Prototype for an off-grid photovoltaic system with low cost solar tracking

Abstract

Off-grid photovoltaic systems turn solar light into electricity working apart from the electrical grid. These types of systems tend to use a fixed structure with an optimal orientation for the assembly of the photovoltaic modules. Based on this concept, if it is necessary to increase the production of energy, the number of photovoltaic modules should be increased, which has an impact in the cost of the system. The present investigation explores the possibility of increasing the energy production without having to add more photovoltaic modules, through the use of a mobile solar tracking system attached to the off-grid photovoltaic system. In order for this concept to be useful, it is necessary for the tracking system to have a low cost. This article describes the practical implementation of an off-grid photovoltaic system with a low cost solar tracking system. Two design related decisions were taken in order to reduce costs: first, to implement a tracker with an only axis north-south with an optimal tilt (21° for Aguascalientes), which simplifies the mechanical design in respect to a two axis tracking; second, to divide the daily movement of the actuator in 10 steps, instead of performing a continuous movement, which simplifies the electrical control. The prototype has a monitoring system that can measure the increments in terms of solar irradiation capture in respect to a fixed structure system. The measurements of four full operational days are presented as results, as well as the prototype implementation costs table.