The Ultimate Van Life Solar & Battery Calculator (With Layout)

🚐 Dreaming of a life on the road? Whether you’re chasing sunsets, exploring remote trails, or just living off-grid, a solar setup in your van keeps your lights on, fridge cold, and devices charged — without relying on campsites or generators.

☀️ But how much solar do you really need?

Let’s break it down with a simple DIY solar calculator you can use to plan your perfect vanlife energy system!

💡 Why You Need a Solar Calculator for Your Van

Every van build is different. Your power needs depend on:

• How often you use lights, fans, and appliances
• Whether you have a fridge, microwave, or heater
• Your laptop, phone, and entertainment habits

A solar calculator helps you:

• Right-size your solar panel setup
• Avoid running out of power on the road
• Save money by not overspending on batteries and panels

✅ Step 1: List Your Daily Energy Usage

Make a list of all the devices you plan to use in your van and their wattages.

Example list:

Device	Power (Watts)	Hours per Day	Watt-hours/day
LED Lights	20 W	5 hrs	100 Wh
12V Fridge	50 W avg	24 hrs	1200 Wh
Laptop	60 W	2 hrs	120 Wh
Phone Charging	10 W	3 hrs	30 Wh
MaxxFan Vent	30 W	6 hrs	180 Wh

Total Daily Usage = 100 + 1200 + 120 + 30 + 180 = 1630 Wh/day

To simplify this process, use the calculator below (Click + Device to start adding appliances to the list)

The next two steps show you how to calculate the solar panel and battery strength. You can skip ahead to the calculator

✅ Step 2: Calculate Required Solar Panel Size

Assume about 4-5 hours of peak sunlight per day depending on your location.

Formula:

Solar Panel Size (Watts) = Total Daily Usage (Wh) ÷ Peak Sun Hours

Example:

Solar Panel Size = 1630 ÷ 4 = 407.5 Watts

📌 In this case, you’d want at least 400–450 W of solar panels.

✅ Step 3: Calculate Battery Bank Size

Next, calculate your battery storage needs.

Formula:

Battery Bank (Ah) = (Total Daily Usage ÷ System Voltage) ÷ Depth of Discharge (DoD)

Assume:

• System Voltage = 12V
• Safe Depth of Discharge = 80% for lithium batteries (0.8)

Example:

Battery Bank = (1630 ÷ 12) ÷ 0.8 ≈ 170 Ah

✅ So you’d need about 170 amp-hours at 12V — a 200Ah lithium battery would be perfect.

Use the calculator below – enter your total daily usage calculated in Step 1 above.

📌 A practical requirement is to enter a System Loss factor that represents the inefficiencies that naturally occur in a solar power system. It’s the percentage of energy that is lost and not usable when converting sunlight into electricity.

Typical System Loss Factors are:

• 25% or more if conditions are tough (lots of shading, older equipment, extreme heat)
• 10% – 15% for very well-designed, premium systems
• 20% is commonly assumed for average real-world conditions

🛠️ Bonus Tips for Van Solar Success

• Add 20–30% margin for cloudy days
• Use a MPPT charge controller for maximum efficiency
• Secure panels with aerodynamic mounts to reduce drag
• Consider a DC-DC charger for alternator charging backup

🔁 Related Posts

• Solar Battery Bank Calculator
• What is Depth of Discharge?