Abstract
Buildings that use renewable energy sources, such as sunlight with solar collector technology, are in demand to face climate change. The position of the sun is a pivotal reference for determining the optimum of solar collectors. There are two differences in the optimum results in the equatorial region due to the different perceptions in defining the sun’s position. This study highlights the optimum orientation that is not perpendicular because it reflects the actual position that spreads at the equator. This study aims to prove the sun’s position that spreads in the equatorial region and to show the optimum potential with varied accesses. The investigation is conducted through the angular coordinates of altitude and azimuth. The methodology used is simulation calculation and descriptive analysis by comparison. The simulation calculation uses SunEarthTools.com, based on equations from astronomical algorithms by Michalsky. The validation uses the NOAA Solar Position Calculator, based on equations from astronomical algorithms by Meeus. The targets of the study are to make a profile of the performance of the sun’s position and a profile of the opportunity for the sloped surfaces to accept access. The sun-earth relationship and the season period are the factors that cause differences in the angular range of the sun’s position for each latitude zone. The results prove that the equatorial region has a more spacious range of orientation and a relatively balanced high of elevation in the four main cardinal directions than other regions. The highest points occur twice during the equinoxes for the balanced position between the east and west orientations, and the farthest points happen in the summer solstices for the balanced position between the north and south orientations. The spreading position allows two low-inclined surfaces facing opposite orientations to be exposed simultaneously for long periods, especially in the equinoxes. This study contributes a theoretical insight into the optimum at the equator that has potency for optimum with diverse access.

Key words: Angular coordinate, latitude, opposite orientations, simulation calculation, solar declination angle.