Fast read
As Australia retires its fleet of coal-fired power stations, which have historically provided a constant power supply, the grid needs new ways to ensure electricity is available 24/7. Solar panels only generate power during the day, creating variability. Home batteries solve this by storing that daytime solar energy and releasing it during evening peaks, helping to smooth out supply, reduce strain on the grid, and ensure a reliable, clean energy system for the future.
Why are more solar home batteries required when we close the coal-fired power stations?
It’s a question many Australians are asking as they see the nation’s energy landscape shift. For decades, large coal-fired power stations have been the backbone of our electricity grid. Now, as they are gradually phased out, there’s a growing conversation about the role of solar home batteries. The connection between these two events is central to understanding Australia’s transition to a renewable energy future.
This shift isn’t just about replacing one form of generation with another; it’s about building a smarter, more resilient, and decentralised grid where homeowners play a vital role.
What role have coal power stations played in our grid?
For most of Australia’s history, coal-fired power stations have provided what is known as “baseload” power. This is a constant, steady supply of electricity that runs 24/7 to meet the minimum energy demand of the grid. These large, centralised plants were designed to run continuously because they are slow to start up and shut down.
Beyond just generating power, their massive spinning turbines have also provided essential “system strength” or inertia. This physical momentum helps keep the grid’s frequency and voltage stable, acting like a shock absorber for sudden changes in supply or demand. As these aging plants retire—a trend accelerated by economic pressures and reliability concerns—the grid loses both a major source of power and a key stabilising force.
The challenge of replacing constant power with renewables
The primary challenge in moving away from coal is the difference in how renewable sources like solar and wind generate power. Unlike coal, their output is “variable” or “intermittent”, meaning they only produce electricity when the sun is shining or the wind is blowing.
This variability creates two main issues for the grid:
- A supply and demand mismatch: Solar panels generate vast amounts of cheap, clean energy during the middle of the day. This often exceeds demand, creating a surplus. In the evening, as the sun sets, solar generation plummets just as households turn on their lights, appliances, and televisions, causing a sharp spike in demand that needs to be met by other sources.
- Grid instability: Without the inertia from large turbines, the grid becomes more vulnerable to fluctuations in frequency and voltage, which can risk blackouts if not managed carefully.
This is the core problem that needs solving as we transition to a grid dominated by renewables.
How do solar home batteries solve this problem?
This is where solar home batteries step in, providing a powerful solution at both the individual household and wider grid level.
A home battery system, such as a Sungrow SBR or Tesla Powerwall, essentially allows a household to capture and store the excess solar energy generated during the day instead of sending it all back to the grid. This stored energy can then be used in the evening, directly reducing the home’s reliance on the grid during those critical peak demand hours.
By using your own stored solar power at night, you are actively helping to flatten the evening demand spike. When thousands of homes do this simultaneously, it significantly reduces the overall strain on the national grid.
The power of many: from a single home to a stable grid
The true power of home batteries is realised when they are connected and coordinated. This is the concept behind a Virtual Power Plant (VPP). A VPP is a cloud-based network that links hundreds or thousands of individual home batteries, allowing them to be managed as a single, large-scale energy resource.
When orchestrated by a VPP operator, this network of batteries can provide the essential services to the grid that were once the exclusive domain of coal plants:
- Firming renewables: Batteries can discharge energy to “firm up” or smooth out the variable output from large-scale wind and solar farms, ensuring a more consistent supply.
- Peak shaving: During extreme demand peaks, like on a hot summer afternoon, the VPP can draw a small amount of power from each connected battery and feed it into the grid. This reduces the need to fire up expensive and polluting gas “peaker” plants.
- Frequency regulation: Modern batteries can respond in milliseconds to stabilise grid frequency, helping to prevent blackouts far faster than traditional generators.
By participating in a VPP, homeowners not only support the grid but can often earn credits on their electricity bills for doing so.
Are home batteries the only solution?
It’s important to recognise that solar home batteries are one crucial piece of a much larger puzzle. Australia’s energy transition, as outlined in plans by the Australian Energy Market Operator (AEMO), relies on a diverse mix of technologies.
Alongside home batteries, the future grid will be supported by:
- Utility-scale batteries: These are very large battery installations, often located at former power station sites or alongside solar farms, that can provide grid-scale storage and stability.
- Pumped hydro: These projects act like giant water batteries, using excess renewable energy to pump water uphill and releasing it through turbines to generate power when needed.
- Transmission upgrades: Significant investment is needed to build new high-voltage transmission lines to carry renewable energy from solar- and wind-rich zones to our cities.
Together, these solutions create a flexible and resilient energy system capable of managing the transition from fossil fuels to clean energy.
A cleaner, more resilient future
The closure of coal-fired power stations marks a fundamental shift for Australia’s energy system. Filling the gap they leave isn’t just about replacing their raw power output; it’s about replacing their role in providing 24/7, on-demand, stable electricity.
Solar home batteries are uniquely positioned to address this challenge. They empower homeowners to become active participants in the new energy system, storing cheap solar power for their own use while also contributing, often through VPPs, to the overall stability and reliability of the grid. As we move towards a future powered by renewables, the role of home batteries will only continue to grow in importance, paving the way for a cleaner, more affordable, and resilient energy network for all Australians.
