If you have never owned a solar system before, the basic idea can seem complicated. In reality, the energy journey is fairly straightforward: sunlight is converted into electricity, the inverter manages that electricity, your home uses it, and a battery can store some of it for later.
What makes a modern solar system more sophisticated is the way those components work together with the electricity grid. A good system can automatically use solar when it is available, charge the battery when appropriate, draw from the battery later, and use grid electricity when solar and stored energy are not enough.
This guide explains how solar power works for a typical South African home without getting buried in electrical engineering terminology.
The basic solar electricity journey
A typical home solar system follows a simple sequence:
- Sunlight reaches the solar panels.
- The panels produce DC electricity.
- The inverter converts and manages that electricity.
- Your home uses the available power.
- Extra solar energy can charge the battery if battery storage is installed.
- The battery can supply the home later when solar production is lower.
- The grid supplies any remaining shortfall when required on a grid-connected system.
The exact flow depends on whether the system is grid-tied, hybrid or off-grid, but these are the building blocks behind most residential installations.
What do solar panels actually do?
Solar panels convert sunlight into direct current (DC) electricity. Each panel contains photovoltaic cells that respond to sunlight and generate electrical power.
A panel's wattage tells you its rated power under specified test conditions. For example, a 550W panel is designed to produce up to roughly 550 watts under its rated conditions. It does not mean that the panel produces 550W continuously from sunrise to sunset.
Actual production changes throughout the day because of sunlight intensity, panel temperature, orientation, shading, cloud cover, dust and other system losses.
This is why a solar array's kWp rating and its actual daily kWh production are two different things.
Why do you need an inverter?
Your home's normal electrical appliances use alternating current (AC). Solar panels produce DC electricity, so an inverter is required to convert and manage the power so that it can be used by the property's electrical system.
Modern solar inverters do much more than simply convert DC to AC. Depending on the type of inverter and system, it can manage solar generation, household demand, battery charging and discharging, grid electricity and backup circuits.
The inverter is therefore one of the most important components in a solar installation. Its capacity also needs to match the property's electrical requirements and the planned solar and battery configuration.
What happens to solar power during the day?
Imagine a home on a sunny afternoon. The panels are producing electricity while the household is using power.
The solar energy is first available to supply the home's electrical demand. If the house is using 2kW and the solar system is producing 4kW at that moment, approximately 2kW is available for other uses, depending on the system configuration.
If a battery is installed, the surplus can be used to charge it. Once the battery reaches its configured state of charge, the system may reduce solar production or, where permitted and configured, export excess electricity to the grid.
This is one reason household consumption patterns matter when designing a system. Producing more solar power does not automatically mean that every extra unit will translate into an equal reduction in your electricity bill.
What happens when the sun goes down?
Solar panels stop producing meaningful electricity when there is no sunlight. At that point, a battery-equipped system can use stored energy to supply the home.
If the battery does not have enough usable energy for the remaining demand, a grid-connected system can draw electricity from Eskom or the municipality. The exact behaviour depends on the inverter settings and the system's operating mode.
This is where battery storage becomes particularly useful. It allows some of the electricity generated during the day to be shifted into the evening and night.
How does a solar battery work?
A solar battery stores electrical energy so that it can be used later. During periods of surplus solar production, the inverter directs suitable power into the battery. Later, the battery discharges through the inverter to help supply the property's loads.
Battery capacity is normally discussed in kilowatt-hours (kWh). A battery's rated capacity is not necessarily the same as the amount of energy that should routinely be used from it, because manufacturers may specify usable capacity, depth-of-discharge limits and other operating conditions.
Battery size therefore needs to be considered alongside the loads you want to run and how long you want them to operate during periods without solar or grid supply.
What happens during a power outage?
This depends heavily on the type of solar system.
Grid-tied solar during an outage
A standard grid-tied inverter normally shuts down when the grid fails. This is an important safety feature designed to prevent a solar installation from feeding electricity into a grid that utility workers may believe is de-energised.
As a result, solar panels alone do not normally provide backup power during a grid outage.
Hybrid solar during an outage
A correctly designed hybrid system can isolate the property's backup circuits from the grid and continue supplying them from the battery and available solar generation.
The homeowner may therefore continue using selected lights, refrigeration, internet equipment, security systems and other essential loads while the grid is unavailable. Which appliances can run depends on the inverter capacity, battery capacity, solar production and the circuits included in the backup system.
Off-grid solar during an outage
An off-grid system is designed without relying on the utility grid as its normal energy source. Solar panels and batteries must therefore be sized to supply the property through normal usage and periods of lower solar production.
Because there is no grid fallback, off-grid design requires particularly careful attention to energy consumption, battery capacity, solar generation and high-power appliances.
Grid-tied, hybrid and off-grid: what is the difference?
The simplest way to understand the three approaches is to look at what each system is designed to achieve.
- Grid-tied: solar is used mainly to reduce electricity purchased from the grid.
- Hybrid: solar, battery storage and the grid work together, providing both energy savings and backup capability.
- Off-grid: the property is designed to operate independently of the utility grid.
For many South African homes that already have a reliable grid connection, a hybrid system can offer a useful balance between savings and backup. But there is no universal answer: a daytime-heavy household with little need for backup may have different requirements from a home where evening consumption and backup are major priorities.
What is the difference between kW and kWh?
This is one of the most important solar concepts to understand.
kW describes power — the rate at which electricity is being produced or consumed at a particular moment.
kWh describes energy — how much electricity has been used or generated over a period of time.
For example, a home may have several appliances drawing a combined 4kW at one moment. Over several hours, those appliances could consume many kWh of energy.
This distinction matters because inverter sizing is strongly related to power demand, while battery sizing is strongly related to stored energy and how long loads need to operate.
Why can't you simply run every appliance from solar?
It depends on the size and design of the system.
A home can have a large solar array but still have an inverter that limits the amount of power available at one time. Likewise, a large battery can store substantial energy without necessarily being able to deliver unlimited instantaneous power.
High-power appliances such as geysers, electric ovens, pool pumps, air conditioners and heaters can create significant loads. If several of them operate simultaneously, the inverter and electrical installation must be capable of handling the combined demand.
This is why proper system sizing looks at the home's actual and expected loads rather than choosing equipment based on panel count alone.
Where does the electricity go?
A useful way to think about a hybrid solar system is that the inverter is continuously managing several possible energy sources and destinations.
- Solar → Home: solar power supplies appliances directly.
- Solar → Battery: surplus solar charges the battery.
- Battery → Home: stored energy supplies the property later.
- Grid → Home: the utility supplies energy when required.
- Solar → Grid: surplus may be exported where the applicable rules and system configuration permit it.
The priority order can be configured differently depending on the inverter, battery, tariff structure and homeowner's objectives.
Does solar mean you can disconnect from Eskom?
Not necessarily.
A grid-connected home can use solar to reduce its electricity purchases without becoming fully independent of the grid. In many cases, keeping the grid connection provides useful backup when solar production and battery storage are insufficient.
Going fully off-grid is a different design objective and normally requires more generation and storage capacity, particularly if the home has substantial electricity demand or needs reliable power through extended periods of poor solar production.
How much solar does a home actually need?
There is no single panel count or inverter size that is correct for every South African home.
A proper system design considers your electricity usage, when you use it, the appliances you want to run, your backup requirements, available roof space, shading, electrical supply and future plans.
Your monthly electricity bill is a useful starting point, but it does not tell the whole story. Two homes with similar monthly bills can have very different load profiles and therefore require different solar and battery configurations.
For that reason, Solar8 recommends sizing the complete system around the property rather than simply choosing a popular inverter size or a fixed number of panels.
What happens to excess solar energy?
If the solar array is producing more energy than the home is using, the system has several possible options.
It may charge the battery, supply additional loads such as a geyser where appropriate, reduce generation once the available demand and storage capacity have been satisfied, or export energy to the grid where the applicable utility rules and installation approvals allow this.
Exactly what happens depends on the inverter, battery, control settings, utility requirements and the property's electricity connection.
Why system design matters more than individual components
It is easy to compare solar systems by looking only at the panel wattage, inverter brand or battery capacity. Those numbers matter, but they do not tell you whether the complete installation is right for your home.
A properly designed system needs the panels, inverter, battery, protection equipment, mounting structure, cabling and electrical installation to work together safely and efficiently.
It should also account for the property's actual energy requirements rather than relying on a generic package that may be too small for your needs or unnecessarily large for your usage.
What information should you have before getting a solar quote?
The more accurately your installer understands the property, the better the system can be sized.
- Your recent electricity bills or consumption history
- Whether the property is single-phase or three-phase
- The appliances you consider essential
- Which appliances are used during the day and at night
- Your desired backup duration
- Whether you want bill reduction, backup, or both
- Available roof space and any obvious shading
- Whether you may want to expand the system later
This information gives a solar installer a much better basis for recommending the right combination of panels, inverter and battery storage.
Solar power in simple terms
The easiest way to remember how a home solar system works is:
Solar panels make electricity. The inverter manages it. Your home uses it. The battery stores it for later. The grid supplies any remaining shortfall.
Once you understand that basic flow, the rest of solar system design becomes much easier to understand.
The challenge is choosing the right size and configuration for your particular property. That is where a proper assessment becomes more useful than simply buying the largest inverter or the highest number of panels you can fit on the roof.
Ready to find out what solar system your home actually needs?
Solar8 can help you work through your electricity usage, backup requirements and property details to determine a practical solar solution.
Instead of starting with a fixed package, start with the property and let the system be designed around what you actually need.
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