Taking a tiny home off-grid in South Africa: power, water and sewerage

Off-grid is not one decision. It is three — power, water and waste — and they are independent. Plenty of South African sites are off-grid for electricity and on municipal water, or on borehole water with a grid connection. Working out which of the three you actually need is the first job, and it changes what the unit has to be.

The whole range can be paired with solar power, gas geysers and rainwater tanks, sized and quoted for your model and site. What follows is what to think about before you ask for that quote.

Power

Solar sizing is driven by what you run, not by the size of the building. The pattern that catches people out is that the small, boring loads — a fridge running all day, a geyser element, a kettle — dominate, while lights barely register.

• Water heating is the biggest single load. An electric geyser element will size your entire system on its own. Moving hot water to gas, or to a heat pump, changes the economics of everything downstream.
• The fridge sets the overnight battery. It is the load that never stops, so it determines how much storage you need to get to morning.
• Heating and cooling are seasonal spikes. Air conditioning in a Limpopo February is a different system from the one that covers a mild spring.
• Winter is the design case. Size on the worst month, not the average, or the system that works in November fails in June.

Insulation is the cheapest energy decision you will make, because a unit that holds its temperature needs less of everything else. The expandable homes come with 75 mm EPS insulated walls and offer a polyurethane upgrade; the nature cabins use polyurethane-insulated walls; the glamping capsules use multi-layer thermal insulation, with a 100 mm polyurethane upgrade on the Space range. Double glazing is standard across the fitted ranges.

Water

Three sources, usually in combination: municipal, borehole and rainwater. Rainwater is the one people over-estimate — a roof the size of a tiny home's collects far less than intuition suggests, and South African rainfall is seasonal almost everywhere, so tank capacity has to carry the dry months, not the average.

• Work out the dry-season gap, not the annual total. That gap sizes the tank.
• Borehole water needs testing and usually treatment before anyone drinks it, and the pump is an electrical load your solar system has to carry.
• Pressure matters for how the unit feels to live in. A gravity-fed tank behaves very differently from a pumped supply at a shower head.

Sewerage

The least glamorous decision and the one most likely to be regulated. Where there is no municipal connection the options run from conservancy tanks (sealed, pumped out periodically) through septic-and-soakaway to package treatment plants — and which are permitted depends on your soil, your water table, the site's proximity to watercourses and your local authority's rules.

Get this specified early. It is a civil works job on your site rather than something the unit arrives with, and it has a way of costing more than people budget.

What arrives ready, and what does not

• X-Fold: electrics only — two plug points, a light fitting and a small DB board. No plumbing. The blankest canvas here, and the cheapest to adapt.
• Expandable homes: bathroom with factory-installed plumbing and electrical from the 18 m² up.
• Apple Cabins: integrated lighting and plumbing, bathroom fittings in all three sizes.
• Glamping capsules: complete plumbing and electrics, bathroom and geyser standard on every model.
• Nature cabins: the most complete — bathroom, kitchen, air conditioning and a storage water heater fitted as standard.

In every case the unit arrives ready to be connected to something. Solar, gas geysers and rainwater tanks are sized and quoted for your site rather than sold as a standard package, because a Karoo farm and a coastal plot are not the same problem.

A sensible order

1. 1Decide which of power, water and waste are genuinely off-grid on your site.
2. 2List your real electrical loads, honestly, including the fridge and any water heating.
3. 3Settle water heating first — it moves the solar sizing more than anything else.
4. 4Ask the municipality what sewerage solutions are permitted where you are.
5. 5Then choose the unit, and put the off-grid specification on the order.