Updated November 2026 · SAPVIA Certified · PV GreenCard installer · CoC on every install
Load-shedding has been quieter lately, but Cape Town households still lose power to cable theft, substation faults and planned maintenance, and nobody can promise load-shedding won’t return. A battery backup system keeps your lights, Wi-Fi, fridge, TV, alarm and gate running when the grid goes down, and it switches over automatically.
Sundial Solar installs inverter and lithium battery systems across Cape Town, either on their own or as the first step towards full solar. We’re SAPVIA Certified and every install gets a CoC.
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Backup only, or backup with solar?
Backup only means an inverter and battery that charge from the grid and power your essential circuits during outages. It is the lowest cost way to stay on, but it does not reduce your electricity bill.
Backup with solar adds panels so the battery charges from the sun, which cuts your bill and keeps you running for longer during long outages. Many clients start with backup and add panels later; we size the inverter so that’s easy. See our solar cost guide for full systems.
How we size your battery
We start with what you want running, not with a product. A typical “essentials” circuit (lights, plugs for Wi-Fi and TV, fridge, alarm and gate) uses a few hundred watts most of the time. Kettles, ovens, geysers and pool pumps are usually kept off the backup circuit, because they would drain a battery quickly. As a rough guide:
- 5 kWh: essentials through a typical evening outage.
- 10 kWh: essentials overnight, or a larger home through a long outage.
- 15 – 20 kWh: larger homes, home offices and medical equipment, or systems designed to rely on the grid as little as possible.
We’ll confirm the right size after looking at your DB board and how you use power.
Adding a battery to an existing system
Already have solar panels but no battery, or a battery that no longer lasts? We can often add storage to your current inverter, provided it’s battery-compatible. If not, we’ll tell you plainly whether an inverter upgrade makes sense. Choose “Add to my existing system” in the form below.
Safety and where the battery goes
Lithium batteries are safe when installed correctly, with proper ventilation, clearances, protection and cabling. We install to the relevant wiring code and the manufacturer’s requirements, and we discuss placement (garage, outside wall in a ventilated enclosure, or utility room) during the site check. Read more in our post on battery safety.
What to put on the backup circuit
Before the installation we walk through your DB board with you and agree which circuits move to the backup side. A practical list for most Cape Town homes is: all lights, the Wi-Fi router and fibre box, TV and decoder, fridge and freezer, alarm, electric fence energiser, gate and garage motors, and a few plugs in the study for laptops. Things we usually leave on the grid side are the geyser, oven and hob, kettle, tumble dryer, heaters and pool pump, because a single one of these can draw more than everything else combined. If you work from home or run medical equipment such as a CPAP machine, tell us. We will make sure those plugs are on backup and size the battery with some margin. You can change the setup later as your needs change, and if you add panels, some heavier loads can run on solar during the day.
Does a backup system need City registration?
If the system can feed power into the grid, or is grid-tied with solar, the City of Cape Town requires SSEG registration. Pure backup systems that never export still need to be installed safely with a CoC. We handle the paperwork either way, so you stay compliant.
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Frequently asked questions
How long will a battery keep my house running?
It depends on what's connected. A 5 kWh battery typically runs essentials (lights, Wi-Fi, TV, fridge) for several hours; 10 kWh can run essentials overnight.
Can a backup system run my geyser or oven?
Usually it's not worthwhile to put them on battery. We keep heavy loads on the grid or on solar during the day, so the battery lasts.
Can I add solar panels later?
Yes. We choose a hybrid inverter so panels can be added later without replacing it.
How long does a battery installation take?
Most backup installs take one day, including DB board changes and testing.
What does battery backup cost?
It depends on inverter and battery size. Send us your essentials list and we'll quote within 24 hours.