Loads
How do I keep fridges and freezers running during load shedding with solar?
Put fridge and freezer circuits on the essentials / backup board, size usable battery kWh for compressor cycling (not just nameplate watts × hours), and verify the hybrid’s surge headroom when compressors start together. A typical modern fridge averages 100–200 W but spike far higher at start. Daytime PV should refill the pack between slots; grey days need reserve policy. Keep resistive geyser and stove off the same lean board.
Updated 27 October 2026 · Illustrative ranges — not a formal quote or legal advice.
Why food loads belong on essentials
Lost frozen stock costs more than many families spend on an extra 2–3 kWh of usable battery. Lights and Wi-Fi matter; protein spoilage matters more. Default Solar News 24 Stage boards include fridge/freezer, ONT/Wi-Fi, selected lights and critical plugs — not pool, borehole, oven or aircon unless explicitly sized — essentials · load shedding hub.
Average watts vs start surge
Use a plug-in meter for a week if you can. A freezer that averages 80 W may still kick 600–1 000 W at compressor start. Two cold appliances starting near-simultaneously with a microwave is a classic trip. Inverter continuous and surge ratings must clear that coincidence. Soft-start habits (avoid opening doors during the first minute of a slot) help at the margin — inverter sizing · runtime tool.
kWh maths that survives a double slot
Example: fridge + freezer average 250 W combined → 1 kWh for four hours, 1.5 kWh for six. Add ICT/lights at 150–300 W and you need roughly 2–3 kWh raw for a four-hour slot before margin. Budget ~4–5 kWh usable for grey-day doubles. A “5 kWh” sticker pack at 90% DoD with 15% reserve is tighter than marketing implies — write usable kWh — DoD · Stage 6 battery.
Tariff still leads between Stages
Keeping food cold is resilience; paying less for the kWh that refill the pack is savings. Prefer PV refill; use grid-charge-before-shed when the schedule is known and medical/food risk is high. Evening peak top-ups on TOU/Homeflex can be expensive insurance — know the c/kWh you are paying for peace of mind — grid-charge · metro tariffs · monthly savings.
Chest freezers, garages and heat
Garage freezers in Highveld summers work harder; insulation and shade cut both bill and Stage drain. Avoid siting a freezer behind a door that traps inverter exhaust heat. Chest freezers often ride through short slots better than frequent-open uprights — still measure, do not assume.
Commissioning tests
- Island the essentials board with both cold appliances running; watch for inverter faults at compressor start.
- Log SoC drop across a real or simulated 2–4 hour slot.
- Confirm geyser/stove/pool contactors are not on the same board.
- Portal login + alert thresholds set for low SoC.
Paper: read a quote · CoC.
Owner checklist
- Fridge and freezer explicitly on essentials in the single-line.
- Measured average watts + noted surge behaviour.
- Usable kWh sized for your longest realistic double slot + margin.
- PV refill / grid-charge policy written for grey weeks.
- No silent extra loads sharing the board.
Medical cold chain and chest-freezer priority
Insulin, certain medicines and expressed milk raise the stakes. Tell the designer; they may prioritise a dedicated fridge circuit, higher SoC reserve and SMS low-SoC alerts. A small bar fridge on essentials plus a large garage freezer on a separate contactor can let you shed the freezer in extreme multi-day events while protecting medicine — only with a written SOP.
Chest freezers packed full ride longer than half-empty uprights that lose cold every door open. During Stages, open once, plan meals, close. Frozen water bottles add thermal mass. None of that replaces usable kWh maths; it stretches what you bought.
AC-coupled add-ons and existing string plants
Homes with older string inverters often add AC-coupled batteries for essentials. Fridge circuits must move cleanly to the backup output; neutrals and earthing need a registered person. A plug-in UPS brick on a fridge is a weak substitute for a hybrid essentials board when slots stack — AC vs DC coupled · add a battery · UPS vs hybrid.
Bill angle while protecting food
Every kWh the pack uses overnight from prior PV is a kWh you did not import at retail. Keeping freezers efficient (door seals, dusted coils, sensible thermostat) cuts both the monthly bill and Stage drain. At 400 c, trimming 30 kWh/month of cold-appliance waste is ~R120 — small beside a geyser, real beside thin export chasing.
Further: battery cycles · warranty claims · batteries hub.
Worked family board (illustrative)
Fridge 120 W average, freezer 100 W, ONT/Wi-Fi/router 40 W, LED lights 60 W, laptop/phone charging 80 W → ~400 W continuous. Four-hour slot ≈ 1.6 kWh raw. Budget ~3 kWh usable with compressor surge margin and a second slot the same evening. Add a modem-powered alarm or medical fridge and raise the floor. Keep the 3 kW geyser element and pool pump on the other side of the contactor — forever — unless a later redesign says otherwise.
Portal alerts at 40% and 25% SoC stop silent drain from a forgotten garage chest freezer light or a teenager’s heater on a “essentials” plug. Label sockets. Commissioning without labels fails the family test.
Tariff coda: PV that refills 4 kWh after a morning slot at avoided 400 c is ~R16 of structural value plus food safety. Grid-charging the same 4 kWh at peak TOU rates can cost multiples — know which button you pressed — Cape TOU · grid-charge.
Holiday homes and remote alerts
Empty holiday homes still need cold-chain if you leave freezers on. Remote SoC alerts, a higher reserve while away, and a neighbour SOP for extended multi-day Stages matter more than another unmonitored wall pack. Switch non-essential plugs off before you lock the door — holiday home solar.
When you return to a warm freezer, document the SoC history before calling warranty; many “battery failures” are settings or unchecked loads. Keep invoices and CoC with the essentials single-line diagram.
Print the owner checklist, paste your real tariff cents beside it, and refuse any quote that cannot show the same arithmetic with your bill as the input. Solar News 24 pages are education — confirm every figure on the live municipal or Eskom PDF and on the installer datasheet before you pay a deposit. When in doubt, prioritise daytime self-use against retail rates, then Stage essentials hours, then export credits.
- Tariff name and date on the brief.
- Flexible loads listed with sun-hour plans.
- Essentials board drawn with watts.
- Usable battery kWh and hybrid backup kW stated.
- SSEG / CoC / meter responsibilities named.
- Portal access and a loaded test before final payment.
Essentials board hygiene
Fridges and freezers belong on essentials with measured watts, not guesses. A chest freezer that draws 150 W average can still need a hard start surge — confirm the hybrid’s peak covers stacked fridge + freezer + router + lights. Leave the oven and geyser off that board unless engineered — essentials · Stage 6 · geyser on backup.
Food-loss maths
One thawed freezer after a six-hour Stage can cost more than a year of the kWh that a slightly larger pack would have covered. Size usable kWh to the worst Stage pattern you actually get, not the marketing “lights only” kit.
Fridge and freezer stay on the essential board
Cold chain is the first essential load after lights and communications. Measure running and start watts, put both appliances on backup, and size usable battery kWh for the longest Stage window you design against. A fridge that shares a thin inverter with a kettle loses every time.
Test a full outage simulation before handover. Warm freezers after the first real Stage 4 mean the design failed in commissioning, not in theory.
Put this topic’s operating rule on the plant-room card in one sentence. The next Stage 4 night is the wrong time to rediscover tribal knowledge.
Quick questions
Should I buy a second fridge for Stage days?
Usually no — fix the backup board and usable kWh first. A second unbacked fridge makes the problem worse.
Will a small UPS protect a fridge?
Short UPS bricks rarely carry compressor surge for hours. Hybrid essentials boards are the residential pattern for multi-hour slots.