic pest controller. Solar panels are very suitable for use in Indonesia because of the abundant sunlight from morning to evening, so innovations using solar power should be especially encouraged [3]. The ultraviolet light attracts insects, including planthoppers [4]; then, they can be trapped inside special vials. In addition, a certain frequency of ultrasonic sound dispels sparrows [5]. Universities are expected to be able to take over the process of developing technology of this kind and innovating, which should accelerate the innovation and development of such products so that they can enter the market quickly [6]. Every business requires efficient supply-chain design [7]. If there are too many UVUS, then the investment cost will be higher than it should be. On the other hand, the number of UVUS is directly proportional to the coverage area, in which losses caused by pest infestation are prevented. We designed a supply chain model to determine the optimal locations of UVUS on a rice field. The solution of this model provides the number of UVUS needed and their coordinates, to maximize the profits of the system. This research considers three aspects of sustainability: economic, environmental, and social [8]. Sustainability is an interesting topic in both research and business [9]. It describes the goal of satisfying present demands without sacrificing future generations [10]. Mixed-integer linear programming (MILP) was proposed to solve problems in which the variables of sustainability are constrained to be integers, while other variables are allowed to be non-integers. The environmental aspect of sustainability is determined by the reduction in carbon emissions. This research compares the amount of carbon emissions produced by conventionally powered and solar-powered UVUS. The social aspect of UVUS installment represents the perceptions of the farming community: how they perceive and use the technology. Most of these farmers are not used to modern agricultural technology. Thus, their perceptions were analyzed. For the economic aspect, this research presents the net present value (NVP) and break-even point (BEP) to avoid the risk of losses and simplify the investment planning [11]. Table 1 describes the state of the art of this research.