Van Life Solar Systems

Build a reliable 12V electrical system for full-time van living. Solar panels, lithium batteries, and alternator charging — all covered.

Size My Van System

Van Solar Is Different from RV Solar

A cargo van conversion has unique constraints: limited roof space (often 60–120 sq ft of usable panel area), a curved or ribbed roof that complicates mounting, and the ability to charge from your alternator while driving — something RVs can't do as efficiently due to longer wiring runs.

A well-designed van electrical system has three charging sources: solar, alternator (via DC-DC charger), and shore power (optional). Most full-time van lifers run 200–400W of solar and rely on driving 30–60 minutes per day to top up the battery in low-sun periods.

Typical Van Life Power Loads

ApplianceWattsDuty CycleHours/DayWh/Day
12V DC compressor fridge45W35%24h~378 Wh
LED lighting (4 strips)32W100%4h128 Wh
Laptop65W100%6h390 Wh
Phone charging ×240W100%3h120 Wh
Fan (Maxxair/Fantastic)35W100%6h210 Wh
Water pump60W15%24h216 Wh
Typical daily total~1,442 Wh

Recommended Van Builds

Weekend Warrior
  • 100–200W solar
  • 100Ah LiFePO4
  • 30A DC-DC charger
  • 500W inverter

Works for light weekend use. Relies heavily on alternator charging.

Full-Time Build Sweet Spot
  • 300–400W solar
  • 200Ah LiFePO4
  • 40–50A DC-DC charger
  • 1,000–2,000W inverter

Handles all typical vanlife loads. 2+ days of autonomy.

Heavy-Duty Build
  • 600W+ solar
  • 300Ah LiFePO4
  • 60A DC-DC + high-output alt
  • 2,000W inverter

For AC, power tools, or extended off-grid periods.

Alternator Charging

While driving, your van's alternator produces 12–14.8V DC. This can charge your house battery, but you should never connect a lithium (LiFePO4) battery directly to the alternator — lithium batteries will draw full current until full, potentially overheating and damaging the alternator.

The Solution: DC-DC Charger (B2B Charger)

A DC-to-DC charger (also called a Battery-to-Battery or B2B charger) sits between the vehicle's starter battery and the house battery. It:

  • Limits current draw so the alternator isn't overloaded
  • Provides proper multi-stage charging profile for lithium
  • Isolates the house battery from the starter battery (prevents dead starts)
  • Often includes an MPPT solar input (e.g., Renogy DCC50S)
Sizing rule: A 30A DC-DC charger delivers ~400W of charge power. A 50A unit delivers ~650W. Aim for no more than 25% of your alternator's rated output to keep it healthy long-term.

High-Output Alternator Upgrades

If you're in a cloudy climate or park without sun access, a high-output alternator lets you charge your battery bank while driving — turning commute time into charging time. Here's what's available for the most common US van platforms:

Van Platform Stock Alternator Upgrade Options Est. Cost
Ford Transit
(2015+)		 210–250A Mechman 370A, Nations Alternator 300A $600–$900
Ram ProMaster
(2014+)		 220A (high-output option from factory) Mechman 280A $550–$750
Mercedes Sprinter
(2014+)		 180A Nations Alternator 270A+ $700–$1,000
Chevy Express / GMC Savana 145–165A Mechman 220–250A $400–$650
Ford E-Series 130–200A Mechman, Nations $400–$650

Note: Always pair a high-output alternator with a proper DC-DC charger. Running 220A+ into a lithium battery without current limiting will destroy the battery BMS and potentially the alternator.

Solar Panel Mounting for Vans

Cargo vans have curved, ribbed, or angled roofs that make mounting harder than a flat RV roof:

  • Rigid panels + aluminum crossbars — Most efficient, best airflow underneath, but adds height. Common for Transit High Roof and ProMaster High Roof.
  • Flexible/semi-flexible panels — Can be bonded directly to curved roofs with VHB tape or Sikaflex. Less efficient (~15% vs ~22% mono), degrade faster if heat-trapped.
  • Tilting mounts — Gutter/side-mount rails with tilt capability. Great for winter sun but adds complexity and wind noise at highway speed.
Flexible panel warning: Many cheap flexible panels on Amazon claim 200W but deliver much less in real-world conditions. Stick to reputable brands and look for real test data from the van community before buying.
Battle Born 100Ah LiFePO4

The most popular battery in the van life community. Lightweight (31 lbs), 10-year warranty, series-connectable for 24V builds.

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Renogy 100Ah LiFePO4

Best budget LiFePO4 for 12V van builds. Cannot be series-connected but excellent for parallel 12V configurations.

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Calculate your van electrical system

Use the Van preset in our calculator. It pre-loads typical vanlife appliances and shows you exactly what you need.

Open Van Calculator