## 2 Fixed Tilt Angle System vs. Horizontal Single-Axis Tracker
### Differences Between PV Module Mounting Systems Under Study  
The process of designing a \(PV\) power plant begins with a feasibility study based, among other things, on the following points: (i) analysis of the energy resource, (ii) analysis of performance, (iii) analysis of reliability, (iv) analysis of initial cost. These points, which will influence the choice of \(PV\) module mounting system, will be studied below:  
1. Energy production. The availability of moving parts allows horizontal single-axis trackers to align the \(PV\) field with the sun throughout the day. Therefore, these mounting systems improve energy production compared to fixed tilt angle systems [18]. However, this improvement in production depends on the location of the \(PV\) power plant. Several questions arise with regard to the energy production of horizontal single-axis trackers: Do they obtain energy gain at all times of the year? Do they obtain energy gain throughout the day? These questions will be analysed in this experimental and theoretical study. 2. Reliability. Moving parts in a horizontal single-axis tracker complicate the reliability of the system, as they increase the risk of mechanical failure. As fixed tilt angle systems lack moving parts, these systems are very reliable. In contrast, horizontal single-axis trackers are less reliable, as their operating principle is based on the movement of the \(PV\) field. [PERSON] et al. [20] evaluated two \(PV\) power plants equipped with fixed tilt angle systems and one \(PV\) power plant equipped with horizontal single-axis trackers. The study covered several years of operation, concluding that fixed tilt angle systems were more reliable than horizontal single-axis trackers. 3. Durability. Fixed tilt angle systems have no mechanical problems, due to the simplicity of their components. In contrast, horizontal single-axis trackers, with moving parts, require more maintenance and have a shorter lifespan. 4. Simplicity of installation. Moving parts in a horizontal single-axis tracker complicate installation work. Therefore, fixed tilt angle systems are easier to install than horizontal single-axis trackers. 5. Maintenance costs. Moving parts in a horizontal single-axis tracker increase maintenance. Therefore, fixed tilt angle systems have lower maintenance costs than horizontal single-axis trackers. There is no standardised method for determining maintenance costs [36]. However, many authors use the report by the National Renewable Energy Laboratory [37] to calculate them; the criteria followed in this report, to calculate the annual maintenance cost, are as follows: (i) 0.5% of the initial cost for fixed tilt angle  
Figure 3: Schematic of a horizontal single-axis tracker. systems, and (ii) 1% of the initial cost for horizontal single-axis trackers. Other authors consider that the maintenance costs of horizontal single-axis trackers are double those considered for fixed tilt angle systems [37]. If the maintenance required is minimal, as in the case of fixed tilt angle systems, \(PV\) plants installed in remote locations benefit greatly, as the number of regular checks is reduced. * Initial costs. The absence of moving parts also influences initial costs, as it facilitates the installation of the mounting system. Fixed tilt angle systems have lower initial costs than horizontal single-axis trackers. Horizontal single-axis trackers are 50% more expensive than fixed tilt angle systems [38]. This feature is a determining factor in smaller-scale \(PV\) installations or projects with limited budgets. * Vulnerability to extreme environmental factors. According to a report by the United Nations Intergovernmental Panel on Climate Change (_IPCC_), climate change will notably increase wind loads and extreme phenomena [39]. The operational characteristics of the \(PV\) module mounting system make it susceptible to extreme environmental factors (strong winds or heavy snowfall) causing significant damage to \(PV\) power plants [19].