Caravan & 4WD Solar Sizing Guide

Choosing the right solar setup for your caravan, camper trailer, or 4WD doesn’t need to be complicated.
This guide will help you size your solar panels, batteries, chargers, and inverter correctly based on how you actually travel and camp.

Whether you’re a weekend camper or living off-grid full-time, this page will give you a clear starting point.

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Step 1: Understand How You Use Power

Before choosing solar gear, ask yourself:

• Do you camp off-grid or mostly stay in powered sites?

• How many days between driving?

• Do you use 12V only, or also 240V appliances?

• Will you run high-draw items like:

  • Fridge/freezer

  • Coffee machine

  • Air fryer

  • Induction cooktop

  • TV or Starlink

Your usage profile determines everything else.

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Step 2: Estimate Your Daily Power Consumption

Here’s a real-world example of common caravan & 4WD loads:

👉 Typical daily usage:

• Light users: 60–80Ah/day

• Moderate users: 100–150Ah/day

• Heavy users: 180–250Ah/day

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Step 3: Battery Sizing (How Much Storage You Need)

Your battery must store enough energy to get you through the night and cloudy days.

Lithium vs AGM (Quick Guide)

• Lithium (LiFePO4):

  • Usable capacity ~90–100%

  • Lightweight

  • Faster charging

  • Best for most caravans & 4WDs

• AGM:

  • Usable capacity ~50%

  • Heavier

  • Slower charging

Battery Size Recommendations

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Step 4: Solar Panel Sizing (Real-World Output)

Solar panel ratings are tested under STC conditions, which don’t reflect real camping conditions in Australia.

Real-World Rule of Thumb

In most parts of Australia:

• Expect 70–80% of panel rating in good sun

• Less in winter or shaded sites

Solar Panel Sizing Guide

👉 Roof space, shading, and travel habits matter just as much as wattage.

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Step 5: Fixed Panels vs Solar Blankets

Fixed Roof Panels

✅ Always working
✅ No setup
❌ Limited by roof size & shading

Solar Blankets

✅ Portable & angle-adjustable
✅ Excellent winter performance
❌ Must be deployed manually

💡 Best setup:
Fixed roof panels plus a portable solar blanket for flexibility.

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Step 6: Charging While Driving (DC-DC Chargers)

If you drive regularly, a DC-DC charger with solar input is highly recommended.

Benefits:

• Charges batteries while driving

• Regulates alternator voltage

• Works alongside solar panels

• Essential for modern vehicles

Typical sizes:

• 20A → small systems

• 40A → most caravans

• 50A+ → large lithium systems

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Step 7: Inverter Sizing (240V Power)

If you plan to run 240V appliances, inverter size matters.

⚠️ Larger inverters require:

• Bigger batteries

• Thicker cabling

• Proper fusing

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Example Solar System Setups

🚐 Touring Caravan (Most Popular)

• 400–600W Fixed Solar

• 200Ah Lithium Battery

• 40A DC-DC Charger with MPPT

• 2000W Pure Sine Inverter

🚙 4WD Weekend Setup

• 200–300W Solar Blanket

• 100Ah Lithium Battery

• 25A DC-DC Charger

• 1000W Inverter

🏕️ Full-Time Off-Grid

• 800W Total Solar (roof + portable)

• 300–400Ah Lithium

• Dual DC-DC / MPPT Charging

• 3000W Inverter

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Not Sure What You Need?

Every setup is different.

If you’re unsure:

• How much solar you need

• What fits on your roof

• Whether lithium or AGM is better

• Which charger or inverter suits your system

👉 Contact our team and we’ll help you size a system that actually works for your travel style.

📞 Phone: (02) 5761 0297
📧 Email: support@starpoweradvancesolartechnology.com