PV Cable Voltage Drop Calculator
Compare 4mm², 6mm² and 10mm² solar DC cable in one calculation. Enter your run length, string current and voltage — get drop percentages against common PV project targets and a copyable spec for RFQ.
OmniSol sources and coordinates H1Z2Z2-K cable per EN 50618 / IEC 62930 from TÜV-certified manufacturers for 1000V and 1500V DC projects worldwide.
Cable Run Parameters
Distance from string to combiner or inverter (positive conductor only — total path is 2×)
Use Imp for energy loss estimate; use Isc for conservative worst-case
Use Vmp for realistic loss %; Voc gives a conservative baseline
20°C = IEC 60228 reference. 70°C / 90°C = typical PVC or XLPE rated conductor working temperature — resistance increases 19–27%
Cable Resistance Reference
IEC 60228 base resistance at 20 °C, corrected to selected conductor temperature (α = 0.00393/°C for copper). Confirm actual resistance from supplier cable datasheet.
Enter your cable run parameters and click Calculate
Results compare 4mm², 6mm² and 10mm² cable simultaneously
4mm²
4.61 mΩ/m
6mm²
3.08 mΩ/m
10mm²
1.83 mΩ/m
PV Cable Products from OmniSol
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Frequently Asked Questions
What voltage drop is acceptable for solar DC string cables?
≤1% is a common PV project engineering target for string cable runs — it represents minimal energy loss. ≤2% is within typical project tolerance but means measurable annual yield reduction. Values above 2% are generally considered high and justify upgrading to a larger cross-section. These are project targets, not mandatory IEC voltage-drop limits.
Should I use Isc or Imp for this calculation?
Use Imp (maximum power current) for energy loss estimation — it reflects real operating conditions at MPPT. Use Isc for a conservative worst-case check. The difference is typically 5–10%. Both are valid depending on whether accuracy or safety margin is the priority.
What is the PV DC voltage drop formula?
ΔV = 2 × L × I × R, where L is one-way cable length in meters, I is current in amps, and R is cable resistance in ohms per meter (e.g., 0.00308 Ω/m for 6mm² copper at 20 °C per IEC 60228 reference values). The factor 2 accounts for both positive and negative conductors. Percentage drop = ΔV ÷ V_string × 100.
Why is 6mm² often preferred over 4mm² for residential PV strings?
6mm² has 33% lower resistance than 4mm² (3.08 vs 4.61 mΩ/m), giving significantly lower voltage drop on runs over 30–40 m. It also provides more thermal margin. The cost premium is modest compared to the yield improvement over a 25-year system life.
Does OmniSol supply H1Z2Z2-K PV cable?
Yes. OmniSol sources and coordinates H1Z2Z2-K solar DC cable per EN 50618 / IEC 62930 in 4mm², 6mm², and 10mm² from TÜV-certified manufacturers. Contact us with your cable schedule for a BOM-ready RFQ response.
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