Solar Systems for Tiny Houses, Caravans and Boats

The rules that apply on land do not apply here

The most common mistake in mobile systems is trying to fit conventional household thinking into a structure that moves. Here, space, weight, battery placement and resistance to vibration in transit all have to be considered at once.

Weight matters especially. A 40 kg battery that is irrelevant in a house comes straight off the axle capacity of a tiny house or caravan; on a boat it affects balance and trim. Lithium rather than lead-acid is therefore all but mandatory.

Vibration is a source of failure never encountered on land. Movement loosens terminals and fatigues cables. All connections are therefore made vibration-resistant and cables are clamped so they cannot move.

Not panel count — an energy budget

The right solution starts by establishing your total daily energy budget. How many hours will the refrigerator run, how often will the water pump cut in, how much will laptop and phone charging come to — until these are clear, neither battery nor inverter can be selected.

High loads such as air conditioning, induction hobs or water heaters multiply the cost of the system. Covering those with gas, shore power or an alternative is often more economical; once the energy budget is drawn up, it becomes clear which appliance should run on electricity and which should not.

• Refrigerator / cool box — runs continuously and is the deciding load
• Water pump and booster — brief but high current
• Lighting, phone, laptop and camera charging
• Navigation electronics (on a boat) — low draw but must not be interrupted

Every structure has its own constraint

In a tiny house the deciding factor is transportability: axle capacity and road safety determine from the outset where and how the battery and inverter are placed. Correctly sized cabling that does not heat up in a compact space is critical as well.

In a caravan the real constraint is surface area. Ventilation, air conditioning and aerial units take up a significant part of the roof. The layout is drawn around how those units cast shade through the day; a single shaded panel can reduce the output of the whole string.

On a boat, salt is the deciding factor. Salt-laden air rapidly degrades standard aluminium profiles and steel fasteners, so we use stainless (A4/316 grade) fasteners and marine-grade cable. For bimini or deck mounting, flexible panels may be preferred.

Why lithium (LiFePO4)?

In mobile systems the battery choice determines everything else:

• Weight: roughly a third of lead-acid for the same usable capacity
• Deep discharge: 80–90% of capacity can be used safely
• Life: 3,000–6,000 cycles, meaning over ten years in normal use
• Maintenance: no topping up and no ventilated compartment required