In this paper concerns with protecting and holding green - fresh - beautiful environment in exploiting and using renewable energy. When applying to Quang Ninh province - a nature wonder that was ranked in 2012, author focuses on using photovoltaic system to supply electric power for floating projects on the sea, perhaps they are fixed floating building or moving boat. Solar irradiance in this case, falls down photovoltaic system, differs from fixed photovoltaic system on land. Propose some technical solutions suitably to ensure demand, quality electric power and responding environment, aesthetic requirements at once. Build an isolated electric grid model that has structure as PV-MPPT-DC/DC, AC(BESS) and carries out optimal energy solution in photovoltaic system when irradiance intensity is always unstable including loss suddenly. Research results are represented by simulating in Matlab/Simulink.