Table of Contents
24V Systems Overview
A 24-volt DC system is popular in solar power installations, commercial trucks, heavy-duty trolling motors, industrial control systems, and telecommunications equipment. Compared to 12V, a 24V system halves the current for the same power, which allows smaller wire gauges and reduces voltage drop over long runs.
Wire sizing in 24V systems follows the same principles as any DC circuit. The key advantage is that the higher voltage provides more headroom for voltage drop. A 3% drop on 24V is 0.72 volts, compared to only 0.36 volts on a 12V system, making 24V systems more tolerant of longer cable runs and higher loads.
Voltage Drop Formula
After computing the required circular mil area, select the next larger standard AWG wire. The constant 10.37 applies to copper conductors. For aluminum, use 17.02 instead.
Wire Size Chart
| Current (A) | 10 ft | 20 ft | 30 ft | 50 ft |
|---|---|---|---|---|
| 10 | 16 AWG | 14 AWG | 12 AWG | 10 AWG |
| 20 | 14 AWG | 12 AWG | 10 AWG | 8 AWG |
| 30 | 12 AWG | 10 AWG | 8 AWG | 6 AWG |
| 50 | 10 AWG | 8 AWG | 6 AWG | 4 AWG |
| 100 | 6 AWG | 4 AWG | 2 AWG | 1/0 AWG |
Frequently Asked Questions
Is 24V better than 12V for solar?
For systems over 400 watts, 24V is generally preferred because it halves the current, reducing wire costs and voltage drop losses. For small systems under 400W, 12V is simpler and compatible with more off-the-shelf accessories and appliances designed for automotive use.
Can I mix 12V and 24V devices?
You can use a DC-DC converter to step 24V down to 12V for devices that require it. Many solar installations include a 24V battery bank with a converter for running 12V loads like lights, USB chargers, and small electronics efficiently.
What about voltage drop in battery cables?
Battery cables should have minimal voltage drop under 1% because they carry the highest current in the system. Use the shortest possible runs and the largest practical wire gauge for battery interconnects to minimize energy waste and heat generation.