Solar for RVs, Campervans & Boats

Why Mobile Solar Is Different

A rooftop solar system on a house has virtually unlimited space and no weight concerns. A mobile system — on a campervan, caravan, RV, or boat — operates under severe constraints:

• Limited roof area: A Tempo Traveller roof is approximately 3.5 m × 1.8 m = 6.3 m². A 540 W panel measures 2.3 m × 1.1 m = 2.5 m². You fit two panels at most — ~1,080 Wp. Most campervans have even less space.
• Weight budget: Every kilogram on the roof raises the centre of gravity and affects handling. Solar panels weigh 25–30 kg each. A 200 Ah LFP battery weighs 25–30 kg. The total system weight (panels + battery + inverter + wiring) should stay under 100–120 kg for a campervan.
• Vibration and shock: Road vibration and potholes (Indian roads are unforgiving) stress mounting brackets, connectors, and battery terminals. Every joint must be mechanically secured — not just electrically connected. MC4 connectors must be cable-tied to prevent pull-out. Battery terminals need Nyloc nuts, not regular nuts.
• Variable orientation: The vehicle parks at different angles. The panels face whatever direction the vehicle is pointing. Optimal tilt is impossible. You harvest whatever angle the roof gives you.

Panel Selection for Mobile Applications

Panel Type	Typical Watt/m²	Weight/m²	Flexibility	Mobile Suitability
Standard glass-glass (rigid)	200–220 W/m²	11–13 kg/m²	None	Caravan/RV only (flat roof, strong structure)
Glass-backsheet (rigid)	200–220 W/m²	9–11 kg/m²	None	Caravan/RV (lighter, but still rigid)
Semi-flexible (ETFE laminate)	170–190 W/m²	3–4 kg/m²	Bends to 30° curves	Campervans, curved roofs, boats
Flexible thin-film (CIGS)	120–150 W/m²	2–3 kg/m²	Highly flexible	Boats, tents, curved surfaces
Portable folding	160–180 W/m²	5–7 kg/panel	Folds flat for storage	Supplementary — deploy at camp, stow while driving

For Indian campervans (Force Traveller, Tempo Traveller conversions), semi-flexible panels are the best balance: they conform to the slight roof curves, weigh one-third of rigid panels, and can be adhesive-bonded (VHB tape + silicone) without drilling holes in the roof. The efficiency penalty (10–15% lower than rigid) is acceptable given the weight savings.

Partial Shading on Vehicle Roofs

Vehicle-mounted panels face unique shading: rooftop AC units, roof rails, luggage racks, satellite dishes, and the vehicle's own exhaust stack can cast shadows at different times of day depending on sun angle and vehicle orientation. A string of 3 panels with one partially shaded panel loses 30–50% of total output. Per-panel MPPT is critical for mobile installations.

Battery Systems for Mobile Use

Weight and volume are the deciding factors for mobile batteries. Lead-acid is essentially disqualified:

Battery Type	Energy Density (Wh/kg)	Weight for 2 kWh	Volume for 2 kWh	Cycle Life (80% DoD)
Lead-acid (tubular)	30–35	57–67 kg	~40 litres	800–1,200
AGM	35–40	50–57 kg	~35 litres	500–800
LFP (LiFePO₄)	90–120	17–22 kg	~12 litres	3,000–5,000

For 2 kWh of usable capacity, LFP weighs 17–22 kg vs 50–67 kg for lead-acid. In a campervan where every kilogram matters, LFP is the only rational choice. LFP also tolerates partial state-of-charge better than lead-acid — important because mobile solar rarely fully charges the battery (driving under tree cover, parking in shade, cloudy camping days).

Battery Mounting in Vehicles

The battery must be secured against road forces. A 25 kg LFP battery experiencing a 3G braking event generates 75 kg of forward force. Mount batteries in a steel or aluminium cradle, bolted to the vehicle chassis. Use steel straps with rubber isolation to prevent vibration damage. Place batteries in a ventilated compartment — although LFP doesn't gas during normal operation, a BMS failure could theoretically vent electrolyte. Never mount batteries above head height or in the passenger compartment without a sealed enclosure.

Sizing for Common Mobile Scenarios

Weekend Campervan (2 people, basic loads)

Load	Watts	Hours/day	Wh/day
LED interior lights	20	5	100
12V fridge (compressor)	45 (avg)	24	1,080
Phone/laptop charging	60	3	180
Water pump (12V)	50	0.5	25
USB fan	10	8	80
Total			~1,465 Wh

System: 400–600 Wp solar (2 semi-flexible panels), 2 kWh LFP battery, 1 kW inverter for occasional AC loads (laptop charger, hair dryer). Total weight: ~45 kg. Provides 1+ day autonomy without sun.

Full-Time Vanlife (AC, cooking, work-from-van)

Daily consumption: 3,000–5,000 Wh. Requires 800–1,200 Wp solar, 5–8 kWh LFP battery, 2–3 kW inverter. Total weight: 80–120 kg. Supplementary charging from alternator while driving (DC-DC charger, 20–40 A) is essential for cloudy days. Induction cooking is possible but requires a 2 kW+ inverter and draws heavily from batteries — a single 30-minute cook session uses ~1 kWh.

Marine Solar: Boats and Houseboats

Boats add salt spray, corrosion, constant motion, and the need for marine-grade everything. Key differences from vehicle solar:

• Corrosion: All electrical connections must be tinned marine-grade copper. Standard copper corrodes rapidly in salt air. Use adhesive-lined heat-shrink on all crimps. Apply dielectric grease to MC4 connectors.
• Panel mounting: Flexible panels bonded to the deck or cabin top with marine adhesive (Sikaflex 291). No penetrating fasteners — every hole in a boat is a potential leak.
• Battery chemistry: LFP is ideal for marine use — no gassing (important in enclosed boat cabins), no acid spillage risk, and lighter weight than lead-acid (weight distribution matters for sailing vessels).
• Grounding: Marine DC systems are typically floating (ungrounded) negative. Some MPPT controllers require a grounded negative. Verify compatibility before purchase.

Charge Controller Selection for Mobile Systems

Mobile systems face more variable conditions than fixed installations: constantly changing panel orientation, intermittent heavy shading, and wide temperature swings. The charge controller must handle:

• Fast MPPT tracking: Panel output changes rapidly as the vehicle moves through dappled shade (tree-lined roads). The MPPT algorithm must re-track within seconds, not minutes.
• Wide input voltage range: 2 panels in series at open circuit voltage (Voc) can reach 80–90 V on a cold morning. The controller must handle this without damage.
• Temperature compensation: Vehicle roofs get extremely hot. Panel temperature can reach 75–80°C on a parked vehicle in Indian summer. The controller must de-rate charging current based on measured battery temperature, not ambient.