48V Wire Size Calculator

Forty-eight volts is the house-system voltage. A 3 kW inverter draws about 68 A from a 48 V bank against 272 A from a 12 V one, so the battery cable, the fuse and the busbars come down to sizes you can buy and bend, and a 3% budget is a full 1.44 V, which lets an array sit 40 ft from the controller on cable that would be hopeless at 12 V.

This is the solar cable size calculator set up for 48 V: the tool opens on the 48 V array-to-controller preset: 30 A over 40 ft at a 3% limit. Change anything you like; the tables below are fixed at 48 V.

Free download

Get the printable solar cable and fuse charts

DC cable ampacity with the ambient and bundling corrections, how far each size runs at 12, 24 and 48 V, PV string fuse sizes from Isc, and battery-to-inverter current by inverter size. Three pages, made to pin by the battery bank.

We store your email with EmailOctopus to send the charts and occasional solar sizing tips, nothing else. Unsubscribe any time. Privacy policy.

The three runs at 48 V

Every solar build has the same three DC legs. These are sized at the currents and lengths the calculator's own presets use, copper, 75°C conductor, 30°C ambient, three conductors, terminal rating per NEC 110.14(C). Change the current or the length and the answer moves; that is what the tool above is for.

Run Current One-way length Drop limit Copper size at 48 V Set by
Array to charge controller 30 A 40 ft 3% 6 AWG voltage drop (48 ft max)
Controller to battery 60 A 10 ft 2% 4 AWG ampacity (70 A at 60°C)
Battery to inverter 125 A 6 ft 2% 1 AWG ampacity (130 A at 75°C)

At 48 V ampacity takes over from voltage drop as the usual limit. The array run is still often drop-bound, because it is long, but the controller-to-battery and battery-to-inverter runs are short and heavy and are set by how much current the conductor can carry at its termination rating. NEC 110.14(C) caps circuits of 100 A or less at the 60°C column unless the equipment is marked otherwise, which is why a 60 A run needs 4 AWG here rather than the 6 AWG its 75°C ampacity would suggest.

Worked example

A 3,000 W inverter on 48 V draws about 68 A at nominal and about 78 A at the 42 V low-voltage cutoff, the figure to size on. Over a 6 ft run at a 2% limit that is 4 AWG copper at 60°C terminations, holding the drop near 0.5%, so ampacity and the lug size on the inverter decide it. The 4,000 W inverter in the inverter sizing example draws 104 A at the cutoff and steps up to 2 AWG at the 75°C column.

What each inverter size draws from a 48 V bank

The battery-to-inverter leg carries the highest current in the system, and it is sized on the current at the inverter's rated output and at the bank's lowest voltage, because that is the worst case the cable and the fuse have to survive. At 48 V nominal the low-voltage cutoff defaults to 42.0 V, which is 87.5% of nominal, and the inverter sizing calculator's own default efficiency is 92%.

DC input current, cable size and overcurrent device for each inverter rating on a 48 volt bank
Inverter DC amps at 48 V DC amps at 42.0 V cutoff Copper, 6 ft at 2% Device at 125%
2,000 W 45 A 52 A 6 AWG 70 A
3,000 W 68 A 78 A 3 AWG 100 A
5,000 W 113 A 129 A 1 AWG 175 A
8,000 W 181 A 207 A 4/0 AWG 300 A
10,000 W 226 A 259 A 300 kcmil 350 A

A 5,000 W inverter at 48 V draws less current than a 1,500 W one at 12 V. That is the whole reason house systems are built at 48 V: the cable, the fuse, the busbars and the disconnect are all ordinary parts at sizes you can buy anywhere, and the array can use the same voltage headroom on its own runs.

How far each cable runs at 48 V

Maximum one-way run in feet before voltage drop reaches 3% (1.44 V) on a 48 V DC circuit, copper. Greyed cells are currents the cable cannot carry at a 75°C termination, so length is moot. Design the battery-to-inverter leg to 2%, which is two thirds of these figures.

Maximum one-way run length in feet at 3 percent voltage drop on a 48 volt DC circuit, copper conductors, by current
Copper size 75°C ampacity 10 A 20 A 30 A 60 A 100 A 125 A
10 AWG 35 A 60 ft 30 ft 20 ft — — —
8 AWG 50 A 92 ft 46 ft 30 ft — — —
6 AWG 65 A 146 ft 73 ft 48 ft 24 ft — —
4 AWG 85 A 231 ft 115 ft 77 ft 38 ft — —
2 AWG 115 A 381 ft 190 ft 127 ft 63 ft 38 ft —
1/0 AWG 150 A 605 ft 302 ft 201 ft 100 ft 60 ft 48 ft
2/0 AWG 175 A 715 ft 357 ft 238 ft 119 ft 71 ft 57 ft
4/0 AWG 230 A 1,163 ft 581 ft 387 ft 193 ft 116 ft 93 ft

Resistances are NEC Chapter 9 Table 9 values; DC resistance is marginally lower, so these lengths are slightly conservative. Ampacities are NEC 310.16 for not more than three current-carrying conductors at 30°C, before the ambient and bundling corrections the calculator applies when you change those fields. For the drop on a run you already have, use the DC voltage drop calculator; to protect the run, the PV fuse and breaker calculator.

Frequently Asked Questions

What size wire do I need for a 48 V solar system?

It depends on the run, not the system. At 48 V the array-to-controller leg at 30 A over 40 ft needs 6 AWG copper, and the battery-to-inverter leg at 125 A over 6 ft needs 1 AWG. A 3% budget at 48 V is only 1.44 V, so the run length decides the array cable and the current decides the battery cable. Enter your own current and length in the calculator above.

How far can I run 10 AWG at 30 A on 48 V?

About 20 ft one-way before the drop reaches 3%, and about 13 ft at a 2% limit. Beyond that, step up one size per further increment of length; the run-length table above shows where each size gives out at 48 V.

Where is 48 V the right system voltage?

Off-grid homes, larger cabins, workshops and any system with a 3 kW or larger inverter or more than about 2 kW of array. Higher voltage means lower current for the same power, so the practical question is how much inverter you run: the DC current at the inverter's rating and at its low-voltage cutoff sets the battery cable and the fuse, and that number is what pushes bigger systems up to 24 V and 48 V.

Does this include ambient temperature and bundling derating?

The tables on this page do not; they are the NEC 310.16 base values at 30 C with three conductors. The calculator above does: change the ambient temperature and the conductor count and it applies the NEC 310.15(B)(1)(1) and 310.15(C)(1) factors, which matter on a hot roof or in an engine bay, and it caps the answer at the terminal rating per NEC 110.14(C).

Why does the calculator give a bigger cable than the 75 C ampacity table at 48 V?

Because of the terminal rating, not the conductor. NEC 110.14(C) limits a circuit of 100 A or less to the 60 C column unless every termination is listed for 75 C, and most charge controller and inverter terminals are not marked. So a 60 A controller-to-battery run needs 4 AWG (70 A at 60 C) rather than the 6 AWG (65 A at 75 C) a bare table lookup would give. Above 100 A the 75 C column applies, which is why the inverter run does not carry the same penalty.

Does a 48 V array still need heavy cable on the panel side?

Lighter than the battery side, but the array run is the long one and it is usually the voltage drop that decides it rather than the current. A 30 A array run over 40 ft at a 3% limit needs 6 AWG at 48 V, against 3 AWG at 24 V and 1 AWG at 12 V for the same run. Note that a 48 V battery bank does not mean a 48 V array: an MPPT controller commonly runs its strings at 150 V or more, and at that voltage the same power is a fraction of the current again. Size the array run on its actual string current and length.

Cable size at other system voltages

12 V wire size 24 V wire size Any voltage

Related Calculators

Continue with these related solar tools

Solar Cable Size Calculator

Smallest DC cable that carries the current and stays inside your voltage-drop limit (AWG/mm2)

DC Voltage Drop Calculator

Voltage drop on 12V, 24V and 48V DC runs by cable length, current and conductor size

Inverter Sizing Calculator

Continuous and surge inverter rating from your load, plus the DC input current the battery cable has to carry

PV Fuse and Breaker Sizing Calculator

Next standard fuse or breaker size for a PV string, controller or inverter circuit

Solar Sizing Calculator

Free solar and off-grid sizing calculators

More Calculators

© 2026 Solar Sizing Calculator. All rights reserved. A Nomogram Works site.

Privacy Policy Terms of Service Cookie Policy