[{"data":1,"prerenderedAt":109},["ShallowReactive",2],{"example-system-voltage-en":3,"faq-system-voltage-en":71,"sources-system-voltage-en":105},{"input":4,"output":15},{"continuousPowerW":5,"cableCostPerMm2PerM":6,"peakPowerW":7,"cableLengthOneWayM":8,"maxDropPercent":9,"conductorMaterial":10,"conductorTempC":11,"inverterEfficiency":12,"standard":13,"legacy12VLoadW":14},1200,0.25,3000,4,3,"cu",30,0.9,"iec-60364",0,{"options":16,"recommendedVoltage":36,"areaRatio12to48":26,"steps":44,"warnings":54},[17,27,35],{"systemVoltage":18,"continuousCurrentA":19,"peakCurrentA":20,"requiredAreaMm2":21,"recommendedSize":22,"cableCost":25,"converterCost":14,"totalCost":25,"relativeArea":26},12,111.1111111111111,277.77777777777777,44.243385925925914,{"label":23,"areaMm2":24},"50 mm2",50,100,16,{"systemVoltage":28,"continuousCurrentA":29,"peakCurrentA":30,"requiredAreaMm2":31,"recommendedSize":32,"cableCost":34,"converterCost":14,"totalCost":34,"relativeArea":8},24,55.55555555555555,138.88888888888889,11.060846481481478,{"label":33,"areaMm2":26},"16 mm2",32,{"systemVoltage":36,"continuousCurrentA":37,"peakCurrentA":38,"requiredAreaMm2":39,"recommendedSize":40,"cableCost":42,"converterCost":14,"totalCost":42,"relativeArea":43},48,27.777777777777775,69.44444444444444,2.7652116203703696,{"label":41,"areaMm2":8},"4 mm2",8,1,[45,50],{"label":46,"expression":47,"value":26,"unit":48,"provenance":49},"areaScaling","A = 2 * rho * L * P \u002F (eta * U^2 * d%\u002F100)","","exact",{"label":51,"expression":52,"value":36,"unit":53,"provenance":49},"recommendedVoltage","min(C_cable + C_converter)","V",[55,61,66],{"level":56,"code":57,"params":58,"anchors":59},"info","CONSIDER_HIGHER_VOLTAGE",{},[60],"continuousPowerW",{"level":56,"code":62,"params":63,"anchors":65},"HIGH_CURRENT_LOW_VOLTAGE",{"current":64},111.1,[60],{"level":56,"code":67,"params":68,"anchors":70},"AMPACITY_SEPARATE_CHECK",{"required":69},27.78,[60],[72,75,78,81,84,87,90,93,96,99,102],{"q":73,"a":74},"Should I build my off-grid system at 12, 24 or 48 volts?","The calculator compares all three voltages on current, required conductor size and cost. It recommends not the electrically superior option but the one with the lowest total cost: if you already own 12 V appliances such as a compressor fridge, water pump and lighting, a 24 or 48 V bus forces a DC-DC converter, whose cost is set against the cable savings.",{"q":76,"a":77},"Why does the required cable size shrink so dramatically at higher voltage?","Cross-section scales with 1\u002FU², not 1\u002FU: the current falls with 1\u002FU, and at the same time the permissible absolute voltage drop grows with U because it is specified as a percentage of system voltage. From 12 V to 48 V that is a factor of 16. In the reference case — 1200 W over 4 m at 3 % — the requirements are 44.2 mm² at 12 V, 11.1 mm² at 24 V and 2.77 mm² at 48 V.",{"q":79,"a":80},"Does this calculator also check cable ampacity?","No — it checks voltage drop only, and it explicitly flags that ampacity is a separate check. Also outside its scope are the availability and price of specific appliances, DC-DC converter efficiency, battery block granularity, and national limits on DC voltages.",{"q":82,"a":83},"Why is the cross-section difference a factor of 16 and not 4?","Because two effects combine: at four times the voltage, a quarter of the current flows — AND the permissible absolute voltage drop (3% of U) is four times larger. Cross-section therefore scales with 1\u002FU². In the spec test case (1,200 W, 4 m, 3%): 44.2 mm² at 12 V, 11.1 mm² at 24 V, 2.77 mm² at 48 V — exactly 16:4:1. The area-true circles in the chart make this physically visible.",{"q":85,"a":86},"When is 12 V still the right choice?","When the device balance says so: compressor coolers, water pumps and lighting are cheapest and most varied as 12 V devices. Going to 24\u002F48 V requires a DC-DC converter for them — whose cost and losses enter the comparison. For small systems with short cables and many 12 V loads, 12 V wins the total-cost calculation despite thicker cables.",{"q":88,"a":89},"From when does a higher voltage become mandatory?","As a rule of thumb via current: from about 100 A continuous (≈ 1,200 W at 12 V) cables, fuses and terminals become unwieldy and expensive, and every joint becomes a heat source. A 3,000 W inverter at 12 V means over 250 A of peak current — there, 24 or 48 V is no longer a matter of taste. The calculator shows the currents per candidate directly in the columns.",{"q":91,"a":92},"Where does the cable price in the cost comparison come from?","It is a visible assumption with a market anchor: in August 2026, fine-stranded H07V-K copper cable retails around €0.26 per mm² and metre at 25 mm² and €0.19 at 50 mm² — larger sections are cheaper per mm². The default of €0.25 sits inside that range. Previously the value was fixed at €0.35 and unreachable through the form, although it decides half the recommendation.",{"q":94,"a":95},"When does 12 volts win despite the 16-fold cross-section?","When existing 12 V appliances would require a DC-DC converter. In the reference case (1,200 W, 4 m) the cables cost €100 at 12 V and €8 at 48 V — but 240 W of legacy 12 V loads plus a €150 converter flip the total: €100 versus €158. Exactly this counter-calculation is missing from rule-of-thumb articles that blanket-recommend 48 V.",{"q":97,"a":98},"Why does the cross-section scale with the square of the voltage?","Because two things change at once: current falls with 1\u002FU, and the permissible absolute voltage drop rises with U, since it is defined as a percentage of system voltage. From 12 to 48 V that is a factor of 4 × 4 = 16 — 44.2 mm² versus 2.77 mm² in the reference case. Looking at current alone, you expect a factor of 4 and are surprised.",{"q":100,"a":101},"Does this calculator also check the cable's ampacity?","No, deliberately not — it calculates voltage drop and says so in its own warning. Ampacity depends on installation method, grouping and ambient temperature and has its own calculator. Both checks must pass; the stricter one wins. At 12 V and 111 A, ampacity is almost always the tighter limit.",{"q":103,"a":104},"Does the calculator take values from the inverter calculator?","Yes: if you entered continuous and peak load there, both arrive pre-filled here — the chaining hands them over via the follow-on link. Conductor material (copper or aluminium), conductor temperature and efficiency are also adjustable since 5 August 2026; before that they existed in the calculation schema but were unreachable through the form.",[106],{"name":107,"url":-1,"retrievedAt":108,"version":-1},"Official publications of the standards bodies and state authorities (NFPA, IEC, DKE\u002FVDE, CEN)","2026-07-15",1786101725928]