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Solar panels · Backup
Backup storage: the power keeps flowing when the grid stops
During a grid outage, a conventional battery goes into safe mode and shuts down. With the backup function (EPS), the hybrid inverter switches to the battery in a fraction of a second: your priority circuits (fridge, lighting, internet, medical) stay powered for the duration of the outage.
- < 20 ms
- switchover
- Key circuits
- fridge, internet, lighting
- Hybrid EPS
- inverter required
Switch < 20 msnear-instant
Priority circuitsfridge, lighting, internet
How it works
How does backup work?
Backup requires a hybrid inverter with EPS and a compatible battery. Here’s what happens during an outage.
- Switchover < 20 ms
The inverter detects the grid outage and switches to the battery in under 20 milliseconds. Almost imperceptible: appliances don’t restart.
- Priority circuits Dedicated selection
We define the circuits powered in backup: fridge, freezer, lighting, internet, medical device. Not the whole house — to save the battery.
- Autonomy Depends on capacity
With 10 kWh and limited circuits (500 W average), backup lasts ~20h. The lower the consumption, the longer the battery lasts.
- Recharging during an outage Yes (if sunny)
During the day, the panels keep charging the battery even during a grid outage. Backup can last indefinitely if solar production covers consumption.
- Inverter required Hybrid EPS
Not all hybrid inverters do backup. You need the EPS (Emergency Power Supply) function. Check compatibility before buying.
- Installation Dedicated sub-panel
The backup circuits are grouped on a dedicated sub-panel, powered by the inverter during an outage. The electrical installation is adapted during the work.
* Real autonomy depends on the battery capacity and the consumption of the selected circuits.
Full transparency
Pros & cons of backup
Backup is added peace of mind, not always essential.
What makes it strong
- Continuity of essential circuitsFridge, freezer, internet, lighting: no interruption during outages.
- Near-instant switchoverUnder 20 ms: appliances don’t restart and data isn’t lost.
- Solar recharging during an outageDuring the day, the panels keep charging the battery even without the grid.
- Peace of mindEspecially if you depend on a medical device or if outages are frequent.
What you should know
- Extra costAn EPS hybrid inverter costs more than a standard one. So does the dedicated sub-panel.
- Not the whole housePowering the whole house in backup drains the battery very fast. We select the essential circuits.
- Outages are rare in BelgiumThe Belgian grid is reliable. Backup is a comfort, not a necessity for most.
- Compatibility to checkNot all inverters and batteries support backup. We check before recommending.
For which need
Is backup right for you?
Backup pays off in certain specific situations:
-
Medical dependence
Oxygen concentrator, dialysis machine, insulin fridge: backup keeps these vital devices running without interruption.
-
Large food stock
A full freezer loses its contents in 12–24h without power. Backup prevents the loss.
-
Remote work / internet box
During an outage, no internet means no work. Backup keeps the router and your office lighting running.
Partial or full backup?
Partial backup (selected circuits) is the most common and the most economical. Full backup (the whole house) requires a very large battery and a powerful inverter — rarely justified in residential settings. Start with a good home battery.
Glissez la poignée pour comparer
Case study · rural area, Province of Luxembourg
Frequent outages neutralised by solar backup
A home in a rural area where outages are frequent (storms, tree-cutting). The customer asked for backup on the fridge, freezer, lighting and internet. With 10 kWh and an EPS hybrid inverter, the circuits last ~18h during an outage — and recharge in the sun during the day.
- ~18hbackup autonomy
- 4 circuitspriority circuits secured
- < 20 msimperceptible switchover
Customer reviews
They chose wendows
5.0/5 · 1verified reviews
Compare the levels
Partial, full or no backup?
The level of backup depends on your needs and your budget.
| Critère | Partial backupVous êtes ici | Full backupVoir la gamme → | No backupVoir la gamme → |
|---|---|---|---|
| Protected circuits | Selected (3–5) | The whole house | None |
| Autonomy | 12–20h (10 kWh) | 3–5h (10 kWh) | 0 |
| Investment | Moderate | High (large battery) | The lowest |
| Battery required | 5–10 kWh | 15–20+ kWh | Any size |
| Inverter | Hybrid EPS | High-power hybrid EPS | Hybrid or standard |
| Peace of mind | Essential circuits | Total comfort | Outage = blackout |
| Ideal for | Residential, comfort | Medical dependence, remote area | Budget, reliable grid |
Indicative benchmarks. Autonomy depends on the consumption of the selected circuits.
- the system
Home battery
The battery is the basis of backup. Choose the right capacity for your needs.
See the batteries → - the chemistry
LiFePO4
The safest chemistry for backup: thermally stable, reliable in an emergency.
All about LiFePO4 → - the controller
Hybrid inverter
Backup requires a hybrid inverter with EPS. Not all of them do it.
See the inverters → - without backup
Standard battery
Storage without backup: evening self-consumption, but shuts down during an outage.
See standard storage → - to combine
Solar kit
The panels recharge the battery even during an outage. Size it for backup.
See the kits → - ↑ category
All things solar
An overview of our solar panels across Belgium.
Back to the solar guide →
Indicative pricing 2026
How much does storage with backup cost?
The extra cost of backup comes from the EPS hybrid inverter and the dedicated sub-panel.
See storage prices & returns →* Indicative ranges for installed equipment. The exact cost depends on the capacity and the number of backup circuits.
- EPS hybrid inverter €1,500–3,000installed, with backup function
- 10 kWh battery + backup €7,000–10,000complete system, installed
- Backup sub-panel €300–600dedicated priority circuits
- Reduced VAT 6%for renovation (home > 10 years old)
Backup FAQ
Your questions about backup
Does backup power the whole house? +
Generally no. We select the essential circuits (fridge, lighting, internet) to maximise autonomy. Powering the whole house would drain the battery in a few hours.
Is the switchover really imperceptible? +
Almost. The EPS switchover takes under 20 milliseconds. Appliances don’t restart and screens don’t flicker. Only very sensitive devices (some servers) might need a dedicated UPS.
Can backup be added to an existing battery? +
It depends on the inverter. If your hybrid inverter supports EPS, you just wire a backup sub-panel. Otherwise, the inverter has to be replaced with an EPS model.
How long does backup last? +
It depends on the battery capacity and the consumption of the circuits. With 10 kWh and circuits limited to ~500 W, backup lasts about 20h. During the day, the panels recharge the battery.
Does backup work at night? +
Yes, as long as the battery has charge. At night, without panels, the battery doesn’t recharge — autonomy depends on the remaining capacity. That’s why we select low-consumption circuits.
Is backup essential? +
No. The Belgian grid is reliable and outages are rare and short. Backup is added comfort, particularly useful in rural areas, in cases of medical dependence or to protect a food stock.
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