Solar & Battery Electrical Calculator for Campervans | VanPowerCalc

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Winter vanlife is the ultimate test of your electrical system. When it's -15°C outside, your diesel heater runs 24/7, solar production drops 70%, and your LiFePO4 batteries refuse to charge below 0°C. This build is designed to handle all of that.

This premium setup combines 400Ah LiFePO4 with heated BMS, 600W tiltable solar panels, a 40A DC-DC charger, and a 3000W inverter. The diesel heater draws minimal electricity (10-25W) but needs a dedicated circuit with its own fuses.

Pro tip: in the mountains, tilt your solar panels. In winter, the sun is low (20-30° above horizon in December). A flat panel loses 50% production. Tilt mounts at 60° (Renogy Tilt Mount, ~€40/pair) can double your winter output. Some vanlifers add a portable 200W panel they aim manually — the most effective solution for stationary camping.

The Winter Challenge: When Cold Tests Your Limits#

Winter vanlife in the Alps, Pyrenees, or Scandinavia is magical. But it's also the most demanding environment for an electrical system.

The 4 Enemies of Winter Electricity#

Solar production drops 3-4x — In December in central Europe, a 100W panel produces ~100-150Wh/day vs 500-600Wh in July
LiFePO4 won't charge below 0°C — The lithium chemistry freezes and cells degrade if you force charging
Consumption increases — Diesel heater (10-25W electrical), more lighting, more cooking
Condensation — Moisture attacks electrical connections and can cause short circuits

The Solution: Heated BMS#

LiFePO4 batteries with built-in heated BMS (Redodo, LiTime, Power Queen) have a heating element that warms cells before accepting charge. Cost: €50-80 more than standard. This is NON-NEGOTIABLE for winter.

Winter Power Consumption#

Diesel heater: 24h x 15W = 360Wh (electrical draw only)
50L fridge: 420Wh
LED lighting (short days, 14h): 100Wh
Laptop + Starlink: 800Wh (if digital nomad)
Ventilation (moisture removal): 50Wh
Water pump: 15Wh
Coffee machine: 80Wh
12V heated blanket: 8h x 50W = 400Wh
Total: ~2,225Wh/day

Why 600W Panels, Not 400W#

In December in central Europe (2.5h PSH): 600W x 2.5h x 0.8 = 1,200Wh/day. Not enough alone, but combined with 30A DC-DC while driving 1h/day (360Wh), you reach 1,560Wh. The ~665Wh deficit draws from the 400Ah reserve (4,800Wh).

Discharging: yes, down to -20°C no problem. Charging: NO, most BMS cut off charging below 0°C to protect cells. Solution: batteries with built-in heated BMS (Redodo, LiTime) that warm cells to 5°C before accepting charge. Also add Armaflex insulation around the battery box.

Two options: Webasto Air Top 2000 (premium, ~€1,200, quiet, reliable) or Chinese diesel heater (budget, ~€150-200, noisier but effective). Both consume 0.1-0.25L/h diesel and 10-25W electrical. For -15°C, the 2kW is enough in a well-insulated van (Sprinter, Ducato). Below -25°C, go for 5kW.

Not alone. In December in central Europe, 600W produces ~1,200Wh/day — insufficient for ~2,200Wh winter consumption. You must supplement with DC-DC (1-2h driving/day = 360-720Wh) and have 400Ah reserve for storm days. That's why this is the most expensive build: winter demands redundancy.

Electrical system alone: about €3,200. Add diesel heater (€150-1,200 depending on brand), Armaflex insulation (€200-400), and winter accessories (heated blanket, engine preheater), and you're at €3,500-4,500 all-in. It's an investment, but it's the price of mountain freedom.

Current (A)	Round trip < 2m	Round trip 4m	Round trip 6m
5A (LEDs, USB)	1.5 mm²	2.5 mm²	4 mm²
10A (Fridge, Pump)	2.5 mm²	4 mm²	6 mm²
20A (Heater)	4 mm²	10 mm²	10 mm²
50A (DC/DC Booster)	10 mm²	16 mm²	25 mm²
100A (Inverter)	25 mm²	35 mm²	50 mm²

Component	Model	Specs	Price
Heated LiFePO4	Redodo 12V 400Ah	400Ah, heated BMS, -20°C	~€850
Solar Panels	Renogy 3x200W Mono	600W total, roof mount	~€420
MPPT Controller	Victron SmartSolar 150/35	35A, 150V input max	~€220
DC-DC Charger	Victron Orion-Tr Smart 12/12-30	30A, Bluetooth	~€160
Pure Sine Inverter	Victron Phoenix 12/3000	3000W continuous	~€650
Diesel Heater	Vevor / Chinese 2kW	2kW, LCD thermostat	~€180
Fuse Box	Blue Sea ST Blade 12	12 circuits	~€45
Battery Monitor	Victron SmartShunt 500A	Bluetooth, VictronConnect	~€75
Battery Cables	50mm² + ANL lugs	Heavy-duty set	~€50
Solar Cables	MC4 + 6mm²	20m, Y-connectors	~€40
Battery Insulation	Armaflex 19mm	Complete battery box	~€40
Heated Blanket	12V 150x80cm	50W, thermostat	~€45
Outlets + USB	USB-C PD + 12V x4	Complete kit	~€50
LED Lighting	Dimmable spots + strip	12-point kit	~€55
Miscellaneous	Fuses, conduit, lugs, mounts	Pro wiring kit	~€70
TOTAL			~€2,950

Winter Van Setup: Vanlife in Mountains and Scandinavia

Example calculation for your setup

Your electrical appliances

Build custom

Battery

Solar

220V AC

12V Cable Sizing Guide

Fuse Sizing

SCHÉMA ÉLECTRIQUE

PANNEAUX SOLAIRES

RÉGULATEUR MPPT

BATTERIE AUXILIAIRE

BOÎTE À FUSIBLES 12V

CONVERTISSEUR 220V

Comparison table

About this tool

The Winter Challenge: When Cold Tests Your Limits#

The 4 Enemies of Winter Electricity#

The Solution: Heated BMS#

Winter Power Consumption#

Why 600W Panels, Not 400W#

Frequently asked questions

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Appliance	Power	Usage/day	Wh/day
Compression fridge	45W	24h	1080
LED lighting	20W	4h	80
Water pump	30W	0.5h	15
Phone charging	15W	2h	30
Daily consumption			1205 Wh