Choosing Between 12V and 24V Off-Grid Solar Systems - What's Best for Your Caravan or Boat?

Most caravan, RV, and boat owners with solar start with 12V systems, which are commonly used in automotive electrical systems. 12V systems are often seen as the cheapest and simplest option. This can be true when you want to run "just the basics." But sometimes, 'the basics' uses more power than people expect!

When your power requirements or size of the solar array increase, choosing a 24V solar electrical system could save money in the long run.

What is System Voltage?

The terms 12V, 24V, 48V, or 230V refer to the voltage of commonly used electrical systems. Voltage can be thought of as the "pressure" that pushes electric current through wires to power your devices. A higher voltage means more efficient power delivery because less current is needed to produce the same amount of power.

230V is found in New Zealand homes, 12V is often used in caravans or other off-grid setups, while 24V and 48V are used in higher-powered systems.

Why Does Voltage Matter?

Voltage affects how efficiently electricity travels between your solar panels, batteries, charge controller, and appliances. A higher voltage system (like 24V or 48V) uses less current to deliver the same power as a lower voltage system (like 12V). This allows for smaller wires, smaller components (like MPPT controllers), lower energy loss, and better performance for larger systems.

Why 12V is Popular (and Affordable) in Caravans and Boats

• 12V solar systems are popular because components like batteries, inverters, and charge controllers are generally cheaper due to mass production.
• Many parts are easily available because the automotive industry has long used 12V systems.
• If you’re only running basic appliances like lights, phone chargers, or a small fan, the overall system cost is hard to beat.
• Many caravan, RV, and boat appliances are designed specifically for 12V systems, allowing direct connection to batteries without an inverter, saving cost and efficiency.

When 12V Might Get Expensive

As power demands increase, 12V systems can become less efficient and more expensive:

• Higher Power = Higher Current: 12V systems require double the current to produce the same power as a 24V system. For example, running a 1200-watt device on 12V draws 100 amps, while the same device on 24V draws 50 amps. High current means thicker cables and more expensive components like solar controllers.
• Voltage Drop Over Long Wiring: Longer wires in a 12V system result in energy loss as heat. This can force you to spend more on thicker wires, which can cost over $50 per metre!
• Adding high-wattage appliances (air conditioners, kettles, hairdryers, larger fridges, microwaves) makes higher voltage systems more cost-effective.

Why 24V Systems Might Be Cheaper in the Long Run

• Less Current: 24V systems deliver the same power with less current, reducing strain on cables and equipment.
• Cheaper Wiring and Components: Thinner cables and smaller components are sufficient, lowering costs for medium-sized setups.
• Better for Add-Ons: 24V systems handle higher loads more efficiently, which is useful if you upgrade your appliances later. Some 12V appliances may need a DC-DC converter, but it’s manageable.

Quick Comparison

Voltage	Best For	Why It’s Budget-Friendly	Potential Extra Costs
12V	Small, simple setups (~1000W or less)	Affordable components, compatible with 12V appliances	Expensive wiring and inefficiency as power needs grow
24V	Medium setups (1000–3000W) with room to grow	Reduces wiring costs and energy loss for larger systems	Requires converters for 12V devices
48V	High-power off-grid setups (5000W+)	Efficient for powering many appliances	Requires a registered electrician to install

Conclusion

The choice between 12V, 24V, or 48V solar systems shows why proper solar design matters. LUX Solar's free design tool, AnyKit, calculates your power requirements and automatically designs optimized 12V or 24V systems. You can compare the costs and see which system is best for your setup.

Visit www.lux.solar/anykit to try it today!