Belgium's saturated electricity grid: the myth of all-electricity revealed

The myth of "all-electric" versus the reality of the Belgian grid

For several years now, the message has been hammered home by public authorities, the media and those involved in the energy transition: photovoltaic (PV) panels + heat pumps (HP) + electric vehicles (EV) = successful transition. On paper, the equation seems logical: we electrify our consumption and power it with decentralised renewable energy production.

In real life, this equation becomes fragile — even dangerous — as soon as we introduce two realities that no one wants to face:

• 📊 Networks have physical limitations (maximum current, voltage variations, transformers, cables sized for other uses)
• ❄️ "Newly electrified" uses (heating, mobility) consume energy mainly when PV produces the least: winter evenings, cold spells, short and grey days

In December 2025, ORES, Wallonia's main distribution network operator (DNO), sounded the alarm in an explosive internal document presented at its general meeting. The striking sentence that should be at the centre of public debate:

"The 'everything, everywhere, all the time and right now' model is no longer sustainable today." – ORES, December 2025

ORES identifies four simultaneous revolutions that are piling up on the same ageing infrastructure:

1. Decentralised renewable energy production (massive residential PV)
2. Decarbonisation of heating (electric heat pumps)
3. Electric mobility (vehicles and fast charging stations)
4. Electrification of industry (industrial processes, data centres)

The problem is therefore not "loving electricity" or "hating oil/gas". The problem is believing that we can electrify on a massive scale without managing demand, without storage, without flexibility, and without backup solutions.

Alarming figures from ORES: a network on its last legs

The official data published by ORES in December 2025 paints a stark picture of the critical state of the Walloon electricity grid:

At the same time, connection requests are skyrocketing at an unsustainable rate:

What the grid can (and can no longer) guarantee: physical limitations

Two fundamental constraints: thermal and voltage

ORES points out that all electricity grids have to deal with two types of unavoidable physical constraints:

For years, the focus has been on overvoltage (PV systems injecting too much locally, inverters shutting down in summer). Today, undervoltage is once again a major issue,as power demand is skyrocketing with the electrification of heating and mobility.

The low-voltage network was not designed for this scenario

ORES explicitly states that at the "feeder" level (low-voltage neighbourhood power supply), we now see the simultaneous occurrence of:

• ☀️ Overvoltage linked to residential photovoltaic installations (massive localised injection on sunny days)
• ⚡ Undervoltages linked to excessive consumption: fast charging stations and domestic heat pumps

And the figure is enormous: 10,000 out of 70,000 circuits are considered vulnerable to this double constraint. Low-voltage networks were historically designed for unidirectional consumption (power station → home), not to manage bidirectional injection + tenfold increases in consumption peaks.

"Low-voltage networks were initially designed for consumption. Electricity is now available locally and intermittently. Balancing the network comes at an increasing cost." – CWaPE, December 2025 presentation

Undervoltage: the new invisible threat of "all-electric"

In an article published on 10 December 2025, Le Soir reveals a largely underestimated emerging problem: undervoltage on the Walloon grid. Unlike overvoltage (caused by excess photovoltaic production in summer), undervoltage results from simultaneous excessive consumption — exactly the scenario caused by the massive electrification of heating.

The critical scenario described by ORES

ORES sets out a very concrete situation in black and white in its December 2025 presentation:

"If everyone recharges their car, cooks dinner and turns on the heat pump when they get home from work, is there a risk of a voltage problem? Yes. The voltage can drop to 200V, at which level the heat pump will not start." – ORES, internal presentation, December 2025

When thousands of heat pumps start up simultaneously in cold weather (return from work between 5pm and 8pm), combined with the charging of electric vehicles in the evening and meal preparation, the grid voltage can drop below 207V. At this critical level:

• 🚫 Heat pumps refuse to start (built-in thermal protection)
• ⚠️ Sensitive electronic devices malfunction (computers, modern household appliances)
• 📉 The quality of the electricity supplied deteriorates dangerously (risk of damage to equipment)
• 🔌 Photovoltaic inverters may also shut down (abnormal voltage detection)

👉 This is a key point: a customer equipped only with a heat pump for heating becomes dependent not only on the price of electricity and the availability of the grid, but also on the quality of the local voltage — a parameter over which they have absolutely no control and which deteriorates precisely when they need it most.

High voltage: power becomes scarce (and sometimes refused)

The statement "high voltage is already saturated everywhere" is no exaggeration. ORES provides a very telling snapshot of the situation at Elia's transformer stations (high-voltage transmission network):

In short: 27 substations are already refusing power, 58 will refuse power within five years if no major changes are made, and only 35 out of 122 substations (29%) seem capable of withstanding the shock in the medium term. The very notion of a "guaranteed connection" is becoming obsolete.

ORES states explicitly that current contracts guarantee "the full power requested regardless of the time or season", but in many cases this permanent band is no longer a realistic/appropriate solution.

2026 tariffs in Wallonia: an admission of powerlessness disguised as "modernisation"

Faced with this critical situation, the CWaPE (Walloon energy regulator) unveiled a major tariff reform in December 2025, to be implemented in 2026. The official objective, formulated in administrative language? "To match production and consumption in order to reduce constraints on the grid and control the cost of infrastructure investments".

Pragmatic translation: the grid can no longer guarantee constant power to everyone, all the time. Consumers are now encouraged — or forced — to shift their usage to times when the grid is less busy.

A revealing legal framework

The Walloon tariff decree, explicitly cited by the CWaPE, sets out two principles that appear contradictory but reveal the reality:

"Consumers who do not wish to contribute flexibility to the energy system should not be financially penalised by the new tariff structure... [but] each tariff component encourages network users who so wish to consume electricity when it is abundant on the network." – Article 4, §2, paragraph 2, 27 of the Walloon tariff decree

In other words: you are not officially being forced... but if you do not change your habits, you will pay significantly more.

New tariffs for 2026

Impact tariff and dynamic pricing: who is it for?

The CWaPE is very clear about the profile required for flexible tariffs. Consumers must:

• ✅ Have the technical capacity (or time) to start up high-consumption appliances at times when prices are low
• ✅ Avoid running these high-consumption appliances at the most expensive times
• ✅ Follow the price curves communicated the day before for the following day
• ✅ Organise their daily consumption accordingly

PV + PAC: a logical combination... but highly seasonal (and that changes everything)

Let's be honest and nuanced: PV + PAC can be excellent for much of the year. In mid-season (March-April, September-October), the combination works remarkably well:

• 🌤️ Efficient heat pump: moderate temperatures = high COP (3.5 to 4.5)
• ☀️ Sun present: long days, adequate sunshine
• ⚡ Usable PV production: directly powers the heat pump during the day
• 💰 Real savings: high self-consumption, reduced bills

The argument that "PV + heat pump = perfect combo" is therefore not entirely false. It is incomplete. Because the critical moment for the Belgian/Walloon grid is precisely when this beautiful mechanism breaks down:

• ❄️ When it is cold (maximum heating required)
• 🌑 When it is dark (short days from 8 a.m. to 4 p.m.)
• ☁️ When the sky is overcast (grey weeks from November to January)
• 🏠 When everyone returns home (peak 5pm-9pm)
• 📉 When the heat pump is in highest demand (continuous operation in very cold weather)

Winter timing mismatch: the Achilles heel of the system

This is not an ideological judgement against PV or heat pumps. It is an unavoidable physical mechanism:

1. Heating demand is correlated with cold weather (direct proportionality)
2. Sunshine is minimal in winter (8 hours of daylight, of which 4-5 hours are usable)
3. Peaks occur in the late afternoon/evening (after sunset)
4. The COP of heat pumps drops with temperature (COP 2-2.5 at -5°C vs 4-5 at +7°C)

And it is precisely in this scenario that "all-electric, uncontrolled" becomes a risky strategy if there is no storage, no control and no backup.

Removing a functional heating system (gas/oil): sometimes counterproductive

In the frenzy of the "fossil fuel hunt", one practice is becoming widespread and is even encouraged by certain regional subsidies: dismantling a perfectly functional oil or gas boiler to install an all-electric heat pump. However well-intentioned this approach may be, it poses several major problems.

The illusion of energy savings in real-world conditions

A customer switching from an oil boiler (90% efficiency) or gas boiler (95% efficiency) to a heat pump (average annual COP of 3.5-4) will indeed achieve substantial savings... on an annual average. But what about during critical winter periods?

These additional 625-1000 kWh of electricity are added to the grid demand at the worst possible times (cold spells, evenings without sunshine, consumption peaks). What if the grid fails? No more heating at all. No more cooking. No more basic comfort.

Resilience sacrificed on the altar of dogmatic electrification

A hybrid heating system (heat pump + fossil fuel boiler for backup/supplementary heating) offers unrivalled robustness:

• ✅ Economic optimisation: the heat pump operates when it is cost-effective (high COP, cheap electricity, grid available)
• ✅ Security of supply: the boiler takes over in the event of a grid failure, undervoltage, extreme cold spell or prohibitive tariffs
• ✅ Relief for the grid: during critical peaks, the heating automatically switches to fossil fuel, immediately freeing up electrical capacity for other users
• ✅ Extended service life: both systems operate less intensively, reducing wear and tear and breakdowns
• ✅ System consistency: this is in response to ORES, which explicitly states that "everything right now" is no longer sustainable

"Keeping a boiler operational as a backup is not an ecological betrayal, it is energy life insurance. The real waste is to throw away operational equipment that still has 10-15 years of potential life left in order to install another system that is totally dependent on a faulty electricity grid. Pragmatic ecology is what works every day, in all weathers, without compromising the comfort and safety of residents." – Wattuneed philosophy

Pragmatic solutions: flexibility, storage, hybridisation

Faced with the impasse of "uncontrolled all-electric", three strategic axes emerge from the official documents of ORES and CWaPE:

1. Flexibility: definition and variations

ORES defines flexibility as "the ability to modify one's energy injection or withdrawal profile in response to a signal, in order to provide a service to the electricity system and/or obtain a financial advantage".

This flexibility can be broken down into three levels:

2. Energy storage: the key to autonomy and resilience

Installing a storage battery radically changes the situation and transforms a vulnerable PV+HPC installation into a robust system:

• 📦 Maximised self-consumption: PV energy produced during the day is stored for use at night and in the morning
• ⚡ Peak shaving: the battery powers the heat pump and appliances in the evening (5pm-10pm), avoiding strain on the grid at critical times
• 🔋 Emergency backup: in the event of a grid outage or local undervoltage, the battery maintains essential equipment (critical circuits or the entire house, depending on size)
• 💰 Smart tariff arbitrage: charging during off-peak hours (low tariff), discharging during peak hours (high tariff) → substantial savings with Impact/dynamic tariff
• 🌍 Network service: possibility of participating in commercial flexibility mechanisms (remuneration by the DSO)

Battery sizing according to usage

3. The hybrid inverter: the intelligent energy conductor

The hybrid inverter is the brain of your modern solar installation. Unlike a conventional PV inverter (which only feeds solar energy into the grid or powers the home), the hybrid inverter intelligently manages three simultaneous flows:

1. Photovoltaic production: DC → AC conversion + multi-string MPPT optimisation
2. Battery storage: charging/discharging according to a programmed strategy (self-consumption, off-peak hours, tariff arbitrage)
3. Electricity grid: bidirectional withdrawal/injection according to instantaneous needs and current tariffs

The advanced modes of modern inverters (Sofar ESI, Deye, WKS EVO) allow, in particular:

• 🌙 Off-peak mode: battery charging from the grid when electricity is cheap (11 p.m. to 7 a.m.), discharging during peak hours
• 🏠 Self-consumption mode: maximises local use of PV energy, minimises grid injection
• 🚨 Backup/EPS mode: automatically switches to battery power in the event of a grid outage or detected undervoltage
• ⚖️ Dynamic arbitrage mode: financially optimises charging/discharging according to impact/dynamic tariffs (with integrated weather forecasts)
• 🔌 Zero injection mode: prevents any grid injection (saturated areas, unfavourable prosumer tariff)

4. Vehicle-to-Grid (V2G): your EV becomes a giant battery

An emerging but promising technology could revolutionise domestic energy flexibility: Vehicle-to-Grid (V2G) or "vehicle to grid/home". The principle? Use your electric vehicle's colossal battery as a storage system for your home.

Why V2G is a game changer

• 🔋 Colossal capacity: a 60 kWh EV battery = 12 times a 5 kWh domestic battery
• 🏠 Home power supply in the evening: the EV returns the stored electricity to power heat pumps, appliances and lighting
• 💰 Massive tariff arbitrage: charge during off-peak hours (or during the day if you work from home), discharge during peak hours
• ⚡ Paid network services: participation in the DSO's commercial flexibility mechanisms (additional income)
• 🌍 Grid relief: avoids simultaneous consumption peaks in the evening

Concrete example of V2G use:

Discover this technology: 🔗 EV & V2G batteries: complete guide

Grid investments: billions needed... but when?

ORES has presented an investment plan structured around three major areas to modernise and strengthen the Walloon grid:

The main problem? These massive investments will take years to materialise (studies, authorisations, construction), require colossal budgets that will inevitably be reflected in electricity bills, and do nothing to alleviate the current saturation.

The article in L'Avenir on 10 December 2025 confirms this unequivocally: "The ORES investment plan needs to be revised upwards, which could mean a further increase in electricity bills".

In short, the network will not be up to standard until 2030-2035 at the earliest, while massive electrification (heat pumps, electric vehicles, industry) is already here and accelerating. The period from 2025 to 2032 will be critical, with growing tensions between explosive demand and limited supply. Individual solutions (storage, flexibility, hybridisation) are not optional: they are imperative for anyone who wants to maintain comfort and energy resilience.

What can individuals do in practical terms? The three possible architectures

Scenario A — "Pure electric" (heat pump + EV) without storage or backup

Configuration: Heat pump alone for heating + EV + possibly PV without battery

Advantages:

• ✅ Maximum theoretical decarbonisation (zero direct fossil fuels)
• ✅ Maximum eligibility for regional subsidies (depending on current policy)
• ✅ Simpler installation (single heating system)

Major disadvantages:

• ❌ Total dependence on the grid during critical periods (winter, evenings)
• ❌ Sensitivity to undervoltage: heat pump does not start at 200V (case documented by ORES)
• ❌ Extreme tariff sensitivity with dynamic tariffs: impossible to move the heating
• ❌ Maximum contribution to grid saturation at the worst times
• ❌ No resilience: grid failure = cold house immediately

Conclusion: Only suitable in very robust areas (ORES Group 4 substations), risky elsewhere. Not recommended by Wattuneed except in very specific cases.

Scenario B — "All-electric smart" (heat pump + EV + control + battery)

Configuration: HEAT PUMP + EV + sized PV installation + 10-20 kWh lithium battery + hybrid inverter + home automation control

Advantages:

• ✅ Maximised PV self-consumption (70-90% depending on size)
• ✅ Peak shaving: battery powers home + heat pump in the evening
• ✅ Partial resilience: backup for essential circuits or entire home (depending on inverter)
• ✅ Tariff arbitrage: substantial savings with Impact/dynamic tariffs
• ✅ High decarbonisation maintained
• ✅ Commercial flexibility participation possible (GRD remuneration)

Disadvantages:

• ❌ High initial investment (battery + hybrid UPS: +£5,000-8,000)
• ❌ Increased technical complexity (configuration, maintenance)
• ❌ Limited autonomy in mid-winter: 1-2 days maximum without grid connection

Conclusion: Excellent compromise if budget allows and you want to remain 100% electric. Future-proof solution recommended by Wattuneed for new builds or major renovations.

Scenario C — "Resilient hybrid" (heat pump + backup + control ± battery)

Configuration: Main heat pump + gas/oil boiler/wood stove backup + possibly PV + battery + automatic switchover control

Advantages:

• ✅ Maximum heating resilience: works in all weather conditions and at all grid voltages
• ✅ Grid relief during critical peaks (backup activated automatically)
• ✅ Intelligent economic control: heat pump when COP is favourable + low tariff, backup otherwise
• ✅ Consistent with grid reality: responds to ORES' call to end "everything all the time"
• ✅ Utilisation of existing equipment: no waste if boiler is functional
• ✅ Easy maintenance: two independent systems = redundancy

Disadvantages:

• ❌ "Less pure" decarbonisation (but often more robust systemically)
• ❌ Double maintenance: heat pump + boiler (but limited auxiliary use = low wear and tear)
• ❌ Potentially reduced subsidies depending on regional policy

Conclusion: The most realistic and pragmatic scenario in Wallonia, where reliable access to electrical power is becoming problematic. Highly recommended by Wattuneed for renovations where a functional boiler already exists, or for areas identified as fragile (ORES Group 1-2 substations).

Wattuneed recommendations: checklist for a resilient installation

Conclusion: true ecology is what works in January at 7 p.m.

If we want an energy transition that works every day, in all weather conditions, including during cold spells and evening peaks, we must move away from the simplistic slogan "PV + PAC = universal solution".

ORES documents explicitly and unambiguously:

• 📉 Physical limitations (maximum current, critical voltage variations)
• ⚠️ The massive vulnerability of part of the LV network (10,000 circuits out of 70,000)
• 🚫 The current saturation of 27 HV substations + 58 additional ones by 2030 without flexibility
• ❄️ The concrete scenario where the heat pump may not start under low voltage (200V)
• 🔄 The end of the "everything, everywhere, all the time and right now" model

For its part, the CWaPE is clearly steering tariff rules and regulations towards:

• ⏰ Time-shifted consumption (automatic dual hourly rates, Impact, dynamic pricing)
• 📱 Active consumer adaptation (prices communicated the day before, daily monitoring, control)
• 💰 Marked tariff differentiation between those who adapt and those who suffer

The electrification of heating and transport is an ecological necessity — no one at Wattuneed disputes that. But it must be accompanied by:

1. 💾 Massive storage to smooth out peaks and guarantee autonomy
2. 🔄 Intelligent flexibility to adapt demand to available supply
3. 🌡️ Hybrid systems to guarantee real energy resilience
4. ⏰ Precise time management via dynamic tariffs, home automation and automation

"Abandoning a functional fossil fuel heating system to install an all-electric heat pump without storage, control or backup is, given the current state of the Belgian grid as documented by ORES and CWaPE, a high-risk decision. Saving 200 litres of fuel oil in winter only to find yourself without heating during a power outage, local saturation or breakdown is not environmentally friendly: it is energy recklessness." – Wattuneed SPRL

At Wattuneed, we believe in a pragmatic, resilient and functional energy transition. Our solutions combine:

• ☀️ Sized photovoltaics (production = annual consumption)
• 🔋 Lithium battery storage (10-20 kWh depending on usage)
• ⚡ Smart hybrid inverters (advanced modes, backup, arbitration)
• 🌡️ Hybrid approach where relevant (heat pump + backup heating)
• 📱 Home automation control (automatic optimisation without constraints)

Because a house without heating in the middle of winter is not environmentally friendly for anyone. Because true environmentalism is what works every day, in all weather conditions, without compromising the comfort and safety of the inhabitants.

❓ Frequently asked questions (complete FAQ)

Is it still a good idea to install a heat pump in Belgium in 2025-2026?

Yes, but not on its own. A correctly sized heat pump, combined with a storage battery (minimum 10-15 kWh), a smart hybrid inverter and, ideally, a backup system (wood, gas, oil), remains an excellent solution. The important thing is not to be 100% dependent on the electricity grid during peak hours (5pm-10pm) and during periods of potential undervoltage. ORES explicitly documents the risks of the heat pump not starting at 200V.

How many kWh of battery power are needed for a residential installation with a heat pump?

Sizing according to profile:

• Minimum viable: 10 kWh → covers night-time needs (3-4 kWh) + 3-4 hours of heat pump use in the evening (5-6 kWh) + safety margin
• Recommended optimum: 15-20 kWh → almost complete 24-hour autonomy except in very cold weather, possible participation in DSO flexibility
• Maximum comfort: 25-30 kWh → multi-day backup, aggressive tariff arbitrage, commercial flexibility resale

Prioritise modular systems (Sofar BTS, Pylontech US5000, Delong) that can be expanded as needs evolve.

Will Impact tariffs and dynamic pricing be mandatory in 2026?

No, but dual hourly rates are. The CWaPE clearly states:

• Two-tier pricing: automatic and non-optional for everyone (mandatory switch)
• Impact pricing: optional, requires an R3 smart meter + shiftable loads + explicit request to the supplier
• Dynamic pricing: optional, requires daily monitoring and active management

Interesting if installed with a battery + home automation (automatic optimisation). Otherwise, classic dual hourly rates are sufficient without any major penalties (but expect a difference between peak and off-peak rates).

Has my current PV installation (without battery) become obsolete?

No, but it can be improved. It remains useful for reducing bills (instantaneous self-consumption + remuneration for feed-in according to contract). To maximise resilience and self-consumption (70-90%), adding a battery via AC Coupling is strongly recommended. Wattuneed offers retrofit solutions to add:

• Hybrid inverter (Deye, Sofar, WKS) in parallel with the existing PV inverter
• Modular lithium battery (5-20 kWh)
• Smart control (off-peak modes, backup, arbitrage)

See guide: AC Coupling: 6 possible configurations

Will the Belgian grid really "crack" in the coming years?

The term "collapse" is excessive, but the constraints will be very real and measurable. ORES documents in black and white:

• 27 high-voltage substations are already refusing any new connections (group 1)
• 58 additional substations will be saturated by 2030 with no flexibility (group 2)
• 10,000 out of 70,000 LV circuits vulnerable (overvoltage AND undervoltage)

Expected consequences for 2025-2032:

• Refusal of commercial connections (charging stations, battery parks, industries)
• Localised undervoltage (residential areas with high density of heat pumps/electric vehicles)
• Possible targeted outages (technical flexibility as a last resort)
• Highly differentiated tariffs (indirect penalty for non-flexibility)

Network investments will take at least 10-15 years. Critical period 2025-2032 → resilient individual solutions imperative.

Is keeping my old oil/gas boiler as a backup really environmentally friendly?

Yes, from a holistic perspective. Several angles:

1. Equipment carbon footprint: Discarding a functional boiler (10-15 years remaining) = manufacturing + transport + installation of new heat pump + recycling of old boiler + waste. Significant immediate carbon impact.
2. Reduced heat pump efficiency in very cold weather: Heat pump forced to -10°C with COP 1.5-2 consumes 500-650 Wh of electricity per kWh of heat. If the electricity is produced by gas/coal power stations (Belgian winter mix), the indirect carbon footprint is similar or even worse than a direct boiler.
3. Network relief = less investment: Auxiliary heating activated 10-15% of the time (cold peaks) frees up network capacity → less reinforcement → less concrete/copper/steel → favourable overall balance.
4. Resilience = less energy insecurity: Cold homes during grid failures = major health and social problem.

Wattuneed conclusion: Intelligent hybridisation (80-90% heat pump + 10-20% backup) is often more environmentally friendly overall than dogmatic 100% electrification in a fragile grid context.

What should I do if my neighbourhood is identified as an area prone to inverter failures (power surges)?

Concrete actions:

1. Check via ORES map: Interactive map of voltage anomaly zones
2. Inverter configuration: Extended voltage range settings (according to standards), anti-dropout time delays
3. Zero injection mode: If there are chronic power surges, activate zero injection mode (local consumption only, surplus to battery)
4. Buffer battery: Local storage drastically reduces grid injection (absorption of surplus)
5. Contact GRD: Report via ORES support (network reinforcement work planned according to priority areas)

How can I tell if my local HV substation is saturated or nearing saturation?

Indirect indicators:

• Industrial/commercial projects rejected in your municipality (local press, municipal councils)
• Longer waiting times for new connections (PV installers report blockages)
• Repeated incidents on the LV network (micro-cuts, voltage variations)

Official information: ORES does not publish a detailed public map of saturated substations (commercial confidentiality), but provides specific information via:

• Preliminary connection request (ORES response indicates availability)
• Regional parliamentary questions (public reports)
• Specialised local press

Does Wattuneed offer complete turnkey solutions with support?

Yes, complete process:

1. Study phase: Sizing using free tools (Toolbox) + personalised telephone advice
2. Design phase: Customisable solar kits (PV + hybrid inverter + battery + accessories) tailored to your consumption profile and heating system
3. Installation phase: Network of certified partner installers (depending on region) OR equipment delivered for installation by your electrician
4. Operation phase: Dedicated after-sales support (Help Centre) + detailed technical guides (Expert Blog)
5. Optimisation phase: Advanced configuration guides (inverter modes, pricing strategies, monitoring)

📞 Need personalised advice for your project?
Wattuneed Support Centre • PV technical blog • Free toolbox

Wattuneed SPRL – Your Belgian partner in photovoltaic and renewable energy solutions since 2010. Technical expertise, personalised support, resilient solutions adapted to the Belgian grid.
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