A hybrid inverter emergency power supply has become a crucial element for many homeowners who want protection against power outages and full use of their self-generated solar energy at any time. It links the PV system, battery storage, and backup switching into an autonomous energy system — without requiring extensive additional technology.

However, Backup is not always real backup. For emergency power to work properly when it counts, you need proper system planning, suitable hardware components, and compliance with technical regulations.

What Is the Difference Between Emergency Power, EPS, and a True Backup Solution?

Hybrid inverters are often marketed as automatic emergency power systems — but many devices only offer an EPS (Emergency Power Supply) function.

In practice, there are three types:

Mode of Operation	Features	Advantages	Limitations	Typical Uses
EPS / Partial Backup	Fast switching (model-dependent, a few ms)	Easy integration	Only selected sockets/circuits	Refrigerator, router, lighting
Full Backup (4-pole ATS)	The entire house can be supplied	Maximum resilience	More complex protection technology	Outages lasting hours/days
UPS per IEC 62040	0 ms switchover (no interruption)	Ideal for sensitive loads	Not suitable for entire household loads	Servers, medical equipment

A hybrid inverter emergency power system is not automatically a UPS — this must be clearly communicated to customers.

Which Components Are Required for a Hybrid Inverter Emergency Power System?

A reliable blackout solution is typically built as follows:

System architecture (compliant with German, Austrian, and Swiss standards) PV strings → Hybrid inverter → Battery → Backup sub-distribution → Critical loads with a 4-pole Automatic Transfer Switch (ATS) that cleanly switches L1/L2/L3/N

→ Prevents feed-back into the public grid → Defines neutral conductor during island operation

This topology is the standard recommendation for full-backup systems according to technical guidelines.

Standards & Grid Connection Rules in Germany, Austria & Switzerland

Emergency power systems must always be designed in accordance with applicable standards and manufacturer specifications.

Germany

• VDE-AR-N 4105:2018-11 – Grid connection for generating plants
• VDE-AR-N 4100:2019-04 – Requirements for meter cabinet/house connection
• Local utility operator TAB specifications
• MaStR registration for PV and storage units

Austria

• TOR Erzeuger Type A v1.3 (10.06.2024)
• OVE E 8101

Switzerland

• NIN SN 411000 (2025)
• VSE NA/EEA-NE7

Non-compliance can result in:

• No grid approval
• loss of warranty
• safety deficiencies

Why Is a 4-Pole Transfer Switch (ATS) Essential?

For a safe hybrid inverter emergency supply, the neutral conductor (N) must be defined during island mode.

A 4-pole ATS switches L1 / L2 / L3 / N, ensuring:

• no back-feeding into the public grid
• proper formation of a new neutral reference point
• correct operation of protection systems

This requirement is anchored in standards such as DIN EN 60947-6-1.

How Should the System Be Properly Sized?

Emergency power design follows different principles from normal grid-connected planning:

Inverter Output Power

Motor loads (heat pumps, fridge compressors, etc.) draw 2–3× higher inrush current: ➡ EPS output is often insufficient ➡ Full backup requires phase planning and load prioritization

Tip: Cleanly separate critical and non-critical loads.

Battery Capacity

Rule of thumb:

Autonomy / (DoD × η)

Example:

7 kWh usable capacity typically covers 6–12 hours of household base consumption.

Transfer Times

• EPS: usually < 10 ms → most household devices tolerate this
• ATS full-backup: 100 ms to several seconds
• For zero-downtime loads → separate UPS required

Protection & Safety: What Must Be Considered?

Hybrid inverter emergency power systems must meet higher protection requirements:

Protection Measure	Regulation	Purpose
AC/DC surge protection	DIN VDE 0100-443/534/712	Protection against lightning & grid faults
Proper RCD selection	DIN VDE 0100-420	Residual-current safety
Battery safety	VDE-AR-E 2510-2	Fire safety & installation
Documentation/testing	DIN VDE 0100-600 + FNN Annex E forms	Certified handover & approval

➡ Many existing homes require meter cabinet upgrades per VDE-AR-N 4100.

Which Manufacturer Solutions Are Common in D-A-CH?

• SMA AC-Backup – robust full-backup integration
• Fronius GEN24 Plus – PV Point (EPS) + full-backup option
• Huawei Backup Box – 1-/3-phase, paired with SUN2000
• GoodWe ET-Series – fast EPS switching

Important: Always follow the manufacturer’s installation documentation.

Checklist: When Is EPS Enough & When Do You Need Full-Backup?

Requirement	Recommendation
Router, lighting, laptop, fridge	EPS is sufficient
Heat pump, cooking appliances, whole house	Full-backup necessary
IT/medical equipment	Additional UPS required
A utility requires a defined islanding	4-pole ATS mandatory

In short:

If comfort and independence are priorities → choose a real backup solution.

Planning Mistakes Installers Must Avoid

• Undefined neutral conductor in emergency mode → protection devices fail
• Too many loads on backup circuit → battery overload → shutdown
• Missing documentation → no approval by the grid operator
• No surge protection → warranty issues & increased risk

A hybrid inverter emergency power supply is not plug-and-play — expert planning is essential.

A hybrid inverter emergency power system enables true energy independence:

➡ Power supply continues during outages ➡ Higher safety and comfort ➡ Solar production remains available even when the grid fails

Anyone who wants to ensure full compliance with regulations, safety engineering, and system planning should rely on experienced local professionals.

PVPro Solar GmbH plans & installs hybrid backup systems in full compliance with all D-A-CH regulations. → Request expert consultation now: PVPro Solar GmbH

Do I need a UPS for zero-downtime loads?

Yes — hybrid inverters do not meet the UPS standard IEC 62040.

Can the entire house be powered during an outage?

Only with full-backup systems using a proper 4-pole ATS.

Can the battery feed into the grid while grid power is present?

Yes — if VDE-AR-N 4105 and manufacturer rules are followed.

How long will the battery last during an outage?

Typically 6–12 hours, depending on consumption and battery size.

Must storage systems be registered in MaStR?

Yes — separately from the PV system.