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The transition from burning fossil fuels like coal and natural gas to generate electricity to renewable energy sources like wind, hydropower, and solar is a global priority.
Both on the power grid and industrial level — and on a much smaller scale.
Solar photovoltaics are by far the most widely used grid-connected renewable energy system for residential use and can provide welcome protection from load-shedding.
But for some homeowners, small wind turbines and micro-hydropower may be viable alternatives.
What grid-tied electricity generation system is the best choice for you?
Read on to find out.
What Are Grid-Connected Renewable Energy Systems?
All currently available sources of renewable energy are, by nature, intermittent.
Turbines don’t generate electricity when there’s no wind.
Solar panels don’t work at night.
Intermittency is a challenge both at the residential level and at a utility-scale.
Wind farms, hydro turbines and solar farms generate massive amounts of electricity to feed the power grid.
Utilities must either store the electricity that solar panels and turbines produce for times when demand or supply or supplement renewable energy with nuclear power or fossil fuels.
You’ll face a similar challenge if you want to switch to generating all or part of your household electricity with renewable energy.
One option is to store the electricity you generate with solar panels or a small wind turbine in batteries for later use.
The other alternative is to connect your residential system to the utility grid.
How Do Grid-Connected Renewable Energy Systems Work?
Residential solar power, small wind energy, and micro-hydropower systems solve the challenge of intermittency by connecting to the utility grid.
The mechanics of how solar, wind, and hydropower systems connect to the grid differ based on the type of system you choose.
But the basic principles are the same.
For example, with a residential photovoltaic (PV) solar power system, your home runs on the electricity captured by PV modules, like solar panels or shingles.
When your consumption exceeds the electricity supply from your solar power system, a bidirectional meter or transfer switch automatically toggles to draw electricity from the grid.
In some locations, you may be eligible for net metering schemes.
(Source: Vermont.gov)
Net metering is a billing mechanism that allows you to sell and transmit the electricity you don’t consume directly to the grid.
In South Africa, it’s frequently known as “feeding in” or net billing.
Net billing isn’t widely available (yet), but that’s changing.
Feeding in is unlikely to turn a profit, but it can reduce the cost of electricity consumed from the grid and decrease your solar payback period.
Grid-connected renewable energy systems typically cost less upfront than off-grid power solutions.
Unfortunately, no matter which type of on-grid system you choose, they all have a substantial drawback.
Grid-tied solar, wind, and hydroelectric systems automatically shut down during a blackout and must remain offline until power is restored to the grid.
If you’re investing in clean, renewable power to provide home backup power during Eskom load-shedding and blackouts, a hybrid solar system with battery storage is a much better solution than being tied to the grid.
Different Types of Grid-Connected Systems
For most individuals, families, and small businesses, solar photovoltaic grid-tied, hybrid, or off-grid systems are the best choice for generating electricity from a renewable energy source.
However, small wind turbines or micro-hydropower could be viable options depending on your location and other factors related to your property.
Residential solar power systems may be eligible for federal, provincial, and municipal government incentives.
Unfortunately, only businesses can claim tax credits for wind or hydro projects.
Let’s take a closer look at the three main types of grid-connected renewable energy systems.
(Source: Energy.gov)
Micro-Hydropower
If you have a river or other fast-moving body of water running through your property, a small hydropower system may be able to power at least part of your home.
Micro-hydropower systems can produce up to 10 kilowatts of electricity, but according to the US Dept. of Energy, most “generate up to 100 kilowatts.”
Micro-hydropower turbines and generators are typically sold as a package by professional installers.
(Source: NREL)
Even at a utility scale, hydro-power hasn’t gained much traction.
In 2023, only 0.5% of Eskom electricity was generated with hydropower.
Residential micro-hydro systems are extremely uncommon.
Total Wind Energy Capacity in South Africa From 2013 to 2023 (in Megawatts)
(Source: Statista)
Small Electric Wind Systems
Wind is an abundant resource in some parts of South Africa, and utility-scale turbine farms generate an increasingly significant portion of the nation’s electricity.
However, small wind electric systems for residential or small business use are only viable for a tiny segment of property owners.
The US Department of Energy estimates that you need a minimum of one acre of unobstructed land to install a wind turbine that has the potential to produce 5kW-15kW of electricity output.
That pretty much rules out anyone in urban areas.
Even on large plots of land, zoning and building permissions for wind turbines are strict for many reasons, including the elevation required and the substantial footprint.
If none of the above restrictions apply, a small electric wind system could be a workable option.
However, like micro-hydro, small wind energy systems are rare in South Africa.
Solar Photovoltaic
At the utility-grid level, wind generates almost twice as much electricity as solar photovoltaic in South Africa.
However, when it comes to residential clean energy systems, it’s not even close.
(Source: Energy Monitor)
Rooftop solar adoption skyrocketed 349% between March 2022 and June 2023.
The ongoing misery of load-shedding and falling prices of solar panels have led more and more consumers and businesses to invest in rooftop PV systems.
In February 2023, the federal government instituted a 15% tax credit for purchases of new solar panels (capped at R15,000 per taxpayer), which likely helped spur adoption.
Despite the global climate emergency, a transition to clean, renewable power is yet to gain momentum on a national level.
Electricity Generation in South Africa by Source (2023, in Terawatt Hours)
(Source: Stellenbosch University)
An overwhelming 82.8% of Eskom power is generated by burning coal — by far the worst electricity generation source for the environment.
(Source: Global Solar Atlas)
Despite an abundant solar resource and significant government funding, utility-scale PV projects have been slow to come online
More and more individuals and business owners are taking matters into their own hands by installing rooftop PV systems to reduce their reliance on Eskom, resulting in electricity bill savings and energy security.
As the price of solar power systems continues to fall and electricity bills rise, the return on investment can be substantial.
The popularity of solar photovoltaic systems for residential applications is largely due to their ease of installation, affordability, flexibility, and minimal regulations regarding their use.
Unlike small wind turbines and micro-hydro systems, many off-grid and hybrid solar power solutions don’t require professional installation or permission from government agencies.
However, all grid-connected renewable energy systems require professional installation and the cooperation of your utility provider.
We’ll get into the various additional requirements for each type of system below.
What Equipment Is Needed for Grid-Connected Renewable Energy Systems?
All renewable energy systems require:
- Adequate supply of the requisite power source: wind, hydro, or sunlight
- A means of capturing energy: e.g., wind and hydro turbines or solar panels
- Balance of system to convert mechanical, rotational, or photovoltaic power into electricity and condition it for use by the consumer and (potentially) to be sent back to the grid
- A reliable connection to the utility grid
- Safety equipment
- A net meter, bidirectional meter, smart meter, or other instrument compliant with your utility provider
- Zoning and building permits
The actual components used in each type of system vary by energy source.
Here’s a summary of the typical components used in each.
Micro-hydropower System Components
- Water conveyance: A channel or pipeline to intake water and deliver it to the powerhouse
- Turbine, pump, or waterwheel: Captures rotational energy from flowing water
- Alternator: Transforms rotational power into direct current (DC) electricity
- Inverter: Converts DC to 120V or 240V AC (household) electricity
- Regulator: Monitors and controls the generator
- Cables and wiring: Transmits electricity to your home
(Source: Green Mechanic)
Small Wind Electric System Components
As the diagram above shows, even small horizontal wind turbines have a substantial number of components.
Rather than describing what each individual part does, let’s focus on the essentials.
- Blades and rotor: The distinctive propeller-shaped turbine blades and rotor are spun by the wind to produce mechanical energy.
- Pitch
- Brakes
- Low-speed shaft
- Gearbox
- Alternator (Generator): The alternator (or generator) works in a similar way to its equivalent in hydroelectric systems. It converts mechanical energy into electricity.
- Wind vane
- Nacelle
- High-speed shaft
- Yaw drive
- Yaw motor
- Tower: To take advantage of the wind resource at your location and make a small wind electric system viable, the US DoE says, “Your turbine needs to be sited upwind of any buildings and trees, and it needs to be 30 feet above anything within 300 feet.”
Solar Photovoltaic System Components
- Photovoltaic modules (solar panels or shingles): PV cells — typically made from monocrystalline or polycrystalline silicon — capture sunlight and transform it into electricity using the photovoltaic effect.
- Solar Inverter
- Solar battery*: Stores DC electricity for when your consumption exceeds production and for backup power during a blackout. Sealed lead acid (SLA), lithium-ion (Li-ion), and lithium iron phosphate (LiFePO4/LFP) solar battery chemistries are the most common, with LFP offering the best performance.
- Charge controller*: Regulates storage, prevents under and overcharging, and optimises battery efficiency
- Battery management system*: Maximizes battery performance and lifespan.
- Transfer switch or Smart Home Panel for integration with your home circuit board
- Auto-disconnect for power outages (or auto-switchover for hybrid systems)
- Bidirectional or smart meter
- Mounting hardware for rigid solar panels
- Cables and wiring
*For hybrid solar + storage systems
What Are the Planning and Installation Requirements for Grid-Connected Renewable Energy Systems?
Connecting a wind, hydro, or solar power system to the utility grid has its benefits.
It resolves the challenge of the intermittent nature of renewable energy sources — except during blackouts.
The fact that all grid-connected renewable energy systems must either shut down or auto-switch to battery power during an outage clearly indicates the dangers of an unstable or faulty connection to the utility grid.
Most grid-connected renewable energy systems are bidirectional.
You consume power from the grid when your electricity product is insufficient, AND you transmit electricity to the utility when you generate more than you need.
If you don’t supply electricity to the grid through dual metering or feeding-in, any excess power your system produces simply goes to waste.
In a blackout, electricity transmitted through the power lines from grid-tied systems could injure or kill workers trying to restore power or cause further damage to the utility infrastructure.
Off-grid and hybrid solar generators and portable power stations don’t require a direct connection to the grid and, in many instances, don’t require the involvement of your utility provider or planning authorities.
However, bidirectional grid-connected renewable energy systems are strictly regulated and typically require utility provider approval, building permits, and zoning permission.
Regulations vary by location, but here’s a brief overview of what you can expect.
Requirements for Micro-hydropower Systems
If you have a river or other fast-moving body of water flowing through your property, micro-hydro might be an option — if local regulations allow it.
(Source: Natural Resources Canada)
You can estimate the amount of electricity you can generate from flowing water on your property by measuring the following:
- Head: The height water falls from
- Flow: The volume of water falling
There are numerous ways to determine the head and flow at your occasion, including the weighted-float or the bucket method.
Once you’ve determined your electricity generation capacity, you can assess whether investing in micro-hydropower makes economic sense.
Be sure to factor in any available government incentives.
If the numbers add up in your favour, you’ll still have to do a considerable amount of legwork.
Unfortunately, most parts of South Africa don’t have sufficient fast-running water sources to make micro-hydro viable for homeowners.
Luckily, we have a bountiful supply of sunlight!
(Source: Global Wind Atlas)
Requirements for Small Wind Energy Systems
The two biggest requirements for residential small wind energy systems are a sufficient wind resource and space on your property.
The US DoE estimates that a wind turbine must provide at least 5kW-15kW of electricity generation potential to be financially viable.
A turbine that size requires about one acre of unobstructed land — a substantial footprint on almost any property.
If your property meets the above requirements, assess whether the electricity the wind turbine can generate will justify your investment over time.
There are numerous free online tools that everyone, from policymakers to homeowners, can use to estimate wind energy potential by location.
Next, consult your provincial and local planning authorities to determine whether turbine construction and installation are allowed on your property.
Wind turbines require a considerable footprint on your property, and the tower on which the turbine blades and rotor are mounted must be a significant height.
According to the US DoE, “Your turbine needs to be sited upwind of any buildings and trees, and it needs to be 30 feet above anything within 300 feet.”
To install a grid-connected small wind power system, you’ll need permission from multiple authorities and compliance with numerous regulations.
Unfortunately, it’s not a straightforward process.
Small wind turbine systems are regulated at the provincial or municipal level.
For example, Cape Town recently proposed new guidelines for small wind turbine systems.
Wind energy can play a crucial role in transitioning away from fossil fuels, but it’s much more practical at a utility scale than for home installation.
Requirements for Grid-Tied Solar Photovoltaic Systems
As with wind and hydro, the first step in determining your requirements for a solar photovoltaic system is assessing whether you receive sufficient energy at your location to provide a solid return on investment.
(Source: Global Solar Atlas)
The Global Solar Atlas provides a variety of maps and other tools to help you estimate the amount of sunlight your location will receive based on historical data.
Because PV modules collect photons from sunLIGHT using the photovoltaic effect — not from heat — your solar panel array will generate the most electricity under direct sunlight.
Extreme temperatures actually have a negative effect on solar panel efficiency.
Once you’ve estimated your electricity generation potential and the cost of your system, you can determine whether it makes financial sense.
The legal and technical barriers to installing solar photovoltaic systems are substantially lower than those of wind turbines or micro-hydropower.
Many homeowners choose rooftop installations with rigid solar panels, as they leave no additional footprint on your property.
Ground installations with rigid or portable solar panels may also be viable.
Off-grid solar generators that provide whole-home backup power, like EcoFlow DELTA Pro, don’t require professional installation or permits—unless you’re connecting one to your home circuit board with a transfer switch.
EcoFlow DELTA Pro is a hybrid solar + storage system that provides multiple charging options, including solar panels and utility grid (AC) power.
However, it’s not eligible for net metering programs as it doesn’t transmit electricity to the utility grid.
Grid-tied solar photovoltaic systems that consume and transmit electricity to your utility provider have additional requirements.
But far less than wind turbines or hydropower.
Here’s what you’ll need to do to install a grid-connected solar photovoltaic system:
- Check with your utility provider or power company to make sure they offer grid connection for solar
- Thoroughly examine your power provider’s requirements
- Ensure that the photovoltaic modules, solar inverter, and other balance of system components meet your utility provider’s compliance standards
- Is net metering or feed-in tariffs available at your location?
- Does your local authority have restrictions on rooftop or ground solar panel installations?
- It may or may not be mandatory in your location (yet), but it’s a best practice to ensure your system and installation follow one (or more) of the following standards.
- IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems (IEEE 1547-2003)
- Underwriters Laboratories certification for solar inverters and other balance of system components (UL 1741)
- Apply for building permits (if required)
- Hire a professional installer to help ensure compliance and optimise performance
- Hire a licensed electrician to connect your PV system to the utility meter and your home wiring
- Follow any certification and inspection requirements
Many of the steps above can be simplified or avoided if you opt for an off-grid or hybrid solar photovoltaic system rather than a traditional grid-tied setup.
Unfortunately, grid-connected residential PV systems are relatively rare in South Africa, although NERSA is considering a new net-billing framework that should make feeding-in more accessible to homeowners.
In the meantime, legal firm Clyde & Co. recently said:
“Navigating the solar energy regulations in South Africa is like moving through a bureaucratic maze to try and find one’s way out of a pitch-black room with only a flashlight made of red tape.”
There’s definitely room for improvement!
Final Thoughts
Renewable energy is rapidly growing as an electricity generation source — both at the utility and the residential level.
Solar photovoltaic and solar thermal systems are by far the best options for home applications.
Whether you connect to the grid directly or opt for a hybrid solar + storage solution like EcoFlow DELTA Pro, it’s never been a better time to switch to solar.
Save money on electricity bills and enjoy home energy security…
Check out EcoFlow’s solutions today.