Renewables have won the generation race — but not yet the reliability one.
Across Europe, record amounts of wind and solar power are now online. In the UK, renewables supplied almost half of all electricity in 2024. Yet emissions from power generation barely fell. Why? Because clean energy still collides with an old system built for fossil fuels.
When wind output soars, the grid can’t always use it — so turbines are switched off. When it drops, gas plants fill the gap. The result is wasted potential, higher costs, and slower progress towards net zero.
The challenge isn’t how to make more renewable energy. It’s how to make it work — everywhere, all the time.
As National Grid ESO puts it, “a renewable-dominated grid requires flexibility, digitalisation and coordination across every level of the system.”
Here are five areas where that transformation is already underway — and what still needs to happen to make the key renewable energy challenges disappear.
1. Storage that’s diverse, not just large
Energy storage is what keeps a renewable grid reliable. It saves excess electricity from windy or sunny periods and releases it when output falls.
- The UK currently has around 7 GW of operational battery-storage projects (DESNZ Renewable Energy Planning Database, 2025).
- ESO’s Future Energy Scenarios 2024 projects at least 30 GW will be needed by 2035.
But scale alone won’t cut it.
- Lithium-ion batteries handle second-by-second balancing.
- Pumped hydro and hydrogen provide multi-day storage.
- Thermal systems store heat directly, easing pressure on the grid.
The future mix must combine all three. Costs have fallen by more than 80 % in the past decade, but supply-chain limits, grid-connection queues, and capital costs still slow deployment. Storage is crucial — but it only works if the grid can use it intelligently.
2. Grids built for intelligence, not inertia
Much of the UK’s network dates back to the 1950s–70s. About 60% of high-voltage assets are beyond their design life (ESO Asset Health Review 2023). Adding renewables to that infrastructure is like adding faster trains to outdated tracks.
The Pathway to 2030 programme lays out £54 billion in upgrades to make the grid:
- Smarter – sensors and data analytics for real-time control.
- More connected – power routed where it’s needed most.
- More dynamic – automatic re-dispatch when faults occur.
Another bottleneck is bureaucracy: more than 400 GW of projects are waiting to connect — several times current UK demand. Digitalisation, automated approvals and regional coordination must all accelerate if new capacity is to reach the market fast enough.
Storage buys time; a smarter grid makes that time useful.
3. Forecasting that turns volatility into foresight
Renewables are only as dependable as our ability to predict them. Short-term forecasting errors for wind generation still average 10–15% globally (IEA Renewables 2024). In the UK, every 10 % forecasting miss in winter can add £50 million to balancing costs (ESO Balancing Report 2023).
Better forecasting isn’t just about weather models — it’s about merging them with live grid data. The UK Met Office and Energy Data Hub are testing joint analytics that have already cut balancing costs by up to 8%.
With more accurate, shared data, operators can anticipate surpluses or shortages hours in advance — avoiding expensive last-minute interventions and keeping the grid stable even when nature isn’t.
Forecasting precision is the difference between reacting to volatility and managing it.
4. Flexibility that scales automatically
Storage smooths supply. Flexibility manages demand — and that’s the piece most grids still lack.
Demand-side flexibility allows small, temporary reductions in electricity use when the grid is under stress. Instead of firing up gas turbines, operators can momentarily reduce heating or cooling loads across thousands of sites.
The UK’s Demand Flexibility Service proved the model:
- 1.6 million households took part in 2023–24.
- They cut peak demand by 3.3 GWh, according to the DFS Review 2024.
Manual participation, however, only works for so long. Real flexibility must be automated — consistent, invisible, and built into daily life.
That’s already happening through aggregators such as Voltalis. By connecting homes and businesses into a virtual power plant, Voltalis adjusts connected electric-heating systems by just a few degrees during peak periods — delivering flexibility in seconds, without any discomfort or effort from users.
Across Europe, more than 250 000 sites and 1.5 million devices are already participating. The IEA Demand-Side Flexibility Report 2023 estimates this kind of automation could cut system costs by $270 billion annually and avoid 500 Mt CO₂ by 2030.
Flexibility turns passive consumers into active assets — and demand into a tool for stability.
5. Systems that work across sectors
Electricity doesn’t exist in isolation. The next leap forward will come from connecting power, heat and transport.
- Electric vehicles (EVs), through vehicle-to-grid (V2G), can discharge power back to the grid during peaks.
- Heat pumps can pre-heat homes when renewable output is high, then ease off when demand spikes.
- Smart home systems can coordinate appliances, charging and heating automatically.
According to ESO’s Future Energy Scenarios 2024:
- V2G could deliver up to 25 GW of flexible capacity by 2030.
- Electrified heat could add another 7 GW by 2035.
Cross-sector coordination will multiply flexibility across millions of endpoints — homes, offices, cars — turning the whole energy ecosystem into a responsive network.
From intermittent to intelligent: understanding the key renewable energy challenges
The challenge with renewables isn’t the weather. It’s the system’s rigidity.
Our grids were built for predictable, centralised power. Now they must adapt to distributed, variable, digital generation. Every innovation — from storage and smarter grids to forecasting and flexibility — serves one goal: making clean energy reliable.
- Storage buys time.
- Smarter grids use it efficiently.
- Forecasting anticipates change.
- Flexibility bridges the rest.
Together, they turn intermittency into intelligence.
If storage is the battery of the future, flexibility is the brain.
Voltalis is already showing how that brain works — an invisible layer of coordination that keeps costs down, emissions low and comfort exactly where it should be.
The energy transition isn’t just about generating clean power; it’s about orchestrating it. The winners won’t be those who produce the most electricity, but those who manage it best.
