Load-Shedding Survival Guide for Sandton: How to Size Your Inverter and Battery

Why sizing matters more than brand

Almost every load-shedding backup problem we are called to fix started with the wrong size, not the wrong brand. An oversized inverter on a small battery discharges the battery in an hour. An undersized inverter trips out the moment a kettle boils. A cheap battery that cannot deliver its rated peak current sags under load. The right answer starts with an honest look at what you actually need to run, and for how long.

This guide walks through the math in the way we would sit down and do it with you at a site visit, and it covers the specific loads that Sandton households care about: pool pumps, security systems, aircon and the electric geyser question.

How Eskom stages actually translate to outage hours

Load shedding stages describe how much power Eskom needs to shed from the national grid, and City Power translates that into a block schedule for each area. The practical translation for a Sandton household looks like this:

• Stage 1: one 2-hour block off per day, sometimes skipped altogether in a given area.
• Stage 2: one 2-hour block off, or occasionally two blocks totalling 2 hours.
• Stage 3: two 2-hour blocks off per day, sometimes overlapping into 4 hours.
• Stage 4: roughly 4 hours off across 24 hours, split into blocks of 2 or 4 hours.
• Stage 5: 6 to 8 hours off per day, typically in 4-hour blocks.
• Stage 6: 8 to 12 hours off per day, often as two 4-hour blocks.
• Stage 7 and 8: 12 hours or more off per day, blocks may overlap.

The key planning number for battery sizing is the longest continuous block you need to bridge. In practice, that has been a 4-hour block for most of the last few years, but stage 6 introduces the possibility of two 4-hour blocks with only 4 hours of grid between them, which does not leave much time to recharge if your only source is the grid.

What runs on what wattage

Before you can size anything, you need to know what each appliance actually draws. Nameplate ratings are the maximum. Real-world running loads are usually lower, but they add up quickly when everything runs at once.

Appliance	Typical running wattage	Notes
Fridge (family)	100 W	Compressor cycles, so average is well below peak.
Kettle	2,000 W	Full draw for 2 to 3 minutes per boil.
Wall aircon (split unit)	1,500 W	Inverter units run lower once at temperature.
Electric geyser	3,000 W	Runs for 30 to 90 minutes per heating cycle.
Wi-Fi router + ONT	20 W	Small but critical for work from home.
LED downlight	10 W each	A full house of 30 LEDs is only 300 W.
TV (55 inch LED)	100 W	Higher for OLED, similar for standard LED.
Laptop + monitor	60 to 120 W	Depends on screen size and GPU load.
Microwave	1,200 W	Runs in short bursts.
Pool pump	750 W	Runs 6 to 10 hours per day in summer.
Gate motor (idle + operate)	10 W / 200 W	Idle draw is small, operation is brief.
Alarm panel and beams	20 W	Always on.

The wattage table above is the starting point. What matters for inverter sizing is the peak simultaneous draw, and for battery sizing it is the total energy consumed over the outage duration in kWh.

Sizing methodology: essentials vs whole-home

There are two sensible ways to design a Sandton backup system, and the right one depends on what you want to run and what you are willing to spend.

Essentials only

A 2kW inverter paired with a 3 to 5kWh LiFePO4 battery bank. This covers a fridge, Wi-Fi and ONT, security system, lighting, TV and a laptop or two. Peak draw sits around 800 to 1,200 W during normal use, well within the inverter's continuous rating, and the battery lasts 6 to 8 hours on that load profile.

Sandton installed cost is around R35,000 to R55,000. Suited to smaller homes and clusters where the goal is to keep the essentials running through a 4-hour block without touching aircon or the geyser.

Whole-home hybrid

A 5 to 8kW inverter paired with a 10 to 15kWh LiFePO4 battery bank, wired to the main DB board via a changeover so most household circuits stay live during an outage. Peak draw can handle a kettle boil, microwave use and a couple of aircons on simultaneously, and the battery bridges the standard 4-hour block with room to spare.

Sandton installed cost is R80,000 to R135,000 without solar, and R110,000 to R185,000 as part of a hybrid solar system with panels. Suited to family homes and any property with a home office where any interruption is disruptive.

Real Sandton stage 6 scenarios

Numbers make the choice concrete. Two common Sandton households, both facing a stage 6 day with a 4-hour evening block from 18:00 to 22:00.

Family of four, three-bed home, essentials-only backup

Loads during the block: fridge (average 100 W), 6 LEDs (60 W), TV (100 W), Wi-Fi (20 W), alarm (20 W), two laptops (120 W). Total average running load is around 420 W. Energy consumed over 4 hours is 1.68 kWh, comfortably within a 3kWh usable battery bank. The 2kW inverter handles the brief microwave bursts. Kettle boils are moved to a stovetop gas kettle or held for grid time.

Family of five, four-bed home, whole-home hybrid

Loads during the block: fridge and drinks fridge (150 W), 20 LEDs (200 W), two TVs (200 W), Wi-Fi (20 W), alarm (20 W), two laptops (120 W), one inverter aircon on economy (600 W), kettle for 3 minutes twice (peak 2,000 W), microwave for 4 minutes (peak 1,200 W). Average running load is around 1,300 W with peaks to 3,500 W. Energy over 4 hours is around 5.2 kWh. A 5kW inverter with a 10kWh usable battery handles this with headroom for a second block on the same day.

Battery chemistry: LiFePO4 vs lead-acid

Battery choice is the second-largest cost decision after inverter size. In 2026, LiFePO4 is the default for Sandton residential installations and lead-acid is only used for very small budget systems that we generally do not recommend.

Metric	LiFePO4	Lead-acid
Depth of discharge	80 to 90 percent usable	50 percent usable
Cycle life	6,000 to 10,000 cycles	500 to 1,200 cycles
Typical warranty	10 years	2 years
Cost per usable kWh	Higher up front, lower lifetime	Lower up front, higher lifetime
Fire risk	Very low (LiFePO4 chemistry is stable)	Low but off-gasses hydrogen
Weight and space	Compact wall-mount modules	Bulky, requires ventilated cabinet

Over any reasonable service life, LiFePO4 costs less per kWh delivered. It also handles daily deep cycling, which is exactly what a hybrid solar or load-shedding backup does. Lead-acid banks that get deep-cycled daily are usually finished inside 18 months, and by then the owner has spent as much as they would have spent on lithium in the first place.

What NOT to run on backup

The single most common reason a backup system underperforms is that the wrong loads got wired into it. These appliances should stay on the grid or on a scheduled circuit, not on the backup bus.

• Electric geyser: 3,000 W continuous. A 4-hour heating cycle would drain a 12kWh battery on its own. Move geysers to solar-timed heating during the day, or switch to a heat pump or gas.
• Electric oven and hob: 4,000 to 8,000 W. Switch to gas for cooking during outages, or hold cooking for grid time.
• Tumble dryer: 2,500 W and long run times. Run during grid hours or on scheduled solar time only.
• Underfloor heating: Multiple kW per zone. Not viable on battery.
• Pool heater: Resistive heating is a battery killer. Solar pool heating or a heat pump paired with solar is the only sensible option.

How solar changes the picture

A pure inverter and battery system needs the grid to recharge. During stage 6 with 8 hours of grid time and 12 hours of load shedding, that recharge window is tight. Adding solar panels solves the problem two ways.

First, panels charge the battery directly during the day, independent of the grid. A 6kW panel array on a clear Johannesburg summer day generates 30 to 40 kWh over the course of the day, more than enough to recharge a 10kWh battery twice and still run daytime loads.

Second, when an outage falls during daylight hours, the panels supply the household load directly and the battery only cycles for early morning and evening. That extends effective backup duration and reduces battery cycles, which extends battery life.

This is why we design almost every 2026 Sandton backup as a hybrid solar system rather than as a standalone battery. The incremental cost of panels is small compared to the recurring cost of running the battery hard through winter cloudy stretches.

Brand notes: Deye, Sunsynk, Victron, Pylontech, Hubble, Freedom Won

Sandton installations in 2026 are dominated by a handful of brands that have earned their reputation. Here is how we think about each.

Inverters

• Sunsynk: The workhorse of the local hybrid market. Well-documented, widely stocked, good monitoring app, strong installer support. Our default for 5kW and 8kW residential hybrids.
• Deye: The same platform as Sunsynk in most models, sometimes at a slightly different price point. Interchangeable in practice for most installations.
• Victron: Premium option, modular, deeply configurable, excellent for complex three-phase or multi-inverter setups. Higher price point, but a favourite for owners who want granular control.

Batteries

• Pylontech: Very widely deployed, reliable, straightforward stackable modules, good warranty support locally. Our default LiFePO4 for most residential installs.
• Hubble: South African brand, longer warranty on some models, good local support and stocking. A strong alternative to Pylontech.
• Freedom Won: Premium local brand with larger capacity modules, favoured for whole-home hybrids where a single 10 to 20 kWh unit replaces a stacked bank.

Next steps

Sizing a backup system is not something to do from a brochure. We come out, measure your peak load with a clamp meter across a normal day, look at your DB board and quote a system sized to your specific needs. Every installation we complete is SANS 10142 compliant, carries an electrical certificate of compliance and, where a grid-tie is involved, is registered with City Power SSEG.

Call 010 555 0123 or explore our solar and backup packages.