Solar trumps Nuclear

With the coalition bringing nuclear energy into the limelight, there are lots of questions being raised regarding the relationship between nuclear and solar. Is solar or nuclear energy better? Which offers the better alternative to coal-fired power? Is nuclear more expensive than solar? 

Let’s weigh up the pros and cons of nuclear energy and solar energy to determine which is the better solution for Australia - the answer may surprise you.

Why are we weighing up solar versus nuclear?

As we trudge our way to the next Australian federal election set for mid-2025, the Coalition has declared their plans for a ‘nuclear Australia’. You may have heard the Leader of the Opposition, Peter Dutton, outline his vision to build seven nuclear power plants across five Australian states, utilising a mix of small modular reactors (SMRs) and large-scale nuclear plants. 

Should the coalition win the 2025 election, their first call to action on Australia’s energy mix is to halt the current renewable energy transition (largely spearheaded by solar PV, wind, and hydro) in favour of building nuclear power plants in existing or former coal-fired power stations. 

Given this context, it appears that solar and nuclear are at war. What would it mean for Australia’s renewables landscape should nuclear come into play? And how would it affect rooftop solar owners? Unfortunately, should nuclear be introduced to the energy mix, it would likely result in some significant negative changes for those with solar… Not to mention, the drastic shifts to Australia’s Net Zero targets. 

The argument of solar versus nuclear begs the question: with climate change being proclaimed as the “defining issue of our time”, which energy source aligns best with the 2015 Paris Agreement?

Solar versus nuclear at a glance

Australia's current energy mix

Australia’s current energy landscape consists largely of fossil fuels, with coal, gas, and oil generating 68% of Australia’s electricity in 2022. Renewables, including solar PV, wind, and hydro contributed 32%.

Data courtesy of Energy.gov.au

More Australians have rooftop solar than swimming pools

It’s safe to say that Australians love solar; Queenslanders are leading the global charge with the most uptake in rooftop solar systems, with a record-breaking 1 million installations milestone reached in early 2024. That’s more solar installations than anywhere else in the world.

In 2022, renewable energy sources accounted for 32% of Australia’s total electricity generation, with solar contributing 14% of that pie (Energy.gov.au). This figure is rapidly growing year on year and has even recently overtaken the number of swimming pools in Australian backyards. 

Data courtesy of Australian PV Institute

How does nuclear fit into Australia's energy mix?

Adding nuclear to Australia’s energy mix would have some interesting effects on our energy landscape. For one, nuclear technology as of 2024 can only operate at full capacity 24 hours a day, leaving little room for other energy sources to contribute. It is a highly stable, highly inflexible energy source that could sustain Australia’s electricity demand while likely making other fuel sources redundant. There are a few good reasons why this may actually result in a fragile system for Australia, but more on that soon. 

Second, nuclear is currently being discussed because of the Coalition’s plan to introduce nuclear to Australia’s energy mix should they win the 2025 federal election. If this were to occur, it is pretty obvious that the Coalition also plans to halt all current renewable energy development (particularly large-scale solar PV and wind) in favour of keeping coal and gas plants running. These fossil fuel plants would continue to run until the Coalition can fund the seven SMRs and large-scale nuclear plants into development. 

This plan, unfortunately, is detrimental to Australia’s Net Zero targets and directly misaligns with the 2015 Paris Agreement. It also doesn’t present a solution for the millions of Australians with rooftop solar installed on their homes - if nuclear is introduced, what does it mean for those investments? Nuclear is inflexible and can’t easily be ramped up and down like traditional coal-fired or gas plants - will introducing nuclear energy make rooftop solar redundant?

"Will introducing nuclear energy make rooftop solar redundant?"

Nuclear and solar energy coupling is debated

A large problem that nuclear energy poses is its inability to play nicely with other energy sources. Nuclear power plants (both SMRs and large-scale plants) are extremely expensive. For these plants to be economically viable, they must operate at maximum capacity all day, every day, all year round. 

This causes an issue for solar and any other electricity source, simply because nuclear leaves little room for others to generate electricity. It would alter the existing dynamic between solar and the grid network, where excess solar energy from rooftops can be exported to the grid and where large-scale solar PV backs up the grid during the day.

Dr Robert Barr, a Nuclear for Climate lobby group member, states that it is inevitable that nuclear and solar will clash and yes, this is a problem that will need to be solved given the increasing importance renewables play in Australia’s energy landscape. Barr believes that this clash could be managed if solar self-consumption is encouraged and incentivised to reduce solar export, and if new nuclear reactor technologies are introduced to allow nuclear to ramp up and down as a flexible baseload. 

Flexible reactor technology is not currently implemented anywhere in the world and remains an unproven tech - NuScale, a developer of SMRs in the USA, claims that their SMR technology can be integrated with renewables and act as a baseload, backing up renewable sources “through flexible operation or load following - adjusting production as electricity demand fluctuates” (IAEA). NuScale were pioneering this technology in Utah’s CFFP project but it never came to pass as the project fell through in 2023 due to exorbitant budget blowouts. So, we’re still waiting to see whether cooperation between nuclear and solar energy is achievable. 

A rendering of NuScale's SMR nuclear power plant planned for construction at Idaho National Laboratory. Image courtesy of NuScale Power.

That being said, nuclear energy as of 2024 is inflexible and would push out solar generation from Australia’s energy mix. According to ABC News, Dr Barr is adamant that the best case scenario, given current nuclear energy technology, would be for solar panel owners to simply turn off their solar for the “greater good”. This might be a tough pill to swallow for the millions of Aussies who have invested in rooftop solar to achieve lower bills and energy independence. 

Solar panel owners should turn off their rooftop solar for the "greater good"... 

This might be a tough pill to swallow for those who have invested thousands into their personal solar energy systems.

Toby Couture, director of Berlin’s independent think tank, E3 Analytics, agrees that at this stage, nuclear causes more issues than helps (Hockenos). Couture states, “Nuclear is inherently inflexible, and to accommodate the variability of wind and solar output, what we ultimately need is both flexible sources of supply, and greater flexibility of demand. The presence of nuclear actively hinders both.”

Nuclear and renewables are at odds because of nuclear's inflexible nature and because renewables (like solar and wind) want to operate as much as possible when conditions allow as it’s the cheapest source on the market with the lowest marginal cost of operation. So, both solar and nuclear are trying to push the other out for maximum generation. 

Inflexibility in the energy mix causes issues and limits effectiveness, as seen with France’s energy crisis in recent years. Couture describes France’s nuclear landscape as brittle - its nuclear power system is so inflexible that solar and wind are unable to be integrated effectively because they can’t ramp down the nuclear to make room for renewables. As France’s nuclear power plants age, the reactors are vulnerable to interruptions such as maintenance or even natural disasters. If France can’t interject a secondary source to stabilise the grid in times when the reactors are vulnerable, then the country is set to buckle in for more energy crises on its hands.

Nuclear power plant in Golfech, France.

Electricity bills would increase in a nuclear Australia

Unless flexible nuclear technology is implemented to cooperate with renewables such as solar PV, Australians would find their electricity bills skyrocket in a nuclear Australia. 

Solar PV and wind energy generation positively impact wholesale electricity prices in Australia. The Australian Energy Market Operator (AEMO) Executive General Manager Reform Delivery, Violette Mouchaileh, stated last year that, “Record renewable energy generation output helped push down average wholesale electricity prices by more than two-thirds, double the occurrence of zero or negative wholesale prices (19%) and reduce total emissions by 11% compared to the previous September (2022) quarter”. 

Renewables actively reduce wholesale electricity prices, which in turn is lowering the average Australian’s electricity bill. 

Renewables push down wholesale electricity prices and electricity bills.

Solar PV and other renewables are also the cheapest of all energy generation technologies to build and maintain long-term, even when accounting for transmission and storage costs. The GenCost 2023-24 report delivered by CSIRO and AEMO estimated that large-scale PV solar costs $2,800/kW, or $100/MWh.

Solar PV farm.

In comparison, SMRs would cost Australia around $28,600/kW in upfront capital. This is a staggering figure, and according to the GenCost report, would continue to cost Australia an estimated $230 - $382/MWh. 

To estimate the effect nuclear would have on Australian electricity bills, extensive modelling scenarios need to be run by AEMO. This hasn’t happened yet, but Monash University recently made some broad assumptions based on the “levelised cost of electricity” (Dargaville). This calculation was actually based on the uptake of large-scale nuclear, which is more cost-effective than SMRs, with development costs approximately $8,655/kW or between $155 - $252/MWh. 

Dr Roger Dargaville, the Deputy Director of the Monash Energy Institute and associate professor, estimates that with large-scale nuclear, electricity tariffs could rise from 25-30 cents/kWh to 40-50 cents/kWh. This is a significant increase in the average Australian electricity bill and demonstrates that nuclear is unlikely to be competitive. And this is for the cheaper of the nuclear options. It’s easy to imagine how much more electricity bills may increase with SMRs.

Large-scale nuclear plants and SMRs would significantly increase wholesale electricity rates, which would be passed on to the consumer.

Australia's carbon emissions would worsen with nuclear

Yes, once constructed, nuclear power plants generate carbon-neutral energy. However, in the 15+ years it takes to build SMRs and large-scale nuclear plants, Australia’s climate emissions would blow out by a staggering 2.3 billion tonnes between now and 2050. 

These estimations are based on comparisons with the AEMO's Integrated System Plan 'Step Change Scenario', which models the most likely energy transformation under current policy settings and includes the ongoing rollout of large-scale renewable projects. 

Data courtesy of Solutions for Climate Australia

With the Coalition’s plan to halt the development of renewables in favour of keeping coal-fired and gas plants open while nuclear reactors are constructed, Australia would not meet the following targets:

• Reduce Australia's emissions by 43% by 2030
• Achieve net zero emissions by 2050

Elly Baxter, a Senior Campaigner at Solutions for Climate Australia, states, “This analysis demonstrates that nuclear reactors in Australia would contribute to worse climate outcomes. Nuclear is a worrying distraction from getting on with the urgent job at hand: replacing polluting coal and gas with the sun and wind technology we have right now”.

Solar PV technology is available, is comparatively quicker to construct, and keeps Australia on track to meet our emissions targets. The Coalition’s plan for nuclear counteracts these targets and would lead Australia down a road that is very likely to see our shortcomings presented on a global stage when we’re unable to honour our 2015 Paris Agreement commitments.

Solar PV pros and cons

Solar energy is a variable energy source that is heavily dependent on the availability of the sun. Its intermittent nature presents challenges as it is vulnerable to underperforming. As a result, solar needs a reliable backup power source like large-scale battery storage (which isn’t currently available), or possibly paired with nuclear for baseload energy (if flexible nuclear technology is achieved). Solar-rated capacity (20-40%) is low compared to other energy sources currently available, such as coal-fired generation (60%) and nuclear reactors (92.5%). 

However, solar PV technology is available now, quick to build, and requires very low capital and maintenance costs compared to other energy sources. Solar PV, along with other renewable technologies, is also highly reliable when weather permits, and is already generating a significant portion of Australia’s energy demands. Solar is helping to fast-track Australia to meet our net zero emissions targets while remaining low-cost. Solar is also keeping Australian electricity bills lower as the amount of solar energy exported to the grid directly influences wholesale electricity prices. 

Commercial solar installation by Springers Solar.

Also, when large-scale storage technology becomes available for implementation, the good news is that storage capacity does not need to be met on a kW to kW basis with solar. This is because storage only needs to meet the maximum demand, which is significantly lower than the capacity of variable renewables. This is largely due to being able to utilise existing electricity systems, and peaking events don’t necessarily align with critical backup generation times. 

Solar PV’s flexibility, reliability, cost-effectiveness, and availability make the continued development of solar farms and rooftop solar extremely attractive for Australia. 

Nuclear pros and cons

In comparison, nuclear presents a highly reliable but highly inflexible energy source. Nuclear power plants can generate enough carbon-free electricity to keep Australia powered long-term with a nuclear reactor’s ability to operate at 92.5% capacity, 24/7.

However, the introduction of nuclear in Australia comes with many caveats. Nuclear SMRs and large-scale nuclear plants are horrendously expensive in both capital cost and operational costs. These costs would trickle down to Australian electricity bills, where we would see a noticeable increase in our average bill. Nuclear power plants are estimated by the CSIRO to be 50% more expensive than wind, solar, and batteries combined. 

In addition, the failed CFFP project in Utah provided valuable data regarding pipeline development, where we can now conclude that an SMR or large-scale nuclear plant would take 15+ years to build from pre-construction to operational. This means that nuclear would not be feasible to implement before the deadline for ending coal-fired power in line with national emissions targets. “Due to the current state of the development pipeline in Australia, the earliest deployment [of large-scale nuclear plants] would be from 2040,” states the CSIRO and AEMO.

Nuclear is also inflexible and can’t easily be ramped up and down to accommodate other energy sources, such as renewables. This causes a large pain point given Australia’s adoption of solar PV (both large-scale and rooftop solar) and it weakens Australia’s energy mix. France is an example of how putting all your eggs in one basket can result in a frail system.

If flexible nuclear technology is introduced, perhaps then we could argue that solar and nuclear can cooperate to create a strong, carbon-neutral energy mix. 

But for now, a nuclear Australia seems like a pipe dream, whereas solar provides a real, achievable solution to a problem that is already on our doorstep demanding action.

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