Abstract: Offshore Floating Photo Voltaic (FPV) is an effective way to deal with the contradiction between photovoltaic development and land resources. However, under the action of sea waves, the photovoltaic panels on a FPV structure always oscillate with wave motion, which makes their angles to the sun change constantly and imposes a great impact on power generation. In this paper, a formula is derived for calculating the radiation energy of the panels under regular sea waves, and the concept of time-equal-dip angle is summarized and introduced. Using the Bohai Bay conditions of regular waves at the same latitude, efficiency ratios are calculated for the irradiated energy between the offshore photovoltaic panels with different dip angles and the onshore ones with the best dip angles. From the calculations, we find that for the panels with different dip angles, variations in the radiation energy under sea waves follow basically the same trend－it decreases with the increase in the average dip angle. A recommended standard of the panel motion amplitude is given as a design criterion useful for estimating hydrodynamic responses in the development of FPV structure.

Key words: offshore floating photovoltaic, evaluation methods, theoretical calculation, radiant energy, wave-induced, floating photovoltaic structure