One of the most common questions homeowners ask before buying solar is simple: Can solar panels power my house during load shedding?
The short answer is: not necessarily. Solar panels by themselves do not automatically keep a normal grid-connected home running when the electricity supply goes off.
To keep a home powered during an outage, the solar system needs the right combination of a backup-capable inverter, battery storage and electrical changeover or backup configuration. A properly designed hybrid system can continue supplying selected household loads while the grid is unavailable.
This distinction is important because a homeowner can spend money on solar panels and still discover that the house goes dark when the grid fails.
Why do ordinary solar panels stop working during load shedding?
A standard grid-tied solar installation is designed to operate alongside the electricity grid. The inverter uses the grid as its electrical reference and synchronises its output with that supply.
When the grid disappears, the inverter normally disconnects the solar generation. This is part of the system's anti-islanding protection. It prevents a grid-connected solar installation from continuing to energise a network that utility workers may believe is switched off.
That means a house with ordinary grid-tied solar and no suitable backup equipment can still lose power during load shedding, even when the sun is shining.
This is one of the most important differences between grid-tied, hybrid and off-grid solar.
What keeps the house running when the grid goes off?
A backup-capable hybrid system creates a controlled supply for the home when the utility grid is unavailable.
The main components are:
- Solar panels to generate electricity during daylight
- Hybrid inverter to manage solar, battery, grid and backup loads
- Battery storage to provide stored energy when solar production is insufficient
- Backup circuits or distribution arrangement to determine which parts of the property remain powered
- Appropriate protection and changeover equipment as required by the installation
When the grid fails, the inverter isolates the backed-up loads from the grid and supplies them from the available solar and battery sources. The exact behaviour depends on the inverter, battery, system architecture and configuration.
Can solar panels still work while load shedding is happening?
Yes, in a correctly designed hybrid system.
During daylight, the solar panels can produce electricity while the grid is unavailable. The hybrid inverter can use that solar energy to supply the backed-up loads and, where the system allows it and the battery needs charging, send available energy into the battery.
This can make a major difference to battery runtime. If an outage occurs during strong sunlight, the battery may not have to supply the entire household load by itself.
At night, however, there is no solar generation. The battery becomes the primary energy source for the backed-up loads until the battery reaches its configured reserve or the grid returns.
What happens during the day?
Imagine load shedding starts at midday.
Your panels are producing electricity. Your refrigerator, lights, Wi-Fi, computers and other backed-up loads can be supplied from solar generation. If solar production exceeds the immediate load, the available energy can also be used to charge the battery, subject to the system's operating limits and battery state of charge.
This is one reason solar plus battery can be much more capable than a battery-only backup system. The panels can replenish the stored energy while the outage is still taking place.
What happens at night?
Now imagine the same outage occurs after sunset.
There is no solar generation available, so the battery supplies the backed-up loads. How long it lasts depends on the battery's usable capacity and the power being consumed.
A 5kWh-class battery and a 15kWh-class battery are obviously very different backup resources. But battery capacity is only half of the equation. The appliances being operated matter just as much.
Our article How Long Will a Solar Battery Last During Load Shedding? explains the runtime calculation in more detail.
Can a solar system run the whole house during load shedding?
It can be designed to do so in some properties, but whole-house backup is not automatically the best or most economical approach.
Many homeowners choose to back up the circuits that matter most. These may include:
- Lights
- Refrigerator and freezer
- Wi-Fi and internet equipment
- Televisions and entertainment equipment
- Computers and home-office equipment
- Security systems
- Alarm systems
- Gate motors
- Selected plug circuits
High-power appliances can then be managed separately or included only if the inverter and battery system have been designed to support them.
What about the geyser?
An electric geyser is one of the biggest loads in many South African homes. A typical geyser can draw several kilowatts while its element is operating.
That does not mean solar cannot support a geyser. It means the system needs to be designed around that load.
If the geyser is allowed to run during a battery-only outage, it can consume stored energy much faster than lights, a refrigerator and Wi-Fi equipment. Some homeowners therefore choose to keep the geyser off the essential backup circuit and heat water primarily when solar energy is available.
Read Can Solar Run a Geyser, Pool Pump and Air Conditioner? for a closer look at high-power household appliances.
Can solar run a pool pump during load shedding?
It can, provided the system has enough available inverter capacity and the pool pump is included in the backup design.
The important question is whether the pump needs to run during the outage. If it can be scheduled for daylight hours, solar generation can potentially carry much of the load without drawing as heavily on the battery.
This illustrates an important solar principle: when you use electricity can be just as important as how much electricity you use.
What about air conditioners?
Air conditioners can be supported by a suitably sized solar and battery system, but they can represent a substantial load.
A single small air conditioner may be manageable in a properly designed system. Several air conditioners running simultaneously create a very different requirement.
The inverter must be able to handle the simultaneous load, while the battery needs enough usable energy to support the air conditioners for the required period when solar production is low or unavailable.
This is why Solar8 does not size a system simply from the number of bedrooms or the number of solar panels. The actual appliances and their usage patterns matter.
Does a 5kW inverter provide enough backup?
For some homes, yes. For others, no.
A 5kW inverter may be suitable for essential household loads or a relatively modest home, but it may not be able to operate several high-power appliances simultaneously.
An 8kW or 10kW inverter can provide more instantaneous power, but the battery and solar array also need to be matched to the design.
Increasing inverter size alone does not automatically create more backup runtime. The inverter determines how much power can be delivered at a given time; the battery determines how much stored energy is available over time.
Our guide to solar inverter sizing explains this difference.
What is the difference between kW and kWh?
This distinction becomes very important during load shedding.
kW describes power: how much electricity the inverter or appliance needs at a particular moment.
kWh describes energy: how much electricity is stored in the battery or consumed over a period of time.
For example, a battery might have around 10kWh of nominal storage, while the inverter may be capable of supplying 8kW of power. Those numbers describe different things.
A home using a small continuous load may therefore get many hours from a battery, while a home running several high-power appliances can use the same stored energy much more quickly.
What happens when the battery runs low?
A properly configured system normally maintains a reserve rather than allowing the battery to be completely depleted. The exact reserve and shutdown behaviour depends on the battery, inverter and settings.
If the grid is still unavailable and the battery reaches its configured minimum state of charge, the backed-up loads may eventually switch off.
This is another reason system sizing should begin with the question: What do you actually need to keep running, and for how long?
Can solar and battery backup work without Eskom?
Yes, a properly designed off-grid system can operate without a utility connection. But that is a much bigger design requirement than simply adding a few panels to a grid-connected home.
An off-grid property needs enough solar generation and battery storage to cope with periods of low solar production as well as normal household demand. It also needs careful management of high-energy appliances.
For most grid-connected South African homes, a hybrid system can provide a more practical balance of electricity savings, backup and grid support than designing the entire property to operate independently.
What if the load shedding lasts longer than expected?
This is where system design becomes important.
A short outage and a long outage have different requirements. A battery sized for a few hours of essential loads may be perfectly adequate for one household but insufficient for another that wants to run air conditioning, cooking and water heating throughout a prolonged outage.
During daylight, solar generation can extend the backup period. At night, the household needs to rely on stored energy.
Good system design therefore considers both power demand and energy demand.
Can a generator be used with solar and batteries?
In some system designs, yes. A generator can provide another backup source when an extended outage exceeds the practical capacity of the battery and solar system.
Whether this makes sense depends on the property, inverter architecture, generator requirements and the homeowner's priorities.
For many homeowners, however, the first step is deciding how much silent battery backup they actually need before adding another generation source.
Our article Solar Battery vs Generator compares the two approaches in more detail.
How should a home be designed for load shedding?
A good solar assessment starts with the loads, not the equipment catalogue.
Solar8 would look at factors such as:
- Recent electricity consumption
- Monthly electricity bills
- Peak simultaneous loads
- Geyser usage
- Pool and borehole pumps
- Air-conditioning requirements
- Electric cooking
- Heating requirements
- Essential backup circuits
- Desired backup duration
- Roof area and orientation
- Shading
- Electrical supply and phase configuration
- Future electricity requirements
That information allows the system to be designed around the property rather than simply choosing a package because it has a particular inverter size.
Is solar worth it if load shedding is currently limited?
For many homeowners, solar is about more than load shedding.
A hybrid solar system can also reduce the amount of electricity purchased from the grid, shift energy use toward your own solar generation and provide backup when an unexpected outage occurs.
That means the value of the system can come from both electricity savings and energy security.
The best system therefore depends on what you want to achieve rather than on whether load shedding happens every week.
The simple answer: panels alone are not enough
If your home has ordinary grid-tied solar without backup capability, the solar system will generally shut down when the grid goes off.
If your home has a properly designed hybrid inverter, battery storage and backup configuration, the system can continue supplying the designated loads while the grid is unavailable.
During the day, solar can help power the home and recharge the battery. At night, the battery supplies the backed-up loads until the grid returns or the stored energy reaches its configured reserve.
The size of the inverter, battery and solar array should all be matched to the home's actual electricity requirements.
Get a solar system designed for your home
If your main reason for considering solar is load shedding, don't simply ask for the biggest battery or the most panels you can fit on the roof.
Start with the appliances you need to keep running, how long you want them to operate and how much electricity your home normally uses.
Solar8 can assess your electricity consumption, property, appliances and backup requirements and recommend a complete solar system around your needs.
Get My FREE Solar8 Assessment and find out what type and size of solar system makes sense for your home.