{"id":2718,"date":"2026-04-13T18:18:24","date_gmt":"2026-04-13T16:18:24","guid":{"rendered":"https:\/\/orbisterrarum.es\/?p=2718"},"modified":"2026-10-26T18:03:39","modified_gmt":"2026-10-26T17:03:39","slug":"especificaciones-tecnicas-para-estudios-geofisicos-en-plantas-fotovoltaicas-2","status":"publish","type":"post","link":"https:\/\/orbisterrarum.es\/en\/especificaciones-tecnicas-para-estudios-geofisicos-en-plantas-fotovoltaicas-2\/","title":{"rendered":"Technical Specifications for Geophysical Studies in Photovoltaic Plants"},"content":{"rendered":"<p class=\"wp-block-paragraph\">Geophysics in Solar Plants<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Photovoltaic plants are facilities that normally occupy large land areas.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">As a result, geological and geotechnical conditions may vary within the same plant. For this reason, it is necessary to properly design the geophysical campaign to reduce geological uncertainties.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This document aims to detail the applications of electrical methods and other geophysical methodologies in order to standardize the number of tests to be carried out within a reconnaissance campaign. Without these methodologies, the number of direct investigations would be higher, resulting in additional cost.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This article provides recommendations based on the extensive experience of the Applied Geophysics Department at Orbis Terrarum in geophysical studies for photovoltaic plants on five continents.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2025\/08\/Especificaciones-Tecnicas-ME-para-nuevas-PFVs-2.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Continue reading or download here<\/a><\/div>\n<\/div>\n\n\n\n<h4 class=\"wp-block-heading\">TECHNICAL SPECIFICATIONS FOR ELECTRICAL METHODS IN GEOPHYSICAL SURVEY REQUESTS FOR NEW PHOTOVOLTAIC POWER PLANTS<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Joaqu\u00cdn Dorronsoro&nbsp;&amp; Christian Merino&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Applied Geophysics Department. Orbis Terrarum Projects.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>RESUME<\/strong><strong><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Photovoltaic plants are facilities that typically cover large areas of land. This often leads to varying geological and geotechnical conditions within the same site. Consequently, a properly designed geophysical campaign is essential to reduce geological uncertainty.\n\nFor this reason, this document details the applications of electrical methods and other geophysical techniques, aiming to standardize the number of tests required in a field investigation campaign. Without these methodologies, the number of direct intrusive investigations would need to be higher, leading to increased campaign costs.\n\nThis article provides recommendations based on the extensive experience of Orbis Terrarum\u2019s Applied Geophysics Department in conducting geophysical surveys for solar PV projects across all five continents.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Key Words:<\/strong> Solar PV plants, renewable energy, geophysics, electrical methods, electrical resistivity tomography (ERT), soil corrosivity.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">RESUME <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Photovoltaic plants are facilities that typically occupy a large area of land. This can result in geological and geotechnical conditions changing within the same plant. For this reason, a proper design of the geophysical campaign is essential to reduce geological uncertainties. Thus, the aim is to detail the applications of electrical methods and other geophysical methodologies in order to standardise the number of investigations to be carried out within a geophysical campaign. In this sense, without the use of these methodologies, the number of direct investigations would be higher and, consequently, an additional cost overrun would be incurred during the campaign. This article provides recommendations based on the extensive experience of the Applied Geophysics Department of Orbis Terrarum in geophysical studies for photovoltaic plants across all continents.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">1. INTRODUCTION<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">This document has been prepared to recommend and standardize the proper methodology for designing a geophysical investigation campaign for new photovoltaic plants. These recommendations are based on: (1) the experience of the Applied Geophysics Department of Orbis Terrarum (<a href=\"http:\/\/www.orbisgeofisica.com\/\">www.orbisgeofisica.com<\/a>), (2) in the technical specifications published by <a href=\"#_bookmark7\">Puell y L\u00f3pez<\/a> (<a href=\"#_bookmark7\">2021<\/a>) for the request of a geological-geotechnical study in photovoltaic power plants (<a href=\"https:\/\/orbisterrarum.es\/en\/orbis\/nuevas-especificaciones-tecnicas-estudios-geotecnicos-plantas-solares-fotovoltaicas\/\">www.orbisterrarum.es<\/a>), and (3) a track record of research across more than 500 solar plants worldwide and over 50 GW constructed.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cost and schedule optimization is a key factor in the proposed investigation campaigns. A comprehensive geophysical study is always required alongside a solar PV project to provide reliable design data, thereby mitigating long-term risks and operational issues over the plant's lifespan. <a href=\"#_bookmark7\">Puell y L\u00f3pez<\/a> (<a href=\"#_bookmark7\">2021<\/a>).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The applications of electrical methods for a geophysical survey complementary to the geotechnical investigation should focus on the following aspects:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Caracterizar el sustrato a partir de modelos geoel\u00e9ctricos.<\/li>\n\n\n\n<li>Analyze the soil corrosion potential for steel.<\/li>\n\n\n\n<li>Providing electrical resistivity data for the design of the grounding network.<\/li>\n\n\n\n<li>Locate the position of the water table, if present.<\/li>\n\n\n\n<li>Detect anthropic fills, cavities, and potential soil contamination.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">In some cases, these studies must be supplemented with additional geophysical investigations to characterize other physical properties, or specific surveys for transmission lines, electrical substations, or access roads leading to the plant. All of these are generally subject to local regulations.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">2. ELECTRICAL CHARACTERIZATION OF THE GROUND<\/h4>\n\n\n\n<h4 class=\"wp-block-heading\">2.1. ELECTRICAL RESISTIVITY TOMOGRAPHY<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Highlighted as the most common and comprehensive investigation, a 21- or 42-electrode Wenner or Schlumberger array with equidistant spacing along a line is used to determine the electrical resistivity of the ground in two dimensions. The interpretation of these results allows for the representation of different geological units in a two-dimensional cross-section, as well as the identification of water tables, the delineation of contaminants, cavities, and<em>\/<\/em>or anthropic fills, and the classification of the penalizing parameter. <em>Z<\/em><sub>2<\/sub> to determine soil corrosivity (DIN 50 929-3).<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"412\" height=\"309\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-12.png\" alt=\"\" class=\"wp-image-2720\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-12.png 412w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-12-300x225.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-12-16x12.png 16w\" sizes=\"(max-width: 412px) 100vw, 412px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Field layout&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"412\" height=\"309\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-13.png\" alt=\"\" class=\"wp-image-2721\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-13.png 412w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-13-300x225.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-13-16x12.png 16w\" sizes=\"(max-width: 412px) 100vw, 412px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">&nbsp; (b) Field layout<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"977\" height=\"246\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-14.png\" alt=\"\" class=\"wp-image-2722\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-14.png 977w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-14-300x76.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-14-768x193.png 768w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-14-18x5.png 18w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-14-650x164.png 650w\" sizes=\"(max-width: 977px) 100vw, 977px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">(c) Processed electrical resistivity profile<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Figure<\/strong><strong>1:<\/strong><em>Characterization <\/em><em>Geoelectric <\/em><em>By means of <\/em><em>la <\/em><em>ej<\/em><em>e<\/em><em>cuci\u00f3<\/em><em>n <\/em><em>of<\/em> <em>Tomographies <\/em><em>electrical.<\/em><em><br><\/em><\/p>\n\n\n\n<h4 class=\"wp-block-heading\">2.2. VERTICAL ELECTRICAL SOUNDINGS (VES)<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Another option for electrical characterization is through Vertical Electrical Soundings (VES) using four-electrode arrays with expanding spacings. This method allows for determining the electrical resistivity at a single point across various depths. Wenner (ASTM G57-20) or Schlumberger configurations are commonly employed due to their rapid deployment. For data processing, inversions of the field-measured (apparent) resistivity values are performed and subsequently transformed into one-dimensional curves yielding true resistivity parameters.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This technique has been superseded by electrical resistivity tomography (ERT), as the latter offers the advantage of providing geological interpretation over a larger area.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"442\" height=\"331\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-15.png\" alt=\"\" class=\"wp-image-2723\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-15.png 442w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-15-300x225.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-15-16x12.png 16w\" sizes=\"(max-width: 442px) 100vw, 442px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">(a) Field layout&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"455\" height=\"321\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-16.png\" alt=\"\" class=\"wp-image-2724\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-16.png 455w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-16-300x212.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-16-18x12.png 18w\" sizes=\"(max-width: 455px) 100vw, 455px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">&nbsp; (b) <em>\u03c1a <\/em>and <em>\u03c1v <\/em> vs. depth<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Figure 2: <\/strong><em>Ca<\/em><em>r<\/em><em>haracterizatio<\/em><em>n<\/em><em> <\/em><em>Geoelectric characterization of the ground by means of <\/em><em>ej<\/em><em>e<\/em><em>cuc<\/em><em>i\u00f3<\/em><em>n<\/em><em> <\/em><em>de SEV\u2019s.<\/em><\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><a><\/a>2.3.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SOIL-BOX<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Electrical resistivity measurement can also be performed in the laboratory using the two-electrode method known as the soil-box. Measurements are carried out on compacted samples saturated with distilled water. Results are presented as curves showing the measured resistivity at various moisture content percentages. This method is recommended for classifying corrosion potential in accordance with American standards (ASTM G187-18) and is also applied for plants requiring the supplementation of DIN 50929 (2018) standards in subsequent phases (pull-out tests, trench backfilling, etc.).<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"812\" height=\"269\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-17.png\" alt=\"\" class=\"wp-image-2725\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-17.png 812w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-17-300x99.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-17-768x254.png 768w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-17-18x6.png 18w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-17-650x215.png 650w\" sizes=\"(max-width: 812px) 100vw, 812px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;                       (b)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Figure 3: <\/strong><em>Ca<\/em><em>haracterization<\/em><em> Geoelectric<\/em><em> of a sample through the execution<\/em><em> <\/em><em>of the soil-box test.<\/em><em><br><\/em><\/p>\n\n\n\n<h4 class=\"wp-block-heading\">3. DESIGN GUIDE<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">The equation <a href=\"#_bookmark0\">(1)<\/a> determines the minimum requirements for electrical resistivity investigations to be carried out based on Orbis Terrarum's experience. This family of curves is defined as a function of the study area and the average terrain slope, as illustrated in the figure. <a href=\"#_bookmark1\">4.<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This relationship has been inferred from the analysis of over 500 plants investigated by Orbis. The influence of topography on the acquired model is highlighted, and the susceptibility that the latter introduces to a geophysical campaign can be noted, as its direct proportionality to terrain variations (erosion, preferential flow paths, vegetation distribution, changes...) is demonstrated. <a id=\"_bookmark0\"><\/a>laterales y verticales de facies,&#8230;).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><img loading=\"lazy\" decoding=\"async\" width=\"42\" height=\"2\" src=\"\"><em>N <\/em>= \u221a<em>S <\/em>\u00b7 <em>P<\/em><em><sub>m<\/sub><\/em><em>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/em>;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <em>N <\/em>(<em>S, P<\/em><em><sub>m<\/sub><\/em>) : \u00ee<em>N <\/em>(<em>S, P<\/em><em><sub>m<\/sub><\/em>) \u2208 N \u2227 (<em>S, P<\/em><em><sub>m<\/sub><\/em>) \u2208 R<sup>+<\/sup>| (<em>S <\/em>\u00b7 <em>P<\/em><em><sub>m<\/sub><\/em>) <em>&gt; <\/em>0,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (1)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Siendo:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>N<\/em><em> <\/em>= Number of tests.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>S <\/em>= Surface area (ha).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>P<\/em><em><sub>m<\/sub><\/em><em> <\/em>= Average slope.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"980\" height=\"666\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-18.png\" alt=\"\" class=\"wp-image-2726\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-18.png 980w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-18-300x204.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-18-768x522.png 768w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-18-18x12.png 18w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-18-650x442.png 650w\" sizes=\"(max-width: 980px) 100vw, 980px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><a id=\"_bookmark1\"><\/a><strong>Figure 4: <\/strong><em>Number<\/em><em> <\/em><em>of tests in \/ of surveys in <\/em><em>funci\u00f3n<\/em><em> <\/em><em>of the surface area to be investigated and its average slope.<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">As Shown in the table <a href=\"#_bookmark2\">1<\/a> the number of tests to be performed (N) is shown for average slopes of 2%, 3%, 5%, 10%, 15%, and 20%, demonstrating, for instance, how a 2% slope is considered homogeneous, whereas a 20% slope yields a higher number of investigations as a result of terrain irregularity.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a id=\"_bookmark2\"><\/a><strong>Tabla 1: <\/strong><em>Number<\/em><em> <\/em><em>of recommended investigations is<\/em><em>g\u00fan <\/em><em>the <\/em><em>size<\/em><em> <\/em><em>and the plant slope.<\/em><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Surface area (ha)               Slope (%)<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 15&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 20 &nbsp;<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u2264&nbsp;&nbsp;&nbsp;&nbsp; \u2264&nbsp;&nbsp;&nbsp;&nbsp; \u2264&nbsp;&nbsp;&nbsp;&nbsp; \u2264&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \u2264&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \u2264<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>2<\/td><td>2<\/td><td><strong>2<\/strong><\/td><td>3<\/td><td>4<\/td><td>5<\/td><td>6<\/td><\/tr><tr><td>5<\/td><td>3<\/td><td><strong>4<\/strong><\/td><td>5<\/td><td>7<\/td><td>9<\/td><td>10<\/td><\/tr><tr><td>10<\/td><td>4<\/td><td><strong>5<\/strong><\/td><td>7<\/td><td>10<\/td><td>12<\/td><td>14<\/td><\/tr><tr><td>30<\/td><td>8<\/td><td><strong>9<\/strong><\/td><td>12<\/td><td>17<\/td><td>21<\/td><td>24<\/td><\/tr><tr><td>50<\/td><td>10<\/td><td><strong>12<\/strong><\/td><td>16<\/td><td>22<\/td><td>27<\/td><td>32<\/td><\/tr><tr><td>100<\/td><td>14<\/td><td><strong>17<\/strong><\/td><td>22<\/td><td>32<\/td><td>39<\/td><td>45<\/td><\/tr><tr><td>300<\/td><td>24<\/td><td><strong>30<\/strong><\/td><td>39<\/td><td>55<\/td><td>67<\/td><td>77<\/td><\/tr><tr><td>400<\/td><td>28<\/td><td><strong>35<\/strong><\/td><td>45<\/td><td>63<\/td><td>77<\/td><td>89<\/td><\/tr><tr><td>500<\/td><td>32<\/td><td><strong>39<\/strong><\/td><td>50<\/td><td>71<\/td><td>87<\/td><td>100<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">As a guideline, when estimating investigations for a site where slopes have not been evaluated, adopting a value of 3% is recommended, although, depending on site heterogeneity (local geology, contamination, groundwater table presence, cavities, and<em>\/<\/em>anthropogenic fills, access roads, facilities...), the number of investigations must be increased to the next level in Table 1, in this case 5%.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">All investigations must be continuously supervised by a specialized technician (Geophysicist<em>\/ <\/em>Geologist, or similar professional with relevant experience) knowledgeable about the client's requirements and project details.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><a><\/a>4. REPORTS<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">The purpose of the results report focuses on the processing and interpretation of the selected electrical method with the aim of establishing soil resistivity values. This makes it possible, on the one hand, to confirm the site geological model and, on the other hand, to evaluate soil resistivity values for the proper design of the grounding system. Furthermore, the soil corrosivity potential is identified to determine its aggressiveness toward buried metallic materials.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The minimum data to be delivered to the client are as follows:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Geophysical investigation location plan \/ Geophysical survey layout plan<\/li>\n\n\n\n<li>Processed geoelectrical profiles (electrical resistivity tomography - ERT) or alternatively 1D true resistivity curves (vertical electrical soundings - VES).<\/li>\n\n\n\n<li>Factor distribution \/ Distribution of the factor <em>Z<\/em><sub>2<\/sub> based on soil resistivity according to DIN 50929-3 (2018).<\/li>\n\n\n\n<li>Cat\u00e1logo de la resistividad calculada en funci\u00f3n de la profundidad y apertura de los electrodos para el correcto dise\u00f1o de la red puesta a tierra (m\u00ednimo 6,50 m de investigaci\u00f3n).<\/li>\n\n\n\n<li>Resistivity distribution maps across the area where the new solar PV plant and electrical substation will be constructed, at four different depths: 0.5 m, 1.0 m, 1.5 m, and 2.0 m (see Figure 5).<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This product can also be built by implementing frequency-domain electromagnetic techniques, with the advantage that the latter are characterized by their rapid execution and ease in detecting lateral resistivity variations and delimiting anthropogenic fills and\/or contaminants.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Depending on the location of the future solar PV plant and client specifications, other geophysical methodologies must be implemented to determine the various parameters explained in section <a href=\"#_bookmark4\">5.<\/a><\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"783\" height=\"739\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-1.jpeg\" alt=\"\" class=\"wp-image-2719\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-1.jpeg 783w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-1-300x283.jpeg 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-1-768x725.jpeg 768w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-1-13x12.jpeg 13w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-1-650x613.jpeg 650w\" sizes=\"(max-width: 783px) 100vw, 783px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><a id=\"_bookmark3\"><\/a><strong>Figura 5: <\/strong><em>Distribuc<\/em>i<em>\u00f3n<\/em><em> of the soil electrical resistivity at a specified depth.<\/em><\/p>\n\n\n\n<h4 class=\"wp-block-heading\">TIME FRAMES<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">The typical timeframes for this type of study\u2014although variable depending on the geophysical methods applied and the size of the area under investigation\u2014are commonly one week for field surveys and an additional week for data processing and drafting the final report for a plant of approximately 100 MW.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><a id=\"_bookmark4\"><\/a>5. OTHER GEOPHYSICAL TECHNIQUES TO BE EMPLOYED<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Depending on the geographic location of the new solar PV plant and based on local regulations, client specifications, project complexity, and seismic hazard, the following geophysical techniques should be considered:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Seismic refraction for modeling the ground based on P-wave velocity (<em>V<sub>P<\/sub> <\/em>) and thereby characterize the rippability or the mechanical properties of the rock mass. This technique stands out for its rapid execution and depth of investigation to estimate geological models that allow for the delimitation of excavatable, rippable, and blastable zones (Figure 6). <\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"983\" height=\"385\" src=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-19.png\" alt=\"\" class=\"wp-image-2727\" srcset=\"https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-19.png 983w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-19-300x117.png 300w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-19-768x301.png 768w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-19-18x7.png 18w, https:\/\/orbisterrarum.es\/wp-content\/uploads\/2026\/04\/image-19-650x255.png 650w\" sizes=\"(max-width: 983px) 100vw, 983px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><a id=\"_bookmark5\"><\/a><strong>Figure 6: <\/strong><em>Distribution profile<\/em><em> <\/em><em>of <\/em><em>\u00e1reas<\/em><em> <\/em><em>excavables, ripables y volables de un perfil de s\u00edsmica de <\/em><em>r<\/em><em>ef<\/em><em>r<\/em><em>a<\/em><em>c<\/em><em>ci\u00f3<\/em><em>n<\/em><em>.<\/em><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Multichannel analysis of surface waves (MASW) or refraction microtremor (ReMi) for the calculation of S-wave velocity (<em>V<sub>S<\/sub><\/em>), caracterizaci\u00f3n de la <em>V<sub>S<\/sub><\/em><sub>30<\/sub> and their subsequent classification based on international standards for the area under investigation (seismic design codes, Eurocode, IBC, ...). Furthermore, surface wave techniques and their subsequent spectral analysis stand out as effective tools for determining soil-rock contacts at varying depth ranges.<\/li>\n\n\n\n<li>Calculation of dynamic elastic deformation moduli for very low strain ranges (<em>E<\/em><sub>0<\/sub>, <em>G<\/em><sub>0<\/sub>, <em>K<\/em><sub>0<\/sub> and <em>\u03bd<\/em>) using combined techniques of <em>V<\/em><em><sub>P<\/sub><\/em><em> <\/em>and <em>V<\/em><em><sub>S<\/sub><\/em><em> <\/em>such as seismic refraction and MASW or ReMi, cross-hole (<a href=\"#_bookmark6\">Dorronsoro y Merino<\/a>, <a href=\"#_bookmark6\">2019<\/a>) y downhole.<\/li>\n\n\n\n<li>Application of the HVSR spectral ratio method or Nakamura technique for the calculation of the site fundamental frequency in active seismogenic zones (site effect).<\/li>\n\n\n\n<li>Vibration recording for response spectrum calculation.<\/li>\n\n\n\n<li>Use of ground penetrating radar (GPR) for underground utility detection.<\/li>\n\n\n\n<li>Implementation of frequency-domain electromagnetic methods as a rapid, reliable, and efficient solution for calculating electrical resistivity in specific cases where electrodes cannot be driven into the ground, in areas where bedrock outcrops, or in those where there is no optimal contact between the pins and the ground (aeolian sands).<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Similarly, this technique proves to be one of the most effective for distinguishing lateral resistivity variations and delimiting anthropogenic fills, karst cavities, and\/or contaminant plumes.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Due consideration must be given to the importance of understanding local regulations and assessing the seismic hazard of the study area where the new solar PV plant is to be constructed, in order to employ multiple geophysical techniques that provide enhanced support to the geotechnical investigation and thereby characterize the ground based on acoustic and resistivity properties, or vibration records.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>For <\/em><em>more information<\/em> <em>Visit<\/em> <a href=\"http:\/\/www.orbisgeofisica.com\/\"><em>www.<\/em><em>orbisgeofisica.com<\/em><\/a><em><br><\/em><\/p>\n\n\n\n<h1 class=\"wp-block-heading\">REFERENCES<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">(ASTM International, 2018). <em>Standard Test Method for Measurement of Soil Resistivity Using the Two-Electrode Soil Box Method (ASTM G187-18)<\/em>. ASTM International: <a href=\"https:\/\/www.astm.org\/\">https:\/\/www.astm.<\/a> <a href=\"https:\/\/www.astm.org\/\">org\/<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">(ASTM International, 2020). <em>Standard Test Method for Measurement of Soil Resistivity Using the Wenner Four-Electrode Method (ASTM G57-20)<\/em>. ASTM International: <a href=\"https:\/\/www.astm.org\/\">https:\/\/www.astm.org\/<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">(Deutsches Institut fur Normung, 2018). <em>Corrosion of metals &#8211; Corrosion likelihood of metallic materials when subject to corrosion from the outside &#8211; Part 3: Buried and underwater pipelines and structural components (DIN 50929-3)<\/em>. Deutsches Institut fur Normung E.V. (DIN): <a href=\"https:\/\/www.din.de\/en\">https:<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.din.de\/en\">\/\/www.din.de\/en<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a id=\"_bookmark6\"><\/a>Dorronsoro, J., &amp; Merino, C. (2019). Study on the ground improvement effect of sleeve pipe grouting in a railway embankment based on the analysis of dynamic moduli using the cross-hole seismic method. <em>Orbis Terrarum Projects (<\/em><a href=\"http:\/\/www.orbisgeofisica.com\/\"><em>www. orbisgeofisica.com<\/em><\/a><em>)<\/em>, (1):1\u20139.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a id=\"_bookmark7\"><\/a>Puell, F. y L\u00b4opez, J. A. (2021). Nuevas especificaciones t\u00b4ecnicas para la solicitud de un estudio geol\u00b4ogico-geot\u00b4ecnico en plantas fotovoltaicas. <em>Orbis Terrarum Projects (<\/em><a href=\"https:\/\/orbisterrarum.es\/en\/\"><em>www. orbisterrarum.<\/em><\/a><em> <\/em><a href=\"https:\/\/orbisterrarum.es\/en\/\"><em>es<\/em><\/a><em> <\/em><em>)<\/em>, (1):1\u201311.<\/p>","protected":false},"excerpt":{"rendered":"<p>Geof\u00edsica en Plantas Solares Las plantas fotovoltaicas son instalaciones que normalmente ocupan una gran superficie de terreno. Esto puede dar lugar a [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":2239,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-2718","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-publicaciones"],"_links":{"self":[{"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/posts\/2718","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/comments?post=2718"}],"version-history":[{"count":4,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/posts\/2718\/revisions"}],"predecessor-version":[{"id":2933,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/posts\/2718\/revisions\/2933"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/media\/2239"}],"wp:attachment":[{"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/media?parent=2718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/categories?post=2718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/orbisterrarum.es\/en\/wp-json\/wp\/v2\/tags?post=2718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}