Battery, energy & solar
Solar Cable Voltage Drop Calculator
Solar cable voltage drop equals current multiplied by round-trip cable resistance. Power lost in the cable equals current multiplied by that voltage drop.
Calculate resistive DC voltage drop and cable power loss between solar-system components.
Calculated result
Solar cable loss
Calculating…
Calculated locally in your browser
Planning math only. Verify equipment specifications and installation requirements separately.
What this calculator returns
Use the result for cable-loss planning only, then verify PV equipment limits and installation requirements.
Formula and variables
The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.
Vdrop = I × (2ρL/A); Ploss = I × Vdrop.
- Vdrop
- Voltage lost across the conductor path, in volts.
- I
- Current through the conductor, in amperes.
- R
- Electrical resistance of the modeled conductor path, in ohms.
- ρ
- Material resistivity at the modeled temperature, in ohm-metres.
- L
- Conductor length used by the selected path model.
- A
- Metal cross-sectional area of the conductor.
L is one-way cable length; the DC return path is included.
Worked example
| Input | Value |
|---|---|
| Circuit voltage | 48 V |
| Current | 20 A |
| One-way cable length | 30 ft |
| Conductor material | Copper |
| Result | At 48 V and 20 A, the tool calculates delivered voltage and watts lost for the selected two-conductor path. |
At 48 V and 20 A, the tool calculates delivered voltage and watts lost for the selected two-conductor path.
Reference table
| AWG | Cu 20°C Ω/1000 ft | Cu 75°C Ω/1000 ft | Al 20°C Ω/1000 ft | Al 75°C Ω/1000 ft | Cu 20°C Ω/km | Al 20°C Ω/km |
|---|---|---|---|---|---|---|
| 14 | 2.5254 | 3.0712 | 4.1400 | 5.0576 | 8.2853 | 13.5825 |
| 12 | 1.5882 | 1.9315 | 2.6036 | 3.1807 | 5.2107 | 8.5421 |
| 10 | 0.9988 | 1.2147 | 1.6374 | 2.0004 | 3.2770 | 5.3722 |
| 8 | 0.6282 | 0.7640 | 1.0298 | 1.2581 | 2.0609 | 3.3786 |
| 6 | 0.3951 | 0.4805 | 0.6476 | 0.7912 | 1.2961 | 2.1248 |
| 4 | 0.2485 | 0.3022 | 0.4073 | 0.4976 | 0.8152 | 1.3363 |
Frequently asked questions
Is this solar cable voltage-drop result code compliant?
No. PowerTotals performs transparent electrical math and planning estimates. Installation decisions must be checked against equipment documentation, the adopted code, and the authority having jurisdiction.
Are my inputs uploaded?
No. Calculations run locally in your browser, and analytics never receives raw electrical values.
Assumptions and limitations
- No PV code, ampacity, overcurrent, temperature-derating, connector, or protection sizing.
- Steady DC resistance model.
Method and sources
Read the calculation methodology, review the technical sources, or browse the reference table index. Last reviewed .