A van electrical calculator helps you plan the electrical system for a camper van conversion. Unlike full-size RVs, vans have limited roof space for solar panels and rely heavily on alternator charging while driving. Enter your appliances, configure battery type and system voltage, set your alternator charging input, and get a complete power budget with battery bank and solar panel recommendations tailored for van life.
Add Appliances
Click a preset to add it, or enter a custom appliance below. Adjust watts and hours as needed.
Add Custom Appliance
System Configuration
US average: 4-5 hours
Hours of driving per day
DC-DC charger output (typical 20-40A)
Usable area after fans, vents, etc.
System Recommendation
Roof Space Warning
Power Budget Breakdown
Panel Size Options
| Panel Size | Panels Needed | Total Watts | Roof Area (sq ft) | Fits? |
|---|
Consumption Breakdown
| Appliance | Watts | Hours/Day | Wh/Day |
|---|
How to Use the Van Electrical Calculator
Planning the electrical system is one of the most important steps in any van conversion. An undersized system means running out of power on cloudy days, while an oversized one wastes money and precious cargo weight. This van electrical calculator helps you find the right balance by factoring in appliance usage, battery chemistry, alternator charging from daily driving, and your van's limited roof space.
Step 1: Add Your Appliances
Click the van-specific preset buttons to quickly add common appliances like a MaxxFan, diesel heater, 12V compressor fridge, LED lights, and phone or laptop charging. Each preset includes typical wattage and daily usage hours for van life. You can also add custom appliances by entering the name, wattage, and hours per day. The calculator shows a running total of your daily watt-hour consumption.
Step 2: Configure Your System
Choose between lithium (LiFePO4) and AGM batteries. Lithium batteries offer 80% usable capacity and are lighter, making them ideal for vans where weight matters. Set your system voltage (12V for most van builds), days of autonomy, and peak sun hours for your typical location. Then enter your daily driving hours and DC-DC charger amperage to account for alternator charging. Finally, enter your available roof space in square feet so the calculator can warn you if panels will not fit.
Step 3: Review Your Power Budget
Click Calculate Power Budget to see your complete system recommendation. The results show your daily consumption, required battery capacity in amp-hours, solar wattage needed after subtracting alternator charging, and a visual breakdown of how much power comes from driving versus solar. The panel options table shows how many 100W or 200W panels you need and whether they fit your roof.
Van-Specific Considerations
Unlike full-size RVs, vans have unique constraints. Roof space is limited, so alternator charging through a DC-DC charger is often your primary charging source. Most van lifers drive 1-3 hours daily, which at 30 amps can contribute 360-1,080 Wh per day. If your driving covers most of your power needs, you may only need a small solar array as a backup for days you stay parked. Keep the system as simple as possible: fewer components mean fewer points of failure on the road.
FAQ
Is this van electrical calculator really free?
Yes, completely free with no signup required. All calculations run locally in your browser. Use it as many times as you need to compare different configurations for your van build.
Is my data safe when using this tool?
Absolutely. Everything runs entirely in your browser using JavaScript. No appliance data, power usage, or personal information is transmitted anywhere. You can even use it offline once the page loads.
What is the difference between lithium and AGM batteries for a van?
Lithium (LiFePO4) batteries can safely discharge to 80% depth of discharge and are lighter, while AGM batteries should only discharge to 50% DOD. For van builds where weight and space matter, lithium is usually the better choice despite higher upfront cost.
How much power does alternator charging add?
A typical van alternator can charge at 20-40 amps via a DC-DC charger. At 30A and 12V, two hours of driving adds about 720Wh to your batteries. For daily driving, this can significantly reduce or even eliminate the need for solar panels.
How much roof space do I need for solar panels?
A 100W panel is roughly 5.4 square feet and a 200W panel about 10.8 square feet. Most standard-length vans have 40-60 square feet of usable roof space after accounting for fans, antennas, and roof racks. This calculator warns you if your solar needs exceed available roof space.
Should I use a 12V or 24V system in my van?
Most van conversions use 12V because it is compatible with standard automotive accessories and 12V appliances. A 24V system is more efficient for higher loads (over 3,000Wh/day) as it reduces wire gauge requirements and losses, but requires a 24V-to-12V converter for standard accessories.
How many days of autonomy should I plan for?
For van life with regular driving, 1 day of autonomy is usually sufficient since alternator charging supplements solar. If you park for extended periods without driving, 2-3 days of autonomy provides a safer buffer for cloudy weather.
Can I run an induction cooktop in a van?
Yes, but induction cooktops draw 1,500-1,800W and require a large inverter (at least 2,000W). Short cooking sessions of 15-20 minutes are manageable with a properly sized battery bank. Many van lifers use propane stoves instead to reduce electrical demand.