Energia
Solar Growth Demands a Smarter, More Resilient Power Grid
The Global Shift From Fossil Fuels to Solar Power Grids
In the aftermath of the power grid collapse in the Iberian Peninsula (Portugal and Spain), many questioned the root cause of what happened. And, like many things today, the discussion quickly became politicized, with solar power accused of being the reason for the crash.
Source: RNZ
And it might be partially true, at least to some extent. The power grid was designed decades ago, with a centralized, fossil-fuel-centric design built around a few massive power plants able to generate power on demand.
In comparison, a decentralized and renewable energy supply functions in many different ways. As solar power gets cheaper, it will likely take over more and more of total energy generation. Currently, solar represents 80% of new power generation added to the grid, and wind another 10%.
With 585 GW of capacity additions, renewables accounted for over 90% of total power expansion globally in 2024.
Solar and wind energy continued to expand the most, jointly accounting for 96.6% of all net renewable additions in 2024. Over three-quarters of the capacity expansion was in solar energy which increased by 32.2%, reaching 1 865 GW, followed by wind energy which grew by 11.1%.
Source: Irena
So while a green, renewable-based power supply seems imminent, making the power grid able to handle it will be vital. Especially as any power grid failure like the recent one, if it was really caused by solar energy supply, will slow down solar energy adoption and indirectly cause carbon emissions to stay high for longer.
How Electrical Power Grids Work and Why They Fail
A key element to understand about the importance of the power grid and the difficulties in keeping it running is that electricity is very hard to store.
In theory, this is what batteries are doing, but the power grid of a country is running power levels several orders of magnitude over what even the largest battery facilities can store.
So for now, power has to be produced in exactly the same quantity as it is consumed, in real time.
To add to this difficult task, power also needs to be delivered to the right place and at the right time. For example, solar power generated in Nevada will not help the Kansas grid if it is not connected to it with enough power lines it. In the case of Spain, the interconnections with the French power grid system were not large enough to save it from its localized problems.
Source: ResearchGate
Finally, changes in voltage need to be made. Long transmission of power can only be done efficiently at high voltage, requiring transformers to step up the voltage before pushing the electricity into the power lines. Consumption needs to be done at a lower voltage, which is also done with transformers.
Source: EIA
Spain Power Grid Failure: What Went Wrong?
Frequency Troubles
While it is likely that the Iberian grid collapse root causes will be hotly debated, potentially for months and years to come, we have a few data points that can partly indicate what happened.
The first is that the actual failure point was not about excessive or insufficient power generation, but the electric frequency of the power grid.
Utility frequency is a technical characteristic of the grid, determined by the oscillation of alternating current.
Source: Wikipedia
Different power grids have different standard frequencies, making them incompatible with each other. For example, the Baltic states have only recently switched to the European frequency, after decades of keeping the frequency inherited from the USSR.
If frequency goes too far out of standards, it can literally destroy transformers and other high-power equipment, as well as devices of regular users. There are numerous built-in mechanisms in electric power devices to automatically disconnect if the frequency fluctuates excessively.
Did Solar Power Cause the Spanish Grid Failure?
The grid frequency used to be generated and stabilized by the physical rotation of massive generators, usually powered by fossil fuels, but also hydropower and nuclear plants. This gave the grid a lot of inertia, making it very hard for the frequency to deviate much from the intended levels. However, solar power does not generate such inertia.
Source: SmartGrid
So it is not so much that solar power generation created the crash, but that its lack of inertia did not help stabilize the grid frequency, which was a key factor in the crash.
Still, it does not explain why the frequency fluctuated in the first place. In addition to a lack of inertia, which can be linked to solar power, it seems that some bad practices and old designs also contributed to the Iberian grid crash by making it vulnerable to what the grid operator described as an “extremely rare weather phenomenon”.
Upgrading Power Grids for a Renewable Energy Future
As older designs of transformers, power lines, and other infrastructure are the most common cause of outages, it makes sense that the first step to improve the power grid is to upgrade the equipment.
One step forward is the so-called smart grids, which monitor much closer what is happening at every level of the power grid in real-time, instead of a more general analysis. This also includes plenty of individual automatic systems.
This way, a fluctuation in the frequency localized in one specific area, due to a weather event, for example, could be isolated from the rest of the grid immediately before it spreads the problem any further.
Improvements to the power lines can also help. A denser power network allows for rerouting power from one region to another and reduces the sensitivity to a single failure point. Better insulation or burying power lines can also protect them against storms, snow & frost, wildfire, etc.
More connections between distant regions can also help average fluctuations in power generation from one sunny area to another. This generally requires dedicated infrastructure for ultra-long distance power transportation, something that China is the global leader in, with its “super grid” using ultrahigh-voltage (UHV) AC and DC power lines, with already 30,000 km of UHV lines (18,600 miles).
Source: IEEE
It is likely that similar transcontinental connections will need to be built in Europe and North America as well, for example, between Spain and North Europe, or East and West of the USA, with many independent grids not so connected yet.
In that respect, it is likely not an accident that the worst grid failure of the past years occurred in Texas and Spain, both relatively small and isolated grids.
Source: ASME
Finally, as electrification becomes the dominant trend in transportation, heating, and industrial processes, more power transmission capacity is needed overall to handle the growing demand moving away from coal, oil, and gas. This does not require a change in design or new technology, but more investment to build more power lines.
Grid Frequency Stabilization in Renewable Energy Systems
Battery Storage and Virtual Inertia in Power Grids
While smart grids are part of the answer, they are mostly going to reduce exposure to environmental effects and contain failures in smaller, more manageable areas than a country-wide crash.
To avoid crashes in the first place, especially as inertia-less solar power becomes the primary source of electricity, other solutions are needed.
Large-Scale Battery Storage (LSBS) could provide some help. These batteries are, anyway, going to be needed for a mostly renewable-based energy system, as solar panels are not producing energy in the evening at peak consumption time.
They can also provide frequency inertia, although in a different way than traditional large spinning generators. Inertia from batteries is called virtual inertia, or synthetic, simulated, or digital inertia.
When disturbances outside the normal frequency are detected, FFR pushes the grid frequency back into its normal operating range by rapidly injecting or drawing power from the grid.
Virtual inertia can respond even quicker than traditional generators to instability in the frequency, in less than 2 seconds.
This is a service that was first offered commercially in 2022 by battery facilities built by Tesla (TSLA ).
The Big Battery is able to provide ~2,000 “megawatt seconds” (MWs) of an inertia equivalency to help keep the grid stable. It does so via Tesla’s Virtual Machine Mode service. It will be able to provide ~15% of South Australia’s inertia shortfall.
Can Solar Panels Help Stabilize Grid Frequency?
By themselves, solar panels do not provide inertia, as there is no physical spin and kinetic energy to create it. But they could be used in ways to provide support to the grid as well.
For example, solar projects have been traditionally designed and incentivized to maximize production at all times. But by maintaining some spare generation capability, they could provide it in case of a drop in frequency.
This is very easy to do technically and has more to do with how solar plants are compensated by utility companies and grid operators.
Smaller scale of energy storage at the solar plant level could be similarly used to absorb small spikes in power and a rise in frequency. The grid operator could dedicate a specific amount of generation to be stored and made available for immediate dispatch if the frequency drops.
The same method could be used with the inverters linked to the solar panels. A plant controller could theoretically override the inverter controls for a short time frame to arrest a frequency drop, “running it hot,” but below the level where physical damage would be caused to the inverters.
In that scenario, every solar panel inverter would act as a mini stabilizer, providing additional virtual inertia.
Restoring Grid Inertia With Mechanical Spinning Solutions
If inertia is needed, and traditionally provided by spinning hundreds of tons of metal at high speed, maybe the solution to too little inertia is doing just that.
