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Engineering-grade inverter-to-panel AC cable design: full load current, ampacity derating, voltage drop, I²R loss and short-circuit withstand verified against IEC, NEC and IS methodology.
Inputs
1
Inverter & system parameters
The cable carries the inverter's continuous rated output for thousands of hours a year, so design current is taken at full rated output — not at an average load.
Affects cable reactance used in the voltage-drop check
2
Cable construction
Conductor material fixes resistivity and short-circuit constant k; insulation fixes the permitted conductor temperature and therefore the base ampacity.
Cables electrically in parallel, same size and length
3
Installation & environment
Ampacity is a thermal limit. Anything that slows heat dissipation — hot air, poor soil, deep burial, grouped circuits — reduces the current the cable may carry.
Buried installations only — IEC Table B.52.16 uses 2.5 K·m/W as its reference condition
Buried installations only
Independent circuits sharing the route — not the parallel runs of one circuit
Clear distance between adjacent cables in the same trench. Enter the actual installed spacing. Typical values: 0, 25, 50, 75, 100, 125, 250, 500 mm.
4
Route & design criteria
Voltage drop and short-circuit withstand are separate verifications; a cable that passes ampacity can still fail either of them on a long route or a stiff grid.
How to use this calculator: AC Cable Sizing Calculator
Use this page to screen an inverter AC feeder against four independent constraints: continuous ampacity, voltage drop, power loss and adiabatic short-circuit withstand. The example below is calculated by this page's real engine from the displayed inputs.
1Confirm that the AC Cable Sizing Calculator matches the quantity or design check you need.
2Enter Inverter rated output power, System voltage (line-to-line), and Power factor using the units printed beside each field.
3Select the applicable System type, System frequency, and Conductor material options; these choices change the calculation method or factors.
4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.
Input guide and example values
Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.
Input
Example value
Why it matters
Inverter rated output power
250 kW
Measured or known inverter rated output power used by the calculation engine.
System voltage (line-to-line)
800 V
Measured or known system voltage (line-to-line) used by the calculation engine.
System type
Three phase
Select the option that matches the real installation or scenario.
System frequency
50 Hz
Affects cable reactance used in the voltage-drop check
Power factor
0.98
Measured or known power factor used by the calculation engine.
Conductor material
Aluminium
Select the option that matches the real installation or scenario.
Cable insulation
XLPE — 90 °C conductor
Select the option that matches the real installation or scenario.
Parallel runs per phase
1
Cables electrically in parallel, same size and length
Installation method
Direct buried in soil
Select the option that matches the real installation or scenario.
Ambient temperature
45 °C
Measured or known ambient temperature used by the calculation engine.
Soil thermal resistivity
1.5 K·m/W
Buried installations only — IEC Table B.52.16 uses 2.5 K·m/W as its reference condition
Burial depth
0.8 m
Buried installations only
Number of grouped circuits
3
Independent circuits sharing the route — not the parallel runs of one circuit
Installation grouping
Same trench — spaced cables
Select the option that matches the real installation or scenario.
Cable-to-cable clear spacing
75 mm
Clear distance between adjacent cables in the same trench. Enter the actual installed spacing. Typical values: 0, 25, 50, 75, 100, 125, 250, 500 mm.
Cable arrangement
Multicore cables
Select the option that matches the real installation or scenario.
Cable route length (one way)
80 m
Measured or known cable route length (one way) used by the calculation engine.
Maximum allowable voltage drop
2 %
Measured or known maximum allowable voltage drop used by the calculation engine.
Available short circuit current
25 kA
Measured or known available short circuit current used by the calculation engine.
Protection clearing time
0.2 s
Measured or known protection clearing time used by the calculation engine.
Formula, derivation and worked example
This OneCalcApp tool follows the full engineering workflow used by solar EPC design teams: design inputs, full load current, preliminary conductor selection on ampacity, derating for ambient temperature, soil thermal resistivity, burial depth, grouping and installation method, then verification of voltage drop, I²R power loss and short-circuit thermal withstand. A conductor is only recommended when every one of those checks passes; if any check fails the calculator escalates to the next standard cross-section, or adds the parallel runs you specify. Every intermediate value is shown so the result can be verified by hand against the same formulas.
The design current is obtained from three-phase real power, I = P/(√3 V cos φ). A reference ampacity is then corrected for the actual thermal environment. The calculator reports those multipliers separately so K1/K2/K3/K4 are not hidden inside one unexplained factor.
In IEC terminology used by the cited guide, K1 is the ambient-air temperature factor from Table B.52.14, K2 is the ground-temperature factor from Table B.52.15, K3 is the soil thermal-resistivity factor from Table B.52.16, and K4 is the circuit-grouping factor from Tables B.52.17/B.52.18. Only the factors relevant to the selected installation are applied.
After ampacity, the same candidate conductor is checked using hot-conductor resistance for voltage drop and I²R loss, then A ≥ I√t/k for short-circuit withstand. The recommended size is the first listed size that passes every mandatory check, not merely the ampacity check.
11. Step 5a — Resistivity at operating temperature
ρ_T = ρ₂₀[1 + α(90 − 20)]
= 0.03616 Ω·mm²/m
12. Step 5b — Voltage drop
ΔV = √3 × I × L × (R cos φ + X sin φ) / runs
= 6.43 V = 0.8 % → PASS
13. Step 6 — Cable power loss
P_loss = 3 × I² × ρ_T × L / (A × runs)
= 1.961 kW (0.78 % of rated output)
14. Step 7 — Short circuit thermal withstand
A_min = I_sc √t / k = 25kA × √0.2 / 94
= 118.9 mm² ≤ 150 mm² → PASS
15. Step 8 — Final recommendation
all checks satisfied simultaneously
= 150 mm² Aluminium, XLPE (90 °C) — ACCEPTED
Computed example results
Recommended cable size
150 mm² Aluminium
XLPE (90 °C), 3½/4-core, direct buried in soil
Full load current
184.1 A
Base ampacity
270 A
at reference condition
Grouping / spacing factor
0.725
3 cable(s) per trench at 75 mm clear spacing
Overall derating factor
0.683
Corrected ampacity
184.4 A
≥ full load current
Voltage drop
6.43 V (0.8 %)
limit 2 %
Cable power loss
1.961 kW
0.78 % of rated output
Short circuit minimum area
118.9 mm²
k = 94, t = 0.2 s
Suggested protective device
250 A
≥ 1.25 × full load current
Overall design status
✅ ACCEPTED
Understanding the result
Read the main result together with supporting checks, assumptions, limits and intermediate values.
For a manual check, repeat the first equation, confirm the units and change one input at a time.
Common mistakes when using AC Cable Sizing Calculator
Do not mix units for Inverter rated output power (kW), System voltage (line-to-line) (V), Ambient temperature (°C). A unit mismatch changes the input magnitude even when the typed number looks reasonable.
Do not leave System type on the default choice unless that choice matches the real scenario; the selected option can change the calculation path or factor.
Do not replace the displayed I_FL = P × 1000 / (√3 × V × cos φ) three phase relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
Do not treat Recommended cable size = 150 mm² Aluminium from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.
When the AC Cable Sizing Calculator is useful
AC Cable Sizing Calculator is designed for cases where Inverter rated output power, System voltage (line-to-line), System type, System frequency are known and you need Recommended cable size, Full load current, Base ampacity. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.
Use the calculator for the scope described by its inputs and notes. The displayed method is I_FL = P × 1000 / (√3 × V × cos φ) three phase. If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.
Inverter rated output power and System voltage (line-to-line): what changes the answer
The worked example uses Inverter rated output power = 250 kW, System voltage (line-to-line) = 800 V, System type = Three phase, System frequency = 50 Hz. With those values, Recommended cable size is 150 mm² Aluminium. Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.
For this calculator, the main input roles are: Inverter rated output power (kW): Measured or known inverter rated output power used by the calculation engine. System voltage (line-to-line) (V): Measured or known system voltage (line-to-line) used by the calculation engine. System type: Select the option that matches the real installation or scenario. Available choices include Three phase, Single phase. System frequency: Affects cable reactance used in the voltage-drop check Available choices include 50 Hz, 60 Hz.
How to sanity-check a AC Cable Sizing Calculator result
Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Recommended cable size, because it is the first worked-example output shown by the live engine.
Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.
Next logical calculator
Continue with Cable Sizing Calculator
Useful next check because both tools use Power factor and Conductor material, while Cable Sizing Calculator answers a different part of the same workflow.
Temperature and soil-resistivity factors are conservative lookups from the cited IEC 60364-5-52 tables: when an input falls between published rows, the next more adverse listed condition is used.
Buried grouping factors use the Table B.52.18 spacing grid; spacing between published columns is linearly interpolated and circuit counts above the reproduced rows are a screening extrapolation. Treat that extrapolated K4 as an estimate and verify an issued design with the current licensed standard or IEC 60287.
The burial-depth, installation-method and phase-formation multipliers, and the indicative base-ampacity arrays, are screening-model assumptions rather than verbatim IEC table values. Replace them with the selected cable manufacturer's rating data and the exact project installation method before construction.
IEC guidance notes that the soil factors are averaged to about ±5%, assume uniform soil, and do not cover local drying. Use IEC 60287 or manufacturer software where soil drying, deep burial or high grouping materially affects the design.
This OneCalcApp tool follows the full engineering workflow used by solar EPC design teams: design inputs, full load current, preliminary conductor selection on ampacity, derating for ambient temperature, soil thermal resistivity, burial depth, grouping and installation method, then verification of voltage drop, I²R power loss and short-circuit thermal withstand. A conductor is only recommended when every one of those checks passes; if any check fails the calculator escalates to the next standard cross-section, or adds the parallel runs you specify. Every intermediate value is shown so the result can be verified by hand against the same formulas.
Engineering notes
High ambient temperatures reduce cable current carrying capacity — a 45 °C site can lose a quarter of the published rating.
Voltage drop directly affects inverter efficiency, and long cable routes may require larger conductor sizes than ampacity alone suggests.
Short circuit verification ensures the cable survives until protection operates; it is a thermal check, not a current-rating check.
Grouped circuits heat one another. Derating for grouping is often the single largest correction in a solar plant trench.
Power loss is paid for every operating hour of the plant's 25-year life, so the economic optimum conductor is often one size above the minimum.
Formulas explained
I_FL = P × 1000 / (√3 × V × cos φ)
Full load current is the starting point of every cable design. The inverter exports its rated kW continuously in good irradiance, so the conductor must carry this current indefinitely without exceeding its permitted temperature.
I_FL
Full load (design) current in amperes — the continuous current the cable must carry.
P
Inverter rated AC output power in kW, multiplied by 1000 to convert to watts.
V
System line-to-line voltage in volts at the inverter AC terminals.
cos φ
Power factor. A lower power factor raises current for the same real power.
√3
Balanced three-phase factor (1.732). It is replaced by 1 for a single-phase system.
Never size on average or seasonal output. Sizing on rated output is what IEC 60364 and NEC 690 continuous-duty rules require.
Published ampacity applies to one reference condition only. Real installations are hotter, deeper, more crowded or in poorer soil, so the rated value must be corrected before it can be compared with the design current.
I_z(base)
Ampacity of the conductor at the reference condition (30 °C in air, 20 °C in ground).
k_amb
Ambient or soil temperature correction, from the permitted conductor temperature.
Burial depth correction — deeper cables shed heat more slowly.
k_group
Grouping correction for adjacent circuits heating each other.
k_method
Installation method correction for ducts, conduits, trays and direct burial.
n
Number of parallel runs per phase carrying the current.
Derating is multiplicative. Four modest factors of 0.9 together give 0.66 — roughly a one-third loss of capacity.
K1 or K2 = conservative lookup at the selected air or ground temperature
IEC 60364-5-52 publishes different temperature factors for cables in air and cables in the ground. The calculator selects Table B.52.14 (K1) for air or Table B.52.15 (K2) for buried installations and uses the next hotter listed row when the entered temperature falls between rows.
K1
Ambient-air temperature factor from IEC 60364-5-52 Table B.52.14; reference air temperature 30 °C.
K2
Ground-temperature factor from IEC 60364-5-52 Table B.52.15; reference ground temperature 20 °C.
PVC / XLPE
Insulation column selected because the permitted conductor temperatures differ.
These are table lookups, not values generated by a square-root approximation. XLPE and PVC must use their own columns.
ΔV = √3 × I × L × (R cos φ + X sin φ)
Voltage drop determines whether the inverter can export at its rated power without approaching its grid over-voltage trip point. Reactance is included because on larger conductors the inductive component becomes comparable to resistance.
ΔV
Line-to-line voltage drop in volts over the route.
I
Full load current per the earlier calculation.
L
One-way route length in metres — not the loop length for three-phase.
R
AC resistance per metre, ρ_T / A, with resistivity corrected to operating temperature.
X
Reactance per metre, typically about 0.08 mΩ/m for LV multicore cable.
cos φ, sin φ
Power factor and its sine, weighting the resistive and reactive contributions.
IEC 60364-5-52 practice keeps the total installation drop within about 5%; solar EPC specifications usually demand 1–2% on the inverter AC feeder alone.
ρ_T = ρ₂₀ × [1 + α (T_op − 20)]
Conductor resistance rises with temperature. Sizing at 20 °C resistivity understates both voltage drop and power loss for a cable that actually runs at 70–90 °C.
ρ₂₀
Resistivity at 20 °C — 0.0172 Ω·mm²/m copper, 0.0282 Ω·mm²/m aluminium.
α
Temperature coefficient of resistance, about 0.00393/K copper and 0.00403/K aluminium.
T_op
Assumed operating conductor temperature, taken as the insulation limit for a conservative design.
Using the hot resistivity is the conservative engineering choice and is what IEC 60287 assumes for loss calculations.
P_loss = 3 × I² × R_total
Cable loss is dissipated as heat every operating hour and is a permanent deduction from plant yield. It is the economic half of cable sizing: a larger conductor costs once, losses cost every year.
P_loss
Total three-phase copper loss in the cable, in watts or kW.
I
Full load current per phase.
R_total
Resistance of one phase conductor over the full route, ρ_T × L / (A × n).
3
Three current-carrying phase conductors; use 2 for a single-phase circuit.
As a design target, keep the inverter feeder loss below roughly 1% of rated power; beyond that the payback on a larger conductor is usually immediate.
A_min = I_sc × √t / k
During a fault the cable carries many times its rated current for a short time. The adiabatic equation checks that the conductor cross-section is large enough for the insulation to survive until the protection clears the fault.
A_min
Minimum conductor cross-section for short-circuit withstand, in mm².
I_sc
Prospective RMS short-circuit current at the cable, in amperes.
t
Protection operating time in seconds, including breaker opening time.
k
Material and insulation constant: about 143 Cu/XLPE, 115 Cu/PVC, 94 Al/XLPE, 76 Al/PVC.
This is the adiabatic method of IEC 60364-4-43 with fault levels from IEC 60909. Slow protection settings can drive the cable size more than the load current does.
What is ampacity?
Ampacity is the maximum continuous current a conductor can carry without its temperature exceeding the limit set by its insulation — 70 °C for PVC and 90 °C for XLPE. It is a thermal limit, not an electrical one: the current itself does no harm, but the I²R heat it generates must escape into the surrounding air, duct or soil faster than it is produced. Published ampacity always refers to one specific reference condition, typically a single circuit in free air at 30 °C or buried at 20 °C in soil of 1.2 K·m/W thermal resistivity. Any real installation that is hotter, deeper, more crowded or in drier soil dissipates heat less effectively, so the published figure must be corrected downwards before it is compared with the design current. Sizing a cable on ampacity alone is never sufficient, but a cable that fails ampacity is unsafe regardless of how well it performs on every other check.
What is voltage drop?
Voltage drop is the difference between the voltage at the sending end of a cable and the voltage at the receiving end, caused by the conductor's resistance and reactance carrying load current. In a solar plant the flow is reversed: the inverter pushes current towards the panel, so the inverter terminal voltage rises above the panel voltage by the amount of the drop. That matters because grid-tied inverters must disconnect when their terminal voltage exceeds the statutory limit, so an undersized AC feeder causes nuisance over-voltage tripping on exactly the sunny days that should generate the most energy. Voltage drop also represents real energy converted to heat. IEC 60364-5-52 practice limits the total installation drop to a few percent, while solar EPC specifications commonly demand 1–2% on the inverter feeder alone. Because drop is proportional to route length, long runs frequently force a conductor larger than ampacity requires.
What is derating?
Derating is the systematic reduction of a cable's published current rating to account for installation conditions that are worse than the reference condition the rating was published for. Five corrections dominate practical solar work: ambient air or soil temperature, soil thermal resistivity, burial depth, the number of grouped circuits, and the installation method itself. Each correction is a factor below or near unity and they multiply together, so several individually mild factors can combine into a severe reduction — four factors of 0.9 give an overall factor of 0.66, meaning a third of the nameplate capacity has been lost. Derating is where inexperienced designs most often go wrong, because the correction is invisible in a datasheet and only appears as a slowly degrading, overheating cable years later. OneCalcApp displays each correction factor separately so the engineer can see exactly which condition is driving the derating and whether it can be improved by changing the route or trench layout.
What is cable power loss?
Cable power loss is the electrical energy converted to heat inside the conductor, equal to I²R in each current-carrying core — three times that value for a balanced three-phase circuit. Because loss varies with the square of current, it is dominated by full-output operation, and because conductor resistance rises with temperature a hot cable loses more than a cold one carrying the same current. Over the twenty-five-year life of a solar plant, feeder losses represent a significant quantity of energy that was generated but never sold, which is why cable sizing is an economic optimisation and not merely a safety exercise. A common engineering target is to keep inverter feeder loss below about 1% of rated power. Increasing the conductor by one standard size typically reduces loss in inverse proportion to the cross-section, and the additional cable cost is frequently recovered within the first few years of operation.
What is short circuit withstand?
Short-circuit withstand is the ability of a cable to survive the enormous current that flows during a fault for the short time before protection clears it. The fault current may be twenty or more times the rated current, and no heat escapes to the surroundings in that fraction of a second, so the process is treated as adiabatic: all the energy stays in the conductor and raises its temperature almost instantly. The adiabatic equation A ≥ I√t / k compares the conductor cross-section with the let-through energy of the fault, where k depends on the conductor material and the insulation's permitted short-circuit temperature. If the conductor is too small the insulation melts, the cable is destroyed, and the fault can escalate into a fire even though protection operated correctly. This check is frequently the deciding constraint on stiff systems with high fault levels or where protection settings are deliberately slow for coordination.
Why the checks must all pass together
Professional cable sizing is a sequence of independent verifications, not a single formula. Current carrying capacity verifies thermal loading during normal operation; voltage drop verifies electrical performance and inverter compatibility; power loss evaluates long-term efficiency and economics; short-circuit withstand verifies survival during a fault; and the installation method determines whether the assumed heat dissipation is realistic. A conductor is only acceptable when all of them are satisfied simultaneously, which is why a design that looks generous on ampacity can still be rejected on voltage drop over a long route, or on short-circuit withstand near a large transformer. OneCalcApp follows internationally accepted engineering methodology for educational and design assistance, presenting each check separately with an explicit PASS or FAIL so that engineers can verify manual calculations quickly and see immediately which constraint is governing the final conductor size.
Worked example
1250 kW inverter, 800 V three phase, power factor 0.98, aluminium XLPE cable.
2I_FL = 250 000 / (1.732 × 800 × 0.98) = 184 A.
3Direct buried at 45 °C, soil 1.5 K·m/W, 0.8 m deep, 3 grouped circuits → overall derating ≈ 0.66.
4A 95 mm² aluminium conductor rated 164 A derates to about 108 A — it fails, so the calculator escalates.
5185 mm² aluminium derates to about 162 A, passes ampacity, holds voltage drop under 2% over 80 m and clears the adiabatic short-circuit check at 25 kA for 0.2 s.
Assumptions
Balanced three-phase load with the inverter exporting at its rated continuous output.
Conductor operating temperature is taken at the insulation limit (90 °C XLPE, 70 °C PVC) for resistance, voltage drop and loss — the conservative case.
Reactance is taken as a typical LV multicore value of about 0.08 mΩ/m; for large conductors or long routes confirm against the manufacturer's mV/A/m data.
Base ampacities are indicative engineering values for a single circuit at the reference condition, not a reproduction of any standard's tables.
Derating factors follow the published thermal relationships; project specifications may impose stricter values.
Tips
If ampacity is the governing constraint, improving the trench (better backfill, wider spacing, shallower depth) is often cheaper than a larger conductor.
If voltage drop governs, consider relocating the inverter or the panel before buying copper — drop is proportional to route length.
Parallel runs share current but need identical length, size and routing, and each run needs its own derating for the added grouping.
Where the calculated loss exceeds about 1% of rated power, price one size up against twenty-five years of lost generation.
Aluminium is the economic default at utility scale; copper wins where space, terminations or short-circuit withstand are tight.
Warnings
Never size an AC feeder on current carrying capacity alone — voltage drop and short-circuit withstand must both be verified.
Slow or deliberately delayed protection settings raise the minimum conductor size through the adiabatic check; confirm the actual clearing time with the protection engineer.
Aluminium terminations require bi-metallic lugs, correct torque and periodic re-checking; poor terminations, not the conductor, cause most aluminium failures.
Results are for design assistance and education; the final design must be approved by a qualified electrical engineer against the project specification and local code.
IEC 60287 — Calculation of the continuous current rating of cables (thermal methodology)
IEC 60502 — Power cables with extruded insulation for 1 kV to 30 kV
IEC 60909 — Short-circuit currents in three-phase AC systems
IEC 61439 — Low-voltage switchgear and controlgear assemblies
NEC Article 310 — Conductors for general wiring and ampacity adjustment
NEC Article 240 — Overcurrent protection
NEC Article 300 — General requirements for wiring methods
NEC Article 690 — Solar photovoltaic systems
NEC Article 705 — Interconnected electric power production sources
IS 3961 — Recommended current ratings for cables
IS 7098 — Crosslinked polyethylene insulated cables
IS 1255 — Code of practice for installation and maintenance of power cables
IS 3043 — Code of practice for earthing
Frequently asked questions
How do I calculate the full load current of a solar inverter?+
For a three-phase inverter, I = P × 1000 / (√3 × V × cos φ), where P is the rated AC output in kW, V the line-to-line voltage and cos φ the power factor. A 250 kW inverter at 800 V and 0.98 power factor draws about 184 A. For a single-phase inverter drop the √3 factor.
Why must cable ampacity be derated?+
Published ampacity applies to one reference condition — usually a single circuit in free air at 30 °C or buried at 20 °C in 1.2 K·m/W soil. Higher ambient temperature, poorer soil, deeper burial and grouped circuits all slow heat dissipation, so the rating must be multiplied by correction factors before being compared with the design current.
What is a typical overall derating factor for a buried solar feeder?+
In hot climates with grouped circuits it is commonly between 0.6 and 0.75. Because the individual factors multiply, four modest corrections of 0.9 each already give 0.66, so about a third of the nameplate ampacity is unavailable.
What voltage drop is acceptable on an inverter AC cable?+
IEC 60364-5-52 practice keeps the total installation drop within roughly 5%, but solar EPC specifications usually limit the inverter feeder alone to 1–2%. Tight limits protect against inverter over-voltage tripping and reduce energy losses.
Why does voltage drop cause inverter tripping?+
When the inverter exports, current flows towards the grid and the inverter terminal voltage rises above the panel voltage by the cable drop. If the point of connection is already near the upper statutory limit, the extra rise pushes the inverter past its over-voltage threshold and it disconnects, losing generation on the sunniest days.
Should reactance be included in the voltage drop calculation?+
Yes for conductors above roughly 95–120 mm², where reactance of about 0.08 mΩ/m becomes comparable with resistance. Ignoring it understates the drop on large cables. This calculator includes both the resistive and reactive components weighted by the power factor.
How is cable power loss calculated?+
For a balanced three-phase circuit, P_loss = 3 × I² × R, where R is the resistance of one phase conductor over the full route at operating temperature. Loss varies with the square of current, so it is dominated by full-output operation.
How much cable loss is acceptable in a solar plant?+
A common engineering target is below about 1% of the inverter rated power for the AC feeder. Above that, the value of the energy lost over a twenty-five-year life usually exceeds the cost of the next conductor size.