Induction Cooking

An induction hob is a transformer with the pot as its secondary winding: a 20–100 kHz alternating field in the coil induces eddy currents in a ferromagnetic pot base, and the pot itself becomes the heating element. About 85% of electrical energy ends up in the food — against ~40% for LPG and 10–15% for open-fire charcoal cooking — and the hob surface stays cooler than the pot, which matters in a shelter full of children. SolarHearth's 1.8 kW single-coil hob is driven by a resonant stage directly from the 48 V DC bus (no inverter), costs about $65 at commodity scale, and gets a pot-locking rim for the vigorous stirring that ugali demands.

A family of five cooks two hot meals on 2.0 kWh/day. The same coil moonlights: it regenerates the optional water-from-air cartridge through its steel susceptor shell, drives the flow pasteurizer pot, and — at 400–500 °C in a retort pot — chars bones into fluoride-removal media (chapter 6).

In the camps this unit is sized for — Mahama in Rwanda, Kakuma and Dadaab in Kenya — the staples are long-simmer dishes: dried beans (2–3 hours), githeri, maize porridge, ugali. Three consequences are designed in. Timing: the main meal is cooked at dusk, after the sun — which is why the battery is sized for the evening meal and a daylight-only cooker was rejected. Long simmers: beans are brought to boil on the hob, then finished in the insulated retained-heat basket — without it, bean days would run ~3 kWh instead of 2. Pots: the ubiquitous East African sufuria is aluminum, which induction cannot heat — so the unit ships with two flat-bottomed stainless-clad sufuria-pattern pots. Cooking demonstrations and a familiar pot shape have mattered more to clean-cooking adoption in these camps than any efficiency number.

The retained-heat basket (a modern haybox: an insulated cavity that lets a boiled pot finish cooking on its own stored heat) is standard equipment, not an accessory — it trims ~15% of cooking energy, frees the hob for the next pot, and needs no power at all.

Camp households typically spend $15–40 a month on charcoal or firewood. The core cooker — 466 W of PV, 1.5 kWh of battery, the hob, enclosure and controls — prices at $655, or $8.50/month amortized over 8 years: it repays itself in displaced fuel in 1.5–3.5 years before counting anything else. What the fuel line doesn't show: indoor smoke from solid-fuel cooking is a leading child-health hazard, firewood collection is a documented protection risk for women and girls, and flameless cooking removes the ignition source behind catastrophic camp fires. Clean-cooking carbon credits — an established financing channel — can underwrite a meaningful slice of the capital cost.

Tea deserves its own line. Sweet milky chai is a several-times-daily ritual across Somali, Sudanese, and Congolese communities, and tea stalls are often the most numerous camp enterprise. A few 1–2 L boils cost 0.1–0.2 kWh/day, the pasteurizer's heat exchanger already delivers ~70 °C water to a hot-water tap that halves time-to-boil, and a tea-stall tier — hob, large kettle, verified-safe badge — is the smallest business system in the lineup at roughly $800.