Solar Cable Size Calculator (Voltage Drop & Rise)
Find the right solar cable size in one calculation. Enter your run length, current and voltage to compare 4mm², 6mm² and 10mm² cable — get the voltage drop (called voltage rise on the inverter AC side in Australia) and a copyable spec for your 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.
How do I use a solar cable size calculator?
Enter the one-way run length, the string current (Imp for real operating loss, Isc for worst case), and the string voltage. The calculator returns the voltage drop for 4mm², 6mm² and 10mm² and flags the smallest size that meets the ≤1% target. "Wire" and "cable" are interchangeable for PV DC leads, so a solar wire size calculator works the same way.
What size solar cable do I need — 4mm² or 6mm²?
Short residential runs (under ~30 m round trip) usually stay within target on 4mm². For longer runs, higher current, or hot rooftops, 6mm² is the common choice; 10mm² is used for long C&I/utility runs or paralleled strings. Enter your run length and current above to see the exact drop for each size.
What is voltage rise, and can I use this as a solar voltage rise calculator?
Voltage rise is the Australian and New Zealand term for the voltage drop on the AC cable between the inverter and the main switchboard or grid connection point: because the inverter pushes power out, the voltage at the inverter rises above grid voltage. AS/NZS 4777.1 limits this rise to 2%. The formula is the same as for voltage drop on a single-phase circuit, so you can enter the inverter AC output current, the one-way cable length and 230 V to check it. For three-phase runs and larger AC cables, confirm with a full AS/NZS 3008 calculation.
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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