YOUR ENERGY PROFILE.
This document contains the sizing of your future electrical installation, calculated based on your appliances.
Inventory:
Battery
To guarantee 0WH without damaging your bank (80% max discharge):
Solar
Minimum power required to recharge your consumption:
220V AC
Maximum power (with 25% safety margin).
12V Cable Sizing Guide
Use this professional reference table to select the correct gauge (mm²) for your cables. For 12V in a van, the maximum tolerated voltage drop is 3%. Always use multi-stranded flexible automotive wire.
| 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 |
Fuse Sizing
The fuse protects the wire, not the appliance. Always place it as close to the power source as possible (battery or busbar).
- Wire 1.5 mm² → Max fuse 10A
- Wire 2.5 mm² → Max fuse 20A
- Wire 4 mm² → Max fuse 30A
- Wire 6 mm² → Max fuse 40A
- Wire 10 mm² → Max fuse 60A
SCHÉMA ÉLECTRIQUE
PANNEAUX SOLAIRES
0W
REGULATEUR MPPT
BATTERIE AUXILIAIRE
0 Ah
Lithium LiFePO4
BOÎTE À FUSIBLES 12V
Pompe, Leds, Frigo...
CONVERTISSEUR 220V
NON REQUI
SHOPPING LIST
Where to find this equipment? Here is the community-approved selection.
12V 6-way Fuse Box
Mandatory protection
Digital Multimeter
Test your connections
Heavy Duty Crimping Tool
For perfect lugs
Heat Shrink Tubing
Insulation and safety
Comparison table
| Profile | Usage/day | LiFePO4 size | Solar needed |
|---|---|---|---|
| Weekend truck camper | 500 Wh | 125Ah → 150Ah | 150-200W |
| Standard offgrid | 900 Wh | 225Ah → 250Ah | 250-350W |
| 4-season insulated | 1,200 Wh | 300Ah | 350-450W |
| Boondocking comfort | 1,600 Wh | 400Ah | 500-600W |
About this tool
Off-Grid Truck Camper Solar and Battery Sizing Guide
Truck campers face unique challenges compared to van builds: limited roof space for solar, a smaller and taller profile, and often a need for more rugged self-sufficiency.
Roof Space Limitations by Truck Camper Type
| Camper Type | Usable Roof Area | Max Solar Potential |
|---|---|---|
| Pop-up truck camper | 1.5-2.5 m² | 200-400W |
| Hard-side slide-in (short bed) | 2.5-3 m² | 400-600W |
| Hard-side slide-in (long bed) | 3-4 m² | 600-800W |
| Flatbed truck camper | 4-6 m² | 800-1,200W |
Sizing the Solar and Battery System
For a truck camper couple living off-grid: daily consumption typically 800-1,200Wh/day (fridge + lighting + laptops + water pump + occasional inverter use). With 400W on a pop-up or short-bed: at 5h peak sun = 1,700Wh/day — sufficient for summer self-sufficiency. In winter with 2h peak sun: only 680Wh — supplement with engine charging.
Recommended configurations:
| Use Case | Solar | Battery | Engine Alt |
|---|---|---|---|
| Weekend adventures | 200-300W | 100-150Ah LiFePO4 | Not critical |
| Extended boondocking | 400-600W | 200-300Ah LiFePO4 | 30A DC-DC B2B |
| Full-time off-grid | 600-800W+ | 300-400Ah LiFePO4 | 40-60A DC-DC B2B |
Alternator Charging for Truck Campers
Trucks often have powerful commercial-grade alternators (120-220A). A DC-DC (B2B) charger of 30-60A is ideal and provides a reliable, controlled charge from the truck battery. Avoid old-school split-charge relays — they can drain the starter battery.
One hour of driving with a 40A B2B = 40 × 12 × 1 = 480Wh — equivalent to 200W of solar for 3 hours. Daily driving makes a huge difference to battery levels.
Weight Considerations
LiFePO4 saves critical weight on a truck camper where payload is a primary constraint:
- 200Ah AGM: ~60-70 kg
- 200Ah LiFePO4: ~22-28 kg
- Weight saved: 35-50 kg — significant for truck payload ratings
Expert tip: On a pop-up truck camper, flexible solar panels (CIGS or amorphous silicon) allow installation on curved surfaces that rigid panels can't reach. They produce 5-10% less per watt but give meaningfully more total surface area on curved camper tops.
Truck camper specific constraints for solar and battery sizing: the payload capacity of your truck is the primary constraint that changes everything. A full-size F-250 (1,700kg payload) can accommodate 400Ah LiFePO4 (approximately 50kg for four 100Ah units) + 600W solar on an aluminum roof rack without approaching payload limits. A compact Toyota Tacoma (700kg payload) must run a leaner system — 100-200Ah LiFePO4, 300W max solar — given that the camper body itself already uses 200-350kg of that payload budget.
Slide-in camper vs permanent truck bed conversion: slide-in campers have existing wiring harnesses (shore power inlet, 7-pin truck connector for battery trickle charge from truck while driving). These existing systems are usually 12V AGM. Upgrading to LiFePO4 requires verifying that all existing chargers (converter/charger) support LiFePO4 profile — most post-2018 units do, but verify in the manual. The Parallax 8345 converter common in North American RVs requires a charging profile update via dip switches.
Air conditioning for full-time truck campers: the Advocate one-piece 18V batteries for Zero-Breeze Mark 2 (€749) provide 2-8 hours of cooling in extreme heat. For all-night cooling: Dometic RTX 2000 12V rooftop (150W peak, 60W sustained) integrates with the truck camper roof and draws from the existing 12V house battery system — achievable with 300Ah LiFePO4 and 600W solar in the US Southwest.