WHY MISSION-CRITICAL DATA CENTRES CAN’T RELY ON SOLAR ALONE

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Solar energy is an important part of data centre decarbonisation, but it cannot deliver the continuous, high-density power that mission-critical facilities require.

To ensure 24/7 reliability while meeting sustainability goals, data centres must adopt diversified energy strategies that combine renewables with resilient, always-on power sources and climate-resilient design.

Key Insights:

• Mission-critical data centres require continuous, predictable power with zero tolerance for downtime
• Solar reduces emissions and energy costs but is inherently intermittent and cannot meet round-the-clock demand alone
• Battery storage supports short-term stability but is impractical for long-duration, large-scale power needs
• Real-world energy strategies combine solar with other renewables, grid supply, backup systems, and firm baseload power
• Climate change is increasing pressure on cooling systems and grid reliability, making resilience a core design requirement
• Future-ready data centres are built with flexible, diversified power infrastructure to balance sustainability and reliability

Picture a new data centre coming to life on a greenfield site. Servers are stacked, cooling systems humming, and AI workloads pushing the limits of what the facility was designed for. On paper, everything seems under control - but the energy behind it tells a different story. What once required tens of megawatts now demands hundreds, and each GPU-heavy rack can draw over 100kW, producing intense, constant heat.

Solar energy can help offset part of the load during daylight hours, but it can’t provide the continuous, high-density power these facilities require. Grid connections are stretched, and securing enough capacity can take years - if it’s even available. Planning approvals take years, and operators are discovering that relying on the public grid alone can slow growth - or even block it entirely.

At RED, we understand how energy strategy shapes every decision: where a site can be built, how facilities expand, and how operational and environmental targets are met. In this article we explore why solar energy, while valuable, is not enough on its own for mission-critical data centres.

Mission-critical IT infrastructure cannot compromise on power

Here at RED, we call data centres mission-critical for a reason. We're describing infrastructure where even brief power disruptions can have immediate, severe consequences: financial systems halt, healthcare platforms go offline, supply chains break, and essential public services fail.

These facilities need power that is reliable, continuous, and predictable - not 99% uptime, but 100%. Systems must run without pause, which requires predictable power quality, resilience against both grid failures and environmental disruption, and backup systems capable of maintaining full operation through extended outages.

The challenge is that sustainability goals often conflict with this zero-tolerance approach to downtime. Renewable energy helps the environment, but its output can be unpredictable. Mission-critical operations can’t afford interruptions, so additional measures are needed to keep power stable. The key isn’t choosing between decarbonisation and reliability - it's designing energy-efficient data centres and critical IT infrastructure that achieves both.

Why solar energy is attractive to data centre operators

Solar energy for data centres is increasingly used to reduce carbon emissions and manage data centre energy consumption. Net-zero commitments, investor expectations, and regulatory requirements all push operators toward low-carbon power sources, and solar provides a visible, measurable way to reduce emissions.

The economics are appealing too. Once installed, solar delivers predictable, low-carbon electricity, helping operators manage long-term energy costs and reducing exposure to fuel price swings or carbon pricing. For facilities designed to operate for 30-40 years, that stability is crucial.

Solar also delivers practical benefits during peak daytime periods, when generation is highest. It can directly support operational loads, ease pressure and reduce dependence on local grids, and even make sites viable that would otherwise face costly or delayed grid connections.

Where land is available and planning permissions allow, on-site solar generation gives operators direct control over part of their energy supply. Where space is limited, off-site solutions, like power purchase agreements (PPAs), allow facilities to claim renewable energy benefits while keeping operations flexible.

The reality check: why solar alone doesn't meet mission-critical needs

Despite its benefits, solar energy cannot reliably power mission-critical data centres on its own. The main limitation is reliability: solar stops generating at night and fluctuates throughout the day based on weather conditions, cloud cover, and seasonal variation, while data centres operate continuously, without pause.

A data centre's power demand doesn't drop when the sun sets or clouds roll in, and a facility drawing 50MW needs that power continuously, predictably, and without interruption - something solar generation simply cannot guarantee.

In theory, a data centre could be run entirely on solar, but in practice it quickly becomes unrealistic. The sheer number of panels needed to generate enough power during peak hours (even a medium-sized facility would require anywhere between 10,000 - over 100,000 depending on power demand), combined with the hundreds of acres of land required to site them, makes this approach impractical at scale.

Even where space is available, generation rarely matches demand. Solar output peaks during the middle of the day, while data centre energy consumption remains high through the evening and overnight. Cooling systems, compute workloads, and supporting infrastructure continue running at full capacity even at night, meaning that, in real-world conditions, solar must be supported by other energy sources to ensure continuous, reliable operation.

Battery storage helps - but only within limits

Battery storage is often presented as the solution to solar variability, and it does play an important role. Storage systems can smooth short-term fluctuations, provide backup during brief outages, and shift surplus daytime generation into the evening as solar output falls.

For data centres, batteries are particularly valuable for managing grid instability, maintaining power quality, and bridging the gap during generator start-up. They’re a core part of any resilient power strategy.

However, batteries don’t address the challenge of sustained, long-duration power demand. Storage systems are effective for minutes to hours, not days or weeks; a data centre experiencing a multi-day grid outage, or operating through extended periods of low solar generation, cannot rely on batteries alone.

At data centre scale, storing enough energy to cover these scenarios would require vast capacity, significant space, and substantial investment, making it impractical with today’s technology.

Batteries complement solar generation, but data centres still require power supplies that deliver uninterrupted output, day and night, in all conditions.

Where solar fits in a real-world data centre energy strategy

In real-world data centre environments, solar is most effective as part of a broader, diversified energy strategy rather than as a standalone solution. How it is deployed, and what it is combined with, depends on site constraints, planning considerations, and the need to maintain continuous, reliable operation.

• On-site solar: Works where land and planning allow, integrated safely into the facility’s power systems. Supports daytime loads and reduces pressure on local grids, provided generation can be integrated into the wider power architecture without compromising resilience.
• Off-site solar (PPAs): Allows operators to support renewable generation without the physical constraints of on-site installation, while maintaining flexibility around site selection - but facilities remain tied to grid availability.
• Diversification reduces operational risk: Solar energy for data centres peaks during daytime hours, while wind often provides more consistent output overnight and through winter months. Combining complementary renewable sources helps smooth variability across seasons and operating conditions.
• Geography matters: Coastal locations may favour wind over solar, while inland sites may offer the reverse. Effective strategies respond to local conditions rather than applying a one-size-fits-all solution.
• Resilience remains the priority: Facilities designed around multiple energy sources, solar, wind, grid supply, and backup systems, reduce exposure to weather-driven variability and single points of failure.
  

The smartest energy strategies balance renewables with robust backup and grid support - ensuring data centres stay online while meeting long-term low-carbon goals. This is a principle RED applies in its designs, blending renewable integration, grid strategy, and backup systems to support resilient and sustainable data centre infrastructure.

How does climate change affect the built environment?

Climate change is already affecting the built environment, and data centres feel the impact acutely. Rising temperatures push cooling systems harder, extreme weather challenges grid stability, and prolonged heatwaves stress power systems beyond their limits.

For mission‑critical facilities, “shutting down” isn’t an option. Data centres must stay online through heatwaves, storms, flooding, and other climate-driven disruptions that are only becoming more frequent and severe.

That’s why climate adaptation has to be part of data centre design from day one. Site selection now includes climate risk assessment, infrastructure must be hardened against extreme weather, and power systems are engineered to maintain operations even if the grid falters. Even solar output can be affected by dust storms, extreme heat, and wildfires, so energy strategies must account for both today’s conditions and tomorrow’s risks.

Energy strategy and climate resilience go hand in hand: renewables help fight future climate risk, but climate change already impacts their reliability - today’s designs must tackle both.

Designing for the future of data centre infrastructure

As data centre technology evolves and AI compute infrastructure growth continues, power strategies need to keep pace. Facilities being designed today will operate for decades, supporting workloads and systems we can’t fully imagine yet.

This requires infrastructure built to adapt. Power systems need to accommodate higher densities, cooling systems must cope with rising heat loads, and energy strategies must balance sustainability commitments with round-the-clock reliability.

Solar will play a growing role in this future - but only as part of a broader system. Organisations building today's AI data centres are investing in diversified energy strategies that combine renewables with grid connections, on-site generation, and increasingly, dedicated baseload sources like nuclear to deliver the continuous, predictable power mission-critical operations demand.

The challenge isn't choosing between solar and other power sources - it's designing systems where each component works together to deliver both reliability and sustainability at scale.

Solar energy for data centres is essential - but resilience comes first

Solar energy for data centres is a valuable, increasingly essential component of decarbonisation. It cuts emissions, provides long-term cost stability, and demonstrates commitment to sustainability in ways that matter to investors, regulators, and the public.

But solar alone can’t power mission-critical operations. Its variability, the land and storage requirements needed to compensate for that variability, and the absolute requirement for constant uptime required mean that solar must be paired with reliable, always-on power sources.

Sustainability succeeds only when reliability is guaranteed. That’s why At RED, we help clients navigate these complexities. We’re experts at building infrastructure that balances environmental goals with the operational realities of mission-critical facilities, and we can help you design resilient, low-carbon data centres that deliver on both. Contact us today to future-proof your facilities.