The prosumerism involving self-consuming green energy generated by small power producers significantly contributes to energy transition and sustainable development. Its practical implementation requires creating strong incentives for businesses and households. In Ukraine's example, this study covers a gap in substantiating business solar prosumerism in a transition economy. We used statistical and comparative analyses to assess the necessary legal and organizational conditions for developing the solar power sector and confirmed its positive outcomes. We applied investment analysis to substantiate the economic feasibility of converting industrial green energy producers to prosumers. The net present value, profitability index, and discounted payback period of constructing industrial photovoltaic solar power plants with 100, 300, 500, and 700-kW capacity were evaluated. Three options for the ratio “green electricity self-consumed/sold at a feed-in tariff” were chosen: 1) 20/80; 2) 50/50; 3) 100/0. We found that pure self-consumption was the most profitable and boosted creating the business solar prosumer class. Using multifactor and comparative analyses, we identified the prospective post-war factors of prosumerism, including electricity prices, green energy sales taxation, investment incentives, etc. The policy recommendations of the study contain the business feed-in tariff cancellation, investment support for deploying energy storage systems and prosumer microgrids.