Short answer
What you need to know first.
In the WWZ grid area, new PV systems have had to limit export to no more than 70% of DC module capacity since 1 January 2026; the same applies when an inverter is replaced. The limit applies only to grid export and still allows self-consumption, battery use and controllable loads. Planning should therefore first establish the grid area and then the technical configuration.
Important
As of 2026, the 70% rule in this guide expressly relates to the WWZ grid area, not all of Canton Zug. For existing systems without an inverter replacement, WWZ states that the further timetable is set by the respective grid operator; change the system only in response to a specific technical requirement.
Decision points
What determines the right path.
The grid area determines whether the rule applies. The WWZ requirement applies in its own grid area from 1 January 2026, not automatically to every address in Canton Zug; the responsible distribution network operator must therefore be confirmed before detailed planning.
DC module capacity is the decisive value. WWZ limits export capacity to 70% of the modules’ DC rated capacity; a larger module area is not prohibited, but the export peak must be handled separately in the design.
An inverter replacement is a specific trigger. WWZ also applies the 70% rule to existing systems when a new inverter is installed; for a refurbishment, configuration must therefore be included in the technical quotation.
The limit is intended to reduce midday peaks, not prevent solar use in the building. WWZ identifies the inverter and EMS as implementation points; self-consumption through a heat pump, boiler, wallbox or battery remains possible and belongs in load planning.
WWZ quantifies the possible yield reduction. For export limited to 70%, WWZ gives a maximum of 3% of annual yield; that figure concerns curtailment, not the project’s overall economics.
Existing systems without an inverter replacement are not automatic cases. WWZ explains that further implementation and timing for existing systems are set by the respective grid operators; an existing system should therefore not be reconfigured pre-emptively without a specific request.
Sequence
How the project stays cleanly managed.
- 1
Confirm the grid areabefore sizing anything, check whether the property is in the WWZ grid area. At an address outside that area, the requirements of the local distribution network operator apply, not the WWZ 70% rule automatically.
- 2
Classify the system casenew PV systems and existing systems with an inverter replacement fall within the WWZ case described since 1 January 2026. Record the replacement not merely as service work, but as a design change.
- 3
Separate capacity valuesshow the modules’ DC rated capacity and export capacity limited to 70% distinctly in the diagram, quotation and documents for the grid process.
- 4
Choose the implementationdecide with the electrical contractor whether the limit is configured in the inverter or the EMS. The chosen solution must reliably keep the export limit without unnecessarily blocking self-consumption.
- 5
Include loadscapture the heat pump, boiler, wallbox and battery storage in the EMS concept. These loads are not the export limit itself, but can use PV electricity in the building when grid export reaches its 70% boundary.
- 6
Document the configuration and verify it before commissioningcompare the limit set in the inverter or EMS with the modules actually installed. Repeat the same check for any later inverter replacement.
Checklist
Questions to settle before the quote.
- Before requesting a quote, determine whether the property is in the WWZ grid area and the 70% requirement therefore applies
- Show DC module capacity and permitted export capacity separately in the technical concept
- Specify an inverter or EMS that can demonstrably be configured for the limit
- Treat an existing system with an inverter replacement as a new planning case
FAQ
Common questions on this topic.
Sources
Official sources & references.
The responsible authorities are decisive. Always verify binding details – amounts, deadlines and conditions – for your specific property against the current status of the respective authority.