If you are considering solar for your home, one of the first decisions is not how many panels you need. It is which type of solar system is right for your property.
In South Africa, the three main choices are grid-tied, hybrid and off-grid solar. They can all use solar panels to generate electricity, but they behave very differently when the electricity grid is available, when the grid goes down and when you want to store energy for later.
The right choice depends on what you are trying to achieve. You may mainly want to reduce your electricity bill. You may want reliable backup during outages. Or you may want to operate independently of the grid altogether.
This guide explains the differences in straightforward terms so you can understand what you are buying before comparing solar quotations.
The three main solar system types
At a high level, the three systems can be thought of like this:
- Grid-tied: solar works alongside the electricity grid, normally without battery storage.
- Hybrid: solar, batteries and the electricity grid can work together.
- Off-grid: the property is designed to operate independently of the electricity grid.
There are many variations within these categories, but this basic distinction is a useful starting point.
What is a grid-tied solar system?
A grid-tied system is connected to the electricity network and uses solar generation to reduce the amount of electricity you need to buy from the grid.
During the day, solar panels generate DC electricity and the inverter converts it into usable AC electricity for the property. Solar power can then supply the home's daytime loads. If the solar system is producing less than the property needs, the grid supplies the difference.
Depending on the equipment, electricity tariff and local rules, surplus generation may also be exported to the grid under an approved small-scale embedded generation arrangement.
The main advantage of grid-tied solar
The major attraction is lower upfront complexity. If your primary objective is reducing daytime electricity purchases, you may not need a large battery bank.
Grid-tied solar can be particularly attractive for a home that uses a lot of electricity during daylight hours, because solar generation can be consumed immediately.
The major disadvantage
A conventional grid-tied inverter normally has to shut down when the electricity grid goes down. This is an important safety function designed to prevent a grid-connected generator from energising lines while utility workers may be working on them.
That means solar panels on their own do not automatically give you backup power during an outage.
What is a hybrid solar system?
A hybrid solar system combines solar generation with battery storage and a connection to the electricity grid.
This gives the system more options for managing electricity. During the day, solar can supply the home and charge the battery. When solar production falls, stored energy can be used. When the battery is depleted or the system needs additional power, the grid can supply the property.
A properly designed hybrid system can also provide backup power to selected circuits or, depending on the equipment and design, a much larger portion of the home during a grid outage.
Why hybrid systems are popular in South Africa
For many homeowners, the attraction is the combination of electricity savings and backup power.
You do not have to choose between using solar to reduce your bill and having batteries for outages. A hybrid system can be designed to do both.
The important point is that battery capacity and inverter capacity still have to match the home's requirements. A hybrid system is not automatically capable of running every appliance in the house during an outage.
What is an off-grid solar system?
An off-grid system is designed to operate without a connection to the electricity grid.
Solar panels generate electricity, batteries store energy and the inverter manages the electrical supply to the property. Because there is no grid available to fill the gaps, the system has to be designed around the property's energy requirements, solar resource and expected periods of low solar production.
Some off-grid properties also use a generator as an additional backup source, particularly where reliable electricity is essential or solar and battery capacity would otherwise need to be very large.
Who is off-grid solar suited to?
Off-grid systems can make sense for remote properties, farms, lodges and other locations where a grid connection is unavailable, unreliable or prohibitively expensive.
For a normal suburban home that already has a reliable grid connection, completely disconnecting from the grid is a much bigger decision. The system needs enough generation and storage to handle periods when solar production is low, not just an average sunny day.
Hybrid vs grid-tied vs off-grid at a glance
| Feature | Grid-tied | Hybrid | Off-grid |
|---|---|---|---|
| Connected to grid | Yes | Yes | No |
| Solar panels | Yes | Yes | Yes |
| Battery storage | Usually no | Yes | Essential |
| Backup during grid outage | Normally no | Yes, if designed for backup | Yes |
| Can reduce grid electricity use | Yes | Yes | Grid not used |
| System complexity | Lower | Medium to high | High |
| Best suited to | Bill reduction and daytime use | Savings plus backup | Independent or remote properties |
This table is a starting point rather than a system specification. Actual performance depends on the equipment, installation and how the property uses electricity.
Which system is best for load shedding?
If backup during electricity outages is one of your main objectives, a conventional grid-tied-only system is generally not enough.
A hybrid system with battery storage is often a more practical choice because it can continue supplying selected loads when the grid is unavailable, provided the inverter and electrical installation are designed for that operation.
The amount of backup you receive depends on the system. A small battery and inverter may be designed for lights, Wi-Fi, refrigeration, security and other essentials. A larger system can be designed to support additional loads.
This is why asking only “How many panels do I need?” is not enough. You also need to ask what do I want to keep running when the grid is off?
Can a grid-tied system work during a power outage?
A standard grid-tied solar system normally cannot continue operating simply because the sun is shining.
The inverter is designed to disconnect from the grid when the grid supply is lost. This prevents unsafe electrical back-feed onto the network.
Some more advanced system architectures can provide backup while remaining connected to the grid when it is available, but that is a different configuration from a basic grid-tied installation.
If backup is important to you, make sure the quotation clearly states which circuits are backed up, how much power is available and how much battery storage is provided.
Which system is best for reducing your electricity bill?
There is no universal answer.
Grid-tied solar can be very effective when a large proportion of your electricity consumption occurs during the day. Solar energy can then be used directly instead of buying as much electricity from the grid.
A hybrid system can provide the same daytime solar benefit while adding the ability to store energy for later use. Whether the additional battery investment makes financial sense depends on your tariff, consumption pattern, backup requirements and how effectively the battery is used.
An off-grid system is a different proposition because its primary goal is energy independence rather than simply reducing a monthly grid bill.
What about batteries?
Battery storage changes the way a solar system can operate.
Without a battery, excess daytime solar may be exported or curtailed depending on the system and local arrangements. With a battery, some of that energy can be stored and used later.
But battery capacity is measured in kWh, while inverter output is measured in kW. These are not the same thing.
For example, a battery may contain enough stored energy to support a home for several hours, but the inverter still has to be capable of supplying the appliances that are operating at the same time.
For more information, see our guides on how much battery storage a home needs and how long solar batteries last.
How your appliances affect the decision
The type of solar system is only one part of the design. Your appliances can have a major influence on the inverter and battery requirements.
- Electric geysers
- Pool pumps
- Air conditioners
- Electric ovens and hobs
- Heaters
- Washing machines and tumble dryers
- Borehole and pressure pumps
- Electric vehicle chargers
A home with modest loads may need a very different system from a larger property where several high-power appliances can operate at the same time.
Our guide on running geysers, pool pumps and air conditioners from solar explains this in more detail.
Do you have to disconnect from Eskom to use solar?
No.
Most residential solar systems in areas with an existing electricity connection remain connected to the grid. The solar system works alongside the grid and reduces the amount of electricity purchased from it.
A hybrid system can also remain grid-connected while using batteries for backup and energy management.
Going completely off-grid is a much more significant decision because the property can no longer rely on the grid to cover periods of low solar generation or high demand.
What about Eskom and municipal approval?
If your solar system operates in parallel with the electricity grid, compliance and registration requirements can apply. The exact process depends on the electricity distributor serving the property.
Eskom states that grid-connected small-scale embedded generation systems need to be registered with the relevant network service provider, while a genuinely stand-alone system that is completely independent of the grid is treated differently. Municipal customers should check their own distributor's requirements.
This is another reason to use a competent installer and make sure the quotation includes the appropriate compliance and certification requirements.
Do not assume that a system is automatically legal simply because the equipment is sold commercially.
What system should you choose?
A useful way to think about the decision is to start with your main objective.
Choose grid-tied when your priority is bill reduction
If your main goal is to reduce electricity purchases and you are comfortable remaining dependent on the grid during outages, a grid-tied system may be worth considering.
It can be particularly attractive where there is substantial daytime electricity consumption.
Choose hybrid when you want savings and backup
If you want to reduce your electricity bill but also want protection from power interruptions, hybrid is often the most flexible option.
The key is to size the battery and backup circuits around what you actually need rather than simply buying the largest battery available.
Choose off-grid when independence is the objective
If there is no practical grid connection or you deliberately want to operate independently, an off-grid system can be appropriate.
It requires more careful energy planning because the grid cannot step in when solar production is poor or demand is unexpectedly high.
What should you ask before accepting a solar quote?
- Is the system grid-tied, hybrid or genuinely off-grid?
- What happens when the grid goes down?
- Which circuits receive backup?
- What is the inverter's continuous output?
- What is the battery's usable capacity?
- How much solar generation is included?
- What happens to excess solar generation?
- Is grid registration or municipal approval required?
- What electrical protection and compliance work is included?
- What warranties apply?
- Can the system be expanded later?
These questions can reveal major differences between two quotations that appear similar at first glance.
There is no single “best” solar system
The best solar system is the one that matches the property, the household's electricity usage and the reason for installing solar.
A grid-tied system can be an excellent choice for reducing daytime electricity costs. A hybrid system can add valuable battery backup and energy management. An off-grid system can provide genuine independence where the property and budget justify it.
The mistake is choosing the system type first and trying to make the property fit it afterwards.
Find the right solar system for your home
If you are in Pretoria, Johannesburg, Gauteng or elsewhere in South Africa, Solar8 can assess your electricity usage, appliance loads, backup requirements, roof space and future plans before recommending a system.
We can help you understand whether grid-tied, hybrid or off-grid makes sense for your property and what the complete system needs to achieve your goals.
Get My FREE Solar8 Assessment and let us help you choose the right solar system for your home.