{"id":1798,"date":"2026-07-27T10:33:08","date_gmt":"2026-07-27T02:33:08","guid":{"rendered":"https:\/\/jutrion.com\/?page_id=1798"},"modified":"2026-08-07T10:53:43","modified_gmt":"2026-08-07T02:53:43","slug":"calculateur-de-tension-de-chaine-photovoltaique","status":"publish","type":"page","link":"https:\/\/jutrion.com\/fr\/tools\/pv-string-voltage-calculator\/","title":{"rendered":"PV String Voltage Calculator"},"content":{"rendered":"\n<!-- ===== JUTRION PV String Voltage Calculator \u2014 paste into a WordPress \"Custom HTML\" block ===== -->\n<div class=\"jt-calc\">\n  <p class=\"eyebrow\">Solar &amp; DC<\/p>\n  <h1>PV String Voltage Calculator (Cold V<sub>oc<\/sub> &amp; Max Modules)<\/h1>\n  <p class=\"tool-lede\">Find the worst-case cold open-circuit voltage of a PV string and the maximum number of modules that stays within the inverter&#8217;s DC voltage limit. Cold mornings \u2014 not hot afternoons \u2014 set the highest string voltage, and exceeding the inverter limit can destroy it. Use the module and inverter datasheet values.<\/p>\n\n  <div class=\"jt-card\"><div class=\"jt-grid\">\n    <div class=\"jt-inputs\">\n      <div class=\"jt-two\">\n        <div class=\"jt-field\"><label for=\"jt-voc\">Module V<sub>oc<\/sub> at STC (V)<\/label><input type=\"number\" id=\"jt-voc\" value=\"49.5\" min=\"1\" step=\"0.1\" inputmode=\"decimal\"><\/div>\n        <div class=\"jt-field\"><label for=\"jt-beta\">\u03b2 V<sub>oc<\/sub> (%\/\u00b0C)<\/label><input type=\"number\" id=\"jt-beta\" value=\"-0.27\" max=\"0\" step=\"0.01\" inputmode=\"decimal\"><\/div>\n      <\/div>\n      <div class=\"jt-two\">\n        <div class=\"jt-field\"><label for=\"jt-tmin\">Site min. temperature (\u00b0C)<\/label><input type=\"number\" id=\"jt-tmin\" value=\"-10\" step=\"1\" inputmode=\"numeric\"><\/div>\n        <div class=\"jt-field\"><label for=\"jt-vmax\">Inverter max DC voltage (V)<\/label><input type=\"number\" id=\"jt-vmax\" value=\"1100\" min=\"1\" step=\"10\" inputmode=\"numeric\"><\/div>\n      <\/div>\n      <div class=\"jt-field\"><label for=\"jt-mods\">Modules per string (to check)<\/label><input type=\"number\" id=\"jt-mods\" value=\"20\" min=\"1\" step=\"1\" inputmode=\"numeric\"><\/div>\n      <div class=\"jt-note\"><span>\u24d8<\/span><span>\u03b2 V<sub>oc<\/sub> is the negative temperature coefficient of open-circuit voltage from the module datasheet (typically \u22120.25 to \u22120.35 %\/\u00b0C for crystalline silicon).<\/span><\/div>\n    <\/div>\n    <div class=\"jt-readout\">\n      <div><div class=\"jt-rl\">Cold V<sub>oc<\/sub> per module<\/div><div class=\"jt-big\"><span id=\"jt-cvoc\">\u2014<\/span> <span>V<\/span><\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">Max modules per string<\/div><div class=\"v\" id=\"jt-max\">\u2014<\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">String cold V<sub>oc<\/sub> (entered)<\/div><div class=\"v\" id=\"jt-str\">\u2014<\/div><\/div>\n      <div class=\"jt-rec\"><div class=\"k\">Against inverter limit<\/div><div style=\"margin-top:6px\"><span class=\"jt-pill na\" id=\"jt-chk\">\u2014<\/span><\/div><\/div>\n      <button type=\"button\" class=\"jt-copy\" id=\"jt-copy\">Copy result<\/button>\n    <\/div>\n  <\/div><\/div>\n\n  <div class=\"jt-content\">\n    <h2>Why cold weather sets the limit<\/h2>\n    <p>A module&#8217;s open-circuit voltage rises as temperature falls. The coldest expected cell temperature \u2014 a clear, freezing dawn before the array warms \u2014 produces the highest V<sub>oc<\/sub>, and that is the voltage the inverter and all DC components must withstand:<\/p>\n    <div class=\"jt-eq\">V<sub>oc<\/sub>(cold) = V<sub>oc,STC<\/sub> \u00d7 [ 1 + (\u03b2 \/ 100) \u00d7 (T<sub>min<\/sub> \u2212 25) ]\nMax modules = floor( V<sub>dc,max<\/sub> \/ V<sub>oc<\/sub>(cold) )<\/div>\n    <p>\u03b2 is negative, and T<sub>min<\/sub> is below the 25 \u00b0C reference, so the correction raises the voltage above the datasheet figure. Sizing a string on the STC voltage instead of the cold voltage is a common and dangerous error \u2014 it can push the array past the inverter&#8217;s maximum on the first cold morning.<\/p>\n\n    <div class=\"jt-note\"><span>\u26a0<\/span><span><b>Use the lowest credible cell temperature.<\/b> Standards base this on the site&#8217;s record low ambient. The string must stay under the inverter maximum at that temperature with the string as designed, including any future extension.<\/span><\/div>\n\n    <h2>Frequently asked questions<\/h2>\n    <div class=\"jt-faq\">\n      <details><summary>Do I use record low or average low temperature?<\/summary><p>The lowest expected cell temperature, normally derived from the site&#8217;s record low ambient. A milder figure understates the peak voltage and risks exceeding the inverter limit.<\/p><\/details>\n      <details><summary>Which voltage does the inverter limit refer to?<\/summary><p>The absolute maximum DC input voltage \u2014 not the MPPT window. The cold-temperature string V<sub>oc<\/sub> must stay below this absolute maximum; the operating voltage should also sit within the MPPT range for good yield.<\/p><\/details>\n      <details><summary>Does the same voltage size other DC parts?<\/summary><p>Yes. The cold string V<sub>oc<\/sub> sets the minimum voltage rating for the DC isolator, fuses, SPD (U<sub>cpv<\/sub>), and cable \u2014 not just the inverter.<\/p><\/details>\n    <\/div>\n\n    <div class=\"jt-cta\">\n      <h2>Build the DC side<\/h2>\n      <p>With the string voltage fixed, size the combiner, isolator, fuses, and SPD to the same cold V<sub>oc<\/sub>.<\/p>\n      <div class=\"jt-cta-btns\">\n        <a class=\"jt-btn\" href=\"https:\/\/jutrion.com\/pv-combiner-box\/\">Explore PV combiner boxes<\/a>\n        <a class=\"jt-btn ghost\" href=\"https:\/\/jutrion.com\/contact\/\">Get a free quote<\/a>\n      <\/div>\n      <p class=\"jt-related\">Related products: <a href=\"https:\/\/jutrion.com\/pv-combiner-box\/\">PV combiner box<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/dc-mccb\/\">DC MCCB<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/spd\/\">SPD<\/a><\/p>\n    <\/div>\n\n    <div class=\"jt-std\"><strong>Standards referenced<\/strong>IEC 60364-7-712 (PV systems) \u00b7 IEC 62548 (PV array design) \u00b7 module &amp; inverter datasheet limits.<\/div>\n    <p class=\"jt-fine\">Estimate for guidance only. Final string sizing must use the module and inverter datasheet values, the site&#8217;s lowest expected temperature, and be verified by a qualified person.<\/p>\n  <\/div>\n<\/div>\n\n<script>\n(function(){\n  var $=function(id){return document.getElementById(id);};\n  var voc=$('jt-voc'),beta=$('jt-beta'),tmin=$('jt-tmin'),vmax=$('jt-vmax'),mods=$('jt-mods'),\n      cvocEl=$('jt-cvoc'),maxEl=$('jt-max'),strEl=$('jt-str'),chk=$('jt-chk');\n  function calc(){\n    var V=parseFloat(voc.value),b=parseFloat(beta.value),T=parseFloat(tmin.value),Vm=parseFloat(vmax.value),n=parseInt(mods.value,10);\n    if(!(V>0)||isNaN(b)||isNaN(T)){cvocEl.textContent='\u2014';maxEl.textContent=strEl.textContent='\u2014';chk.className='jt-pill na';chk.textContent='\u2014';return;}\n    var cv=V*(1+(b\/100)*(T-25));\n    cvocEl.textContent=cv.toFixed(1);\n    if(Vm>0){var mx=Math.floor(Vm\/cv);maxEl.textContent=mx+' modules';}else maxEl.textContent='\u2014';\n    if(n>0){var sv=n*cv;strEl.textContent=sv.toFixed(0)+' V';\n      if(Vm>0){var pass=sv<=Vm;chk.className='jt-pill '+(pass?'ok':'no');chk.textContent=pass?('OK \u2014 '+sv.toFixed(0)+' V \u2264 '+Vm+' V'):('EXCEEDS '+Vm+' V \u2014 reduce modules');}\n      else{chk.className='jt-pill na';chk.textContent='enter inverter limit';}}\n    else{strEl.textContent='\u2014';chk.className='jt-pill na';chk.textContent='enter modules';}\n  }\n  [voc,beta,tmin,vmax,mods].forEach(function(el){el.addEventListener('input',calc);el.addEventListener('change',calc);});\n  $('jt-copy').addEventListener('click',function(){var b=$('jt-copy');var txt='Module Voc(STC): '+voc.value+' V, \u03b2 '+beta.value+' %\/\u00b0C, Tmin '+tmin.value+' \u00b0C\\nCold Voc\/module: '+cvocEl.textContent+' V\\nMax modules\/string: '+maxEl.textContent+'\\nString cold Voc: '+strEl.textContent+'\\nCheck: '+chk.textContent;navigator.clipboard.writeText(txt).then(function(){var o=b.textContent;b.textContent='Copied \u2713';setTimeout(function(){b.textContent=o;},1500);}).catch(function(){b.textContent='Press Ctrl+C';});});\n  calc();\n})();\n<\/script>\n<!-- ===== end block ===== -->\n\n","protected":false},"excerpt":{"rendered":"<p>Solar &amp; DC PV String Voltage Calculator (Cold Voc &amp; Max Modules) Find the worst-case cold open-circuit voltage of a PV string and the maximum number of modules that stays within the inverter&#8217;s DC voltage limit. Cold mornings \u2014 not hot afternoons \u2014 set the highest string voltage, and exceeding the inverter limit can destroy [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1778,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1798","page","type-page","status-publish","hentry"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1798","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/comments?post=1798"}],"version-history":[{"count":1,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1798\/revisions"}],"predecessor-version":[{"id":1799,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1798\/revisions\/1799"}],"up":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1778"}],"wp:attachment":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/media?parent=1798"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}