Electrification of 1723 underdeveloped, frontier, and outermost villages (3T villages) using renewable energy-based microgrid is vital role in improving electricity access and socio-economic activities in the regions. This development strategy in line with the government of Indonesia's program to reduce Green House Gas (GHG) emissions by 29% in 2030 and to achieve Sustainable Development Goals (SDG's) point 7. The challenges of 3T villages electrification are the location of villages that are spread out, varied renewable energy potential and low economic value. To answer those challenges, this study aims to cluster the villages based on renewable energy resource and electricity demand and to assess techno-economic viability of microgrid. The clustering the villages using Clara method and design the microgrid system by optimization model of Homer Pro, and also financial analysis is carried out using several incentive scenarios. The result shows that there are 4 cluster centers: Sari Tani (Gorontalo), Kubang Kondang (Banten), Tuno Jaya (Maluku), and Sungai Pisau (Kalimantan Barat) with microgrid configurations PV capacity 173 - 607 kWp, WTG capacity 12 kW, and BESS capacity 254 - 946 kWh. For 4 cluster villages, the base-case tariff of EPC business model is 3066 - 4115 Rp/kWh, Public Private Patnership (PPP) business model is 3362 - 4525 Rp/kWh, and Resco business model is 4051 - 5478 Rp/kWh. The most effective incentive scenario is the combination of tax allowances, carbon emissions reduction, and interest subsidy minimum 3% or grant 25% capex which can reduce base-case tariffs by 51-59 %. Hence it becomes below 85% regional cost of generation.