{"id":1794,"date":"2026-07-27T10:33:50","date_gmt":"2026-07-27T02:33:50","guid":{"rendered":"https:\/\/jutrion.com\/?page_id=1794"},"modified":"2026-08-07T10:55:05","modified_gmt":"2026-08-07T02:55:05","slug":"calculateur-de-fusible-de-chaine-photovoltaique","status":"publish","type":"page","link":"https:\/\/jutrion.com\/fr\/tools\/pv-string-fuse-calculator\/","title":{"rendered":"PV String Fuse Rating Calculator"},"content":{"rendered":"\n<!-- ===== JUTRION PV String Fuse Rating 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 Fuse Rating Calculator (gPV)<\/h1>\n  <p class=\"tool-lede\">Find the allowable gPV string-fuse rating window from the module short-circuit current and the module&#8217;s maximum series-fuse rating, and see when string fuses are actually needed. A string fuse protects a module string against reverse current from the other paralleled strings \u2014 sized above the normal current but below what the module can withstand.<\/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-isc\">Module I<sub>sc<\/sub> at STC (A)<\/label><input type=\"number\" id=\"jt-isc\" value=\"13.8\" min=\"0.1\" step=\"0.1\" inputmode=\"decimal\"><\/div>\n        <div class=\"jt-field\"><label for=\"jt-n\">Parallel strings<\/label><input type=\"number\" id=\"jt-n\" value=\"4\" min=\"1\" step=\"1\" inputmode=\"numeric\"><\/div>\n      <\/div>\n      <div class=\"jt-field\"><label for=\"jt-max\">Module max series fuse rating (A)<\/label><input type=\"number\" id=\"jt-max\" value=\"25\" min=\"1\" step=\"1\" inputmode=\"numeric\"><\/div>\n      <div class=\"jt-field\"><label for=\"jt-mult\">Sizing rule (lower bound)<\/label>\n        <select id=\"jt-mult\"><option value=\"1.5\" selected>1.5 \u00d7 Isc (IEC 60364-7-712)<\/option><option value=\"1.56\">1.56 \u00d7 Isc (NEC 1.25\u00d71.25)<\/option><\/select>\n      <\/div>\n      <div class=\"jt-note\"><span>\u24d8<\/span><span>Both I<sub>sc<\/sub> and the maximum series-fuse rating are on the module datasheet. The fuse rating must fall between the lower bound and the module&#8217;s maximum.<\/span><\/div>\n    <\/div>\n    <div class=\"jt-readout\">\n      <div><div class=\"jt-rl\">Recommended gPV fuse<\/div><div class=\"jt-big\"><span id=\"jt-rec\">\u2014<\/span> <span>A<\/span><\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">Minimum rating<\/div><div class=\"v\" id=\"jt-min\">\u2014<\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">Maximum rating<\/div><div class=\"v\" id=\"jt-maxv\">\u2014<\/div><\/div>\n      <div class=\"jt-rec\"><div class=\"k\">String fuse required?<\/div><div style=\"margin-top:6px\"><span class=\"jt-pill na\" id=\"jt-need\">\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>The sizing window<\/h2>\n    <div class=\"jt-eq\">Minimum In = 1.5 \u00d7 I<sub>sc<\/sub>   (lower bound, IEC 60364-7-712)\nMaximum In = min( 2.4 \u00d7 I<sub>sc<\/sub> , module max series fuse )\nChoose a standard gPV rating inside the window<\/div>\n    <p>The lower bound keeps the fuse from tripping on normal string current, which can exceed the STC value under high irradiance. The upper bound ensures the fuse still protects the module \u2014 it must clear before the reverse current from the other strings exceeds what the module can safely carry, and it can never be rated above the module&#8217;s stated maximum series fuse.<\/p>\n\n    <h2>When is a string fuse needed?<\/h2>\n    <p>String fuses guard against <b>reverse current<\/b>: if one string faults, the healthy paralleled strings feed current back into it. With only a few strings the combined reverse current stays within the module&#8217;s withstand and no fuse is required. As the number of parallel strings grows, the reverse current rises until protection becomes necessary \u2014 commonly from about <b>three or more strings in parallel<\/b>, but the exact threshold follows the module&#8217;s maximum reverse-current rating per IEC 62548.<\/p>\n    <div class=\"jt-note\"><span>\u26a0<\/span><span><b>Use gPV fuses, not ordinary fuses.<\/b> gPV fuses (IEC 60269-6) are rated for the full DC string voltage and the low-overcurrent, reverse-current duty of PV. A standard AC or gG fuse may not interrupt a DC PV fault safely.<\/span><\/div>\n\n    <h2>Frequently asked questions<\/h2>\n    <div class=\"jt-faq\">\n      <details><summary>Why is the minimum 1.5 \u00d7 Isc and not just Isc?<\/summary><p>Irradiance can exceed 1000 W\/m\u00b2 and reflections add current, so the real string current runs above the STC figure. The 1.5 factor keeps the fuse from nuisance-blowing under those conditions.<\/p><\/details>\n      <details><summary>What if my module max series fuse is below 1.5 \u00d7 Isc?<\/summary><p>Then no standard fuse fits the window, and string fusing by conventional means is not viable \u2014 the array must be arranged with fewer parallel strings, or protected by a different method. Re-check the module data.<\/p><\/details>\n      <details><summary>Do both ends of the string need a fuse?<\/summary><p>In a functionally earthed or floating array both polarities may need protection. Follow the array topology and IEC 62548 for whether one or both conductors are fused.<\/p><\/details>\n    <\/div>\n\n    <div class=\"jt-cta\">\n      <h2>Select the gPV fuse<\/h2>\n      <p>With the rating window and voltage set, match a gPV fuse and holder rated for the DC string voltage.<\/p>\n      <div class=\"jt-cta-btns\">\n        <a class=\"jt-btn\" href=\"https:\/\/jutrion.com\/fuse\/\">Explore JUTRION fuses<\/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\/fuse\/\">Fuse<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/pv-combiner-box\/\">PV combiner box<\/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, reverse current) \u00b7 IEC 60269-6 (gPV fuses).<\/div>\n    <p class=\"jt-fine\">Estimate for guidance only. The final fuse rating, voltage class, and the need for string protection must be confirmed by a qualified person against the module datasheet, the array topology, and IEC 62548.<\/p>\n  <\/div>\n<\/div>\n\n<script>\n(function(){\n  var $=function(id){return document.getElementById(id);};\n  var isc=$('jt-isc'),n=$('jt-n'),max=$('jt-max'),mult=$('jt-mult'),\n      recEl=$('jt-rec'),minEl=$('jt-min'),maxvEl=$('jt-maxv'),need=$('jt-need');\n  var GPV=[1,2,3,4,5,6,8,10,12,15,16,20,25,30,32,40,50];\n  function calc(){\n    var I=parseFloat(isc.value),N=parseInt(n.value,10),mx=parseFloat(max.value),m=parseFloat(mult.value);\n    if(!(I>0)){recEl.textContent='\u2014';minEl.textContent=maxvEl.textContent='\u2014';need.className='jt-pill na';need.textContent='\u2014';return;}\n    var lo=m*I, hi=Math.min(2.4*I,(mx>0?mx:Infinity));\n    minEl.textContent=lo.toFixed(1)+' A';\n    maxvEl.textContent=(isFinite(hi)?hi.toFixed(1)+' A':'\u2014');\n    var pick=null;for(var k=0;k<GPV.length;k++){if(GPV[k]>=lo&&GPV[k]<=hi){pick=GPV[k];break;}}\n    recEl.textContent=pick?pick:'none fits';\n    if(N>=3){need.className='jt-pill '+(pick?'ok':'no');need.textContent=pick?('Yes \u2014 '+N+' strings, use '+pick+' A gPV'):('Yes \u2014 but no standard rating fits');}\n    else{need.className='jt-pill na';need.textContent='Often not required at '+N+' string'+(N>1?'s':'');}\n  }\n  [isc,n,max,mult].forEach(function(el){el.addEventListener('input',calc);el.addEventListener('change',calc);});\n  $('jt-copy').addEventListener('click',function(){var b=$('jt-copy');var txt='Module Isc: '+isc.value+' A, '+n.value+' parallel strings, max series fuse '+max.value+' A\\nWindow: '+minEl.textContent+' \u2013 '+maxvEl.textContent+'\\nRecommended gPV fuse: '+recEl.textContent+' A\\nRequired: '+need.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 Fuse Rating Calculator (gPV) Find the allowable gPV string-fuse rating window from the module short-circuit current and the module&#8217;s maximum series-fuse rating, and see when string fuses are actually needed. A string fuse protects a module string against reverse current from the other paralleled strings \u2014 sized above the normal [&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-1794","page","type-page","status-publish","hentry"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1794","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=1794"}],"version-history":[{"count":1,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1794\/revisions"}],"predecessor-version":[{"id":1795,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1794\/revisions\/1795"}],"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=1794"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}