Central Java Province targets the achievement of the new and renewable energy (EBT) portion in the energy mix by 2030 at 22.55%. In order to achieve this target, the Central Java Provincial Government has consistently developed the use of EBT, one of which is through the construction of rooftop solar power plants (Rooftop PV Plant) in government buildings. In addition to requiring a fairly high initial investment cost, the construction of a Rooftop PV plant connected to the PT. PLN (Persero) requires a fairly complicated process, so proper planning must obtain optimal results. This paper will discuss an example of a Rooftop PV Plant development plan at the Secretariat Office of the Central Java Provincial DPRD, including the use of electrical energy prior to the installation of a Rooftop PV Plant; an analysis of the condition and availability of the location; the design and system of a Rooftop PV Plant; an estimate of the total potential energy that can generate; the investment costs of a Rooftop PV Plant; as well as evaluating the results of using Rooftop PV Plant. The electricity bill at the Central Java Provincial DPRD Secretariat Office prior to installing Rooftop PV Plant is Rp. 91.308.323,- per month. The recommended PV design, built on an area of ​​197 m2, is a rooftop on-grid PV Plant system with 6 PV arrays, each of which PV arrays are installed with as many as 20 solar modules arranged in series. The total number of solar modules installed is 120 solar modules with a total capacity equivalent to 30 kWp. Based on the simulation results using the PVSyst 6.4.3 software, the Rooftop PV Plant system can generate electrical energy of up to 43,420kWh per year or equivalent to 118.9kWh per day with a performance ratio of 79.4%. The potential for saving electricity costs from the simulation results can reach Rp. 4,034,441.- per month. The results of the evaluation of the utilization of the Rooftop PV Plant through the recording of the inverter monitoring system within 1 (one) year after installation shows the amount of electrical energy produced is 40,558 kWh, so that the manager of the Secretariat of the DPRD Central Java Province office can save a budget of Rp. 3,768,514.- per month from the use of the Rooftop PV Plant. This figure is not much different from the simulation results at planning. There is a difference in the cost savings of electricity payments at the Central Java Provincial DPRD Secretariat Office during 2020 of Rp. 4,493,300,- excluding savings due to the use of Rooftop PV Plant due to implementing the work from home (WFH) system during the COVID-19 pandemic, which resulted in a significant reduction in the use of electrical energy.

The National Energy General Plan has set a target of achieving the Renewable Energy mix by 23% by 2030, to achieve this the transition of energy to RE must be done immediately. Solar energy is one of the opportunities of renewable energy that is very abundant in Indonesia. Along with the issuance of the Minister of Energy and Mineral Resources Regulation number 49 of 2018 concerning the Use of Rooftop Solar Power System by Consumers of PT Perusahaan Listrik Negara (Persero) which provides opportunities for the utilization of PV Rooftop for household and commercial sector. In view of this, the Central Java Government plans to install Rooftop Power Plant in the Micro, Small and Medium Enterprises (MSME) Sector to develop the utilization of RE in the productive sector while improving the economic recovery of the Covid-19 pandemic. The use of renewable energy (EBT) is expected to save electricity costs in MSMEs. The results of planning using Helioscope software showed that in the three MSMEs with different PLTS capacities, namely 1 Kwp, 2.04 KWp and 4 KWp can produce annual energy production of 1,191 MWh, 2,433 MWh and 5,352 MWh respectively. After the installation of the PLTS, it was proven that in the first two months after installation energy consumption can decrease to minimum usage.