Ready for the next blackout? Why battery storage is important.

What happens when the power grid fails?

Imagine you are having lunch on a regular Monday, and suddenly the world around you comes to a standstill. The lights flicker, screens go dark, traffic grinds to a halt, and the hum of modern life falls silent. This was not a scene from a movie, but reality for millions of people in Spain and Portugal on April 28, 2025.¹ In one of the most severe power outages to hit Europe in recent history, the Iberian Peninsula was plunged into darkness, disrupting businesses, hospitals, communication networks, and daily operations on a large scale.¹ This widespread blackout brought to light critical vulnerabilities. 

Events like this starkly remind us how dependent we are on a complex, interconnected, and sometimes vulnerable power grid. They expose the weaknesses of the systems that drive our modern lives. While grid operators are working diligently, the blackout on the Iberian Peninsula underscores the growing desire of people for more control over their energy supply – a pursuit of personal energy resilience and independence, particularly in the case of an unexpected power outage.

This incident raises critical questions about grid stability. This analysis will explore the events during the Iberian blackout, investigate possible causes, and highlight how home battery storage solutions offer homeowners a powerful way to secure their emergency power supply, gain independence from grid uncertainties, and contribute to a more sustainable energy future. Solutions like those from Modual provide a tangible solution for power outages to achieve this security and peace of mind.

Anatomy of a blackout: What exactly happened in Spain and Portugal?

The blackout occurred with alarming speed. Around 12:30 PM local time (CEST) on Monday, April 28, 2025, there was a significant disturbance in the Iberian Peninsula's power grid.¹ The event primarily affected mainland Spain and Portugal, where nearly 60 million people reside.² Short-term impacts were also felt elsewhere, illustrating the interconnectedness of the European power grid.³

The scale of the outage was unprecedented. The Spanish grid operator Red Eléctrica de España (REE) reported a catastrophic loss of 15 gigawatts (GW) – about 60% of the demand – in just five seconds.¹ Together with Portugal, the total shutdown reached approximately 20 GW.⁸ This nearly instant collapse, referred to as "el cero" (the zero), represented a complete system failure.⁹

Maintaining grid stability requires perfect synchronization of generation and demand.¹ On that day, this balance was violently disrupted. The extreme speed and magnitude suggest a vulnerable system prone to cascading failures. It is likely that standard protective devices were either overwhelmed or bypassed, possibly due to underlying instability factors such as low system inertia or the behavior of the generation mix, triggering a domino effect.¹

What were the far-reaching consequences?

The consequences were immediate and far-reaching. Modern life came practically to a standstill:

1. Transportation: Subways and trains stood still, traffic lights went out, airports experienced delays.¹

2. Communication: Mobile and internet services faltered.¹

3. Commerce: Stores closed, ATMs stopped, electronic payments failed.²

4. Healthcare: Hospitals relied on emergency power (generators) and suspended routine operations.¹

5. Public response: Scrambles for essentials like water, food, batteries, flashlights.²

6. Tragic outcomes: At least eight deaths related to the blackout (fires, generator issues).⁵

How long did the recovery take?

Restoring power was complex. REE initially estimated 6-10 hours.⁵ While some regions recovered faster⁴, full normalization of the grid took nearly 23 hours.¹³ Portugal confirmed stabilization late on Tuesday.⁴ Satellite images showed ongoing darkness early on the morning of April 29.¹³

This extended recovery indicates difficulties in executing a "black start" – restarting the grid from scratch. This requires specialized resources and careful coordination.¹⁵ The extended timeline poses challenges and underscores the need for robust black start capacities and grid resilience planning, especially reliable backup power sources.

Why did the blackout happen? Unraveling the complex causes

Identifying the exact trigger proved challenging. Diagnosing faults in large, interconnected systems is inherently complex.¹ Authorities warned against speculation as the cause is still under investigation.¹

What is known is that the grid was previously unstable. Sensors detected voltage fluctuations hours before the collapse.¹ REE confirmed two “separation events”; the first was withstood by the system, but the second resulted in the catastrophic collapse and disconnection from the larger European grid.¹ This points to a cascading failure.¹

There are several potential contributing factors:

1. Geographical origin & initial theory: The origin is believed to be in the Spanish region of Extremadura (high concentration of power generation, including solar plants).⁸ An initial REE theory pointed to two solar plants⁹, but this was later deemed premature.⁹

2. The "atmospheric disturbance" confusion: Initial reports cited a “rare atmospheric phenomenon” affecting power lines.³ This was later denied by the Portuguese operator REN⁸, and the Spanish weather agency reported no unusual conditions.³ This confusion highlights the difficulty in diagnosing complex failures quickly.

3. Speculation about a cyberattack: Given the scale, cyber-sabotage was considered.⁸ Spanish courts investigated²¹, but grid operators and experts found no early evidence of intrusion.²

4. The role of renewable integration: A debate arose over the impact of high solar penetration (solar power was supplying a significant amount of electricity before the collapse).⁸ While official sources denied an “excess of renewable energy”²², the event highlighted the challenges of managing grid stability with many inverter-based resources (IBRs) like solar/wind, which have different properties (lower inertia) compared to conventional generators.¹⁶ The rapid collapse¹ near large solar plants⁸ suggests the issue is more about adapting grid architecture and control to a changing energy mix rather than renewable technology itself.

What can we learn about grid vulnerability and resilience?

The blackout on the Iberian Peninsula dramatically highlighted society's dependence on stable, centralized electricity supply.¹ The chaos underscored the impact of losing this critical infrastructure and emphasized the need for reliable solutions for power outages.

The event uncovered potential vulnerabilities:²⁶

1. Limits of interconnection: The limited connection of the Iberian Peninsula to the rest of Europe (“energy island”) hinders support in crises and resource sharing.²² Calls for strengthening these connections have intensified.²²

2. System redundancy: The importance of robust safety measures was highlighted.²²

3. Need for modernization: Urgent need for advanced monitoring, increased grid flexibility (smart technology, demand response, storage), and reliable backup power options.²²

Perhaps most revealing was the public reaction: an astounding 450% surge in demand for solar batteries and hybrid systems. This indicates that consumers are actively seeking personal solutions for energy security and independence in the face of grid fragility. Such disruptions are a catalyst for change and create momentum for investment in strengthening grids, operational processes, and flexible assets like energy storage.²², ²⁶, ²⁷

How can home battery storage provide security during a blackout?

While improvements to the power grid are essential, the blackout demonstrated the immediate value of battery storage for homeowners seeking to maintain control. These systems function like an energy bank, storing electricity (from the grid or solar panels) for later use.²⁸ They are a crucial solution for power outages.

Why home battery storage?

1. Reliable emergency power: Provides continuous, automatic emergency power during outages, switching almost instantaneously unlike generators.²⁸, ³⁰ Paired with solar, the system can recharge using sunlight, potentially providing power for days during a prolonged blackout.²⁸ This is central to a reliable emergency power supply.

2. Greater energy independence: Store excess solar energy for later use, reduce reliance on utilities, and maximize “self-consumption.”

3. Smart energy management and cost savings: To minimize electricity bills, especially with time-of-use tariffs, charge devices when power is cheap and discharge when expensive (load shifting). This practice is currently less relevant in Switzerland due to minimal time-of-use tariff differences.²⁸, ³⁵

4. Environmental benefits: Enables greater use of clean solar energy, reducing household carbon footprint.³²

Home batteries empower homeowners to become active energy managers and maintain control over emergency power supply security, costs, energy sources, and environmental impact.

Why choose Modual for smart, sustainable energy independence?

Modual offers a compelling approach based on Swiss engineering quality, precision, and reliability.⁴⁵ Modual systems were designed to meet the needs highlighted by events like the Iberian Peninsula blackout, providing homeowners with a path to energy security and a reliable emergency power supply.

What makes Modual special?

1. Modularity & scalability: Systems like Series Basic AC/DC are modular.⁴⁵ Start with the capacity you need and expand later (up to 46 kWh for households) as needs grow (e.g., EV).⁴⁵ Address the challenge of predicting future needs.⁴⁰

2. Backup power: Designed for reliable emergency power supply during grid failures to keep essential devices running.⁴⁵ A vital solution for power outages.

3. Easy installation: AC-coupled systems offer easy plug-and-play installation; DC-coupled systems are compatible with many solar inverters.⁴⁵ Reduces installation complexity and costs.⁴⁶

4. The sustainability advantage: second-life batteries: Modual innovatively utilizes used EV batteries.⁴⁵ Reusing batteries provides:

5. Environmental benefit: Extends resource lifespan, promotes circular economy, reduces manufacturing footprint.⁴⁵

6. Potential cost efficiency: Can make storage more accessible.⁴⁵

This unique value proposition – reliable storage alongside sustainability – positions Modual as a forward-thinking player.³⁴ Modual offers a robust, intelligent solution to ensure vital energy independence and security against blackouts.⁴⁵

How do I choose the right home battery system for my needs?

Investing in a home battery requires understanding the technical specifications to suit your specific situation.⁴⁶ It’s about balancing performance, compatibility, durability, safety, and budget when selecting a solution for power outages.⁴⁶

Here’s what homeowners need to know:

What are my energy needs?

• Power consumption: Check bills for average daily kWh usage.⁴⁰ Identify power-hungry appliances.

• Backup goals: Essential loads or whole-home emergency power? How long should it provide power during a blackout (hours/days)?⁴⁰ (average Swiss household needs ~12 kWh/day).⁵⁰

• Future plans: Consider buying an electric vehicle or electric heating, etc.⁴¹

• Solar kWp estimate: A helpful method to estimate energy needs is to calculate kWp (kilowatt peak) and multiply by 1.2. This gives a general idea of the daily energy production potential.

What is the difference between capacity (kWh) and power (kW)?

• Capacity (kWh): How much energy is stored; determines charging capacity (typically 5-15+ kWh).⁴⁰, ⁴⁹

• Power (kW): How quickly energy is delivered; determines simultaneous device usage.⁴⁶ Check continuous and peak power.⁴⁷

How long does the battery last and what is the warranty?

• Expected lifespan: Usually 10+ years or cycles (In LFP often 5000+ cycles).⁴⁰, ⁴¹, ⁵⁰

• Warranty: Look for 10+ years, cycle/throughput limits, guaranteed residual capacity (e.g., 70%).⁴⁴

How efficient is the battery, and how much can I use (DoD)?

• Round-trip efficiency: Usable energy when discharging compared to charging (>85% typical).⁴¹

• Depth of discharge (DoD): Usable portion of capacity (80-100% for lithium).⁴⁰

Is the battery compatible with my system? (AC vs. DC coupling)

• Inverter compatibility: Ensure the battery works with your solar inverter⁴⁶.

• AC vs. DC coupling: AC (retrofit easier) vs. DC (new installation often more efficient).⁴⁷ Modual offers both.⁴

• Can I expand the system later? (Modularity)

• Consider if needs might grow; modular systems offer flexibility.

What are the installation requirements?

• Check indoor/outdoor suitability (IP rating), temperature tolerance, mounting, space/ventilation requirements.⁴⁷, ⁵², ⁴⁶ Professional installation required.⁴
  
  

What are the actual costs and the value?

• Upfront costs: Hardware + installation (typically CHF15k-25k+ before incentives).³⁹ Compare cost/kWh.⁵⁰

• Incentives: Search for government, cantonal, and utility programs.⁴⁶

• Long-term value: Total costs (upfront – incentives + savings + backup value). Consider chemistry (LFP vs. NMC).²⁸

Table: Key questions when choosing your home battery storage system

It is highly advisable to consult qualified installers for personalized advice on the best solution for power outages.

Are you ready to secure your energy future against blackouts?

The Iberian Peninsula blackout is a clear warning: Dependence on the power grid carries risks. Major disruptions impact lives and communities. Energy preparedness and resilience are increasingly important.

For homeowners, battery storage is a powerful solution for power outages. It provides more than just backup power; it enables energy independence, control over usage, reduced reliance on utilities, potential cost savings, and supports a clean energy ecosystem.

Modual offers solutions that are smart, reliable (Swiss-engineered), and uniquely sustainable with modular designs and second-life EV batteries – a robust emergency power supply option.

Taking control of your energy future is easy. Understand your needs, explore modern battery storage, and enhance your home’s resilience against outages and blackouts.

Are you ready to protect your home before the next blackout? Examine your energy usage and discover how Modual solutions can provide security and peace of mind. Visit modual.ch or contact a Modual representative for a consultation to learn more about securing your energy future.

Sources:

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² What we know about Monday’s sweeping power outage in Spain and Portugal. AP News. https://www.apnews.com

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⁴ It will take ‘many days’ to find out causes of Iberia blackout. The Brussels Times. https://www.brusselstimes.com

⁵ Home Energy Independence: Why You Need a Battery. GoodLeap. https://www.goodleap.com

⁶ Power outage triggers surge in storage and backup system enquiries. Strategic Energy. https://strategicenergy.eu

⁷ Home Batteries: Unlocking Energy Independence for Homeowners Without Solar. Soligent. https://www.soligent.net

⁸ Iberian blackout: Cyberattack is not to blame – but the threat to power grids is real. weforum.org. https://www.weforum.org

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²³ 5 Benefits of a Home Battery. Enact Systems. https://enact.solar

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³¹ Complete Guide to Battery Backup. Green Ridge Solar. https://www.greenridgesolar.com

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³³ How A Home Battery Backup System Can Help You. FranklinWH. https://www.franklinwh.com

³⁴ Your Guide to Home Backup Batteries in 2025. EnergySage. https://www.energysage.com

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⁴¹ Round-trip measurements. Modual R&D. https://www.modual.ch

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About Modual

Modual is the leading manufacturer of second-life battery solutions in Switzerland, dedicated to developing sustainable energy solutions through innovative battery technology. By repurposing cells from electric vehicles (EV), Modual offers high-performance, eco-friendly battery systems for a variety of applications. Our commitment to sustainability, coupled with our rapid growth and technological leadership, enables us to significantly reduce the environmental impact of energy storage. At Modual, we are passionately committed to a cleaner, greener future, one battery at a time.

Contact us now for a non-binding quote.