Running a sauna and ice bath on inverter, solar and generator

Why the grid is not the design basis

Average available generation on the national grid was about 5,151 MW in December 2025 against an installed 13,625 MW (Nigeria National Grid factsheet), while national demand is estimated near 18,345 MW. No sensible household load plan assumes the grid will be there, which is why nearly every home we quote for has an inverter, batteries and a generator.

For us that is the starting point, not a problem. A heater and a chiller are two more loads to place intelligently in a system that already exists.

What we actually do

We start from your figures — inverter rating, battery capacity and chemistry, array size, generator rating and the house's existing base load — and place each appliance: the heater on a scheduled circuit, ideally within the solar hours; the chiller held off during heat-up and running afterwards; both locked out of starting together.

We confirm physically which circuits the changeover feeds, and we hand your electrician a drawing and a load schedule to install from. The electrical work itself is theirs; the design of the wellness loads is ours.

Honest running costs

Two numbers matter: what a sauna session costs and what the chiller costs each month. On a Band A supply the NERC tariff was about ₦209.50 per kWh in late 2025; on a diesel generator, at the NBS average of about ₦1,410 per litre in November 2025 and roughly 0.3 litres per kWh, the fuel alone costs about twice that. Solar hours are the cheapest of all, which is why the heater is scheduled into them.

Where your system cannot carry what you want, we say so and offer an alternative: a smaller cabin, a scheduled heater, an infrared cabin, or an upgrade quoted by your own installer.

Solar hours, battery nights

The pattern that works in most Lagos and Abuja homes is simple: warm the sauna in the late afternoon while the panels still produce, let the chiller pull the plunge down in the middle of the day, and leave the batteries for lights, fans and the fridge after dark. A lidded tub loses only a degree or two overnight, so the chiller rarely needs to run on battery at all.

Where the generator is the only backup, we set the controls so that a changeover never sees the heater and chiller start together — the moment most generator trips happen.

In short

• Heater and chiller never start together — enforced in the controls
• Heater warm-up scheduled into solar hours where there is solar
• Essential-board circuits verified on site, not assumed
• Session cost and monthly chiller cost calculated for your system