Planning solar and backup power into a renovation

Eskom suspended load shedding on 26 March 2024, and at the time of writing the lights have stayed on for more than five weeks. After the past few years, though, very few homeowners we speak to are taking power for granted. Solar panels and batteries are now part of almost every renovation conversation. If you are renovating anyway, it is the best time to plan for them properly.

Why plan it during a renovation?

Retrofitting solar to a finished house means surface-mounted trunking, cables running across ceilings and an inverter mounted wherever there is space. During a renovation, you can:

Run conduits and cables while walls and ceilings are open
Create a proper, ventilated space for the inverter and batteries
Rewire the distribution board so essential circuits are separated
Design the roof with panels in mind: orientation, structure and access

Essential and non-essential circuits

Most homes do not back up everything. A typical setup separates essential circuits (lights, plugs for the fridge, Wi-Fi, TV, gate and alarm) from heavy loads such as the geyser, oven, hob, pool pump and underfloor heating. Splitting the distribution board this way during a rewire is simple. Doing it later is messier.

Choosing the system

There are three common setups:

Backup only: an inverter and battery that charge from the grid and supply essential circuits when the power goes off. No panels.
Hybrid solar: panels, an inverter and batteries. The panels reduce your daytime electricity use and charge the batteries.
Grid-tied with feed-in: a solar system that can also export excess power to the City’s grid, if approved.

The right size depends on how you use power, the size of your roof and your budget. A reputable installer will look at your past electricity bills before recommending a system.

The City of Cape Town rules

In Cape Town, all small-scale embedded generation (SSEG) systems, including solar PV and inverters with batteries that connect to your home’s electrical installation, must be registered with and authorised by the City before installation. This is about safety: a system feeding power back into the grid during an outage can endanger workers repairing the lines.

The process involves an application with the system’s technical details, approval to install, and after installation, a commissioning report and certificate of compliance. Use an installer who handles the registration for you and uses approved inverters.

Panels on a pitched roof generally do not need building plans, but large ground-mounted arrays or structures may. Heritage areas can have their own rules about visible panels.

The roof

Panels are heavy and add wind loads. Your roof structure must be able to carry them, and the fixing of the mounting rails must not compromise the waterproofing. On a new roof, coordinate the panel layout with the roof sheeting or tiles before installation.

The inverter and battery space

Inverters and lithium batteries should be installed in a dry, ventilated space, away from bedrooms, and in line with the manufacturer’s requirements. A garage, utility room or purpose-built cupboard is ideal. Plan this space during design.

Our role

We coordinate with accredited solar installers during renovations so the wiring, roof and installation space are ready when they arrive. If you are planning a renovation and want to include solar, let us know at the start.