Short answer
What you need to know first.
A PV bidirectional wallbox turns an electric car into building storage only when the vehicle, wallbox, controls and electrical installation work together for V2H. In Canton Solothurn, the fixed installation must be carried out by a licensed specialist under Art. 6 NIV; tax treatment depends on the evidenced storage share of the permanently installed wallbox.
Important
As of 24 July 2026, a bidirectional wallbox is not automatically a building- or grid-feed-in system. V2H requires a demonstrably compatible vehicle-wallbox combination and an electrical installation designed for it; V2G needs its own grid-side review.
Decision points
What determines the right path.
The operating mode is the first filter: EnergieSchweiz distinguishes V2H for feeding back into the building, V2G for feeding into the public grid and V2L for individual devices. Anyone aiming to cover night demand in the building must plan V2H; a V2L connection or simple PV-surplus charging does not achieve that purpose.
Compatibility is not a product category but a specific pairing: EnergieSchweiz requires both a bidirectionally capable electric car and a suitable wallbox that communicates with the car. Until cross-manufacturer V2X communication is expected around 2028, proprietary solutions cannot be combined freely.
The fixed installation remains subject to authorisation: Art. 6 NIV requires an ESTI installation permit for creating or altering electrical installations. ESTI Directive No. 220 also requires an initial inspection, final inspection and safety certificate before commissioning; a wallbox must therefore not be treated as an afterthought outside electrical planning.
PV and grid operation must be checked separately: for parallel operation of an electricity-generating installation, ESTI Directive No. 220 requires a connection request and consent from the responsible grid operator. V2H planning must neither replace this existing PV connection assessment nor confuse it with V2G approval.
Tax treatment is narrower than the purchase price: the Solothurn tax manual of 24 April 2025 allows only the evidenced storage share of a bidirectional wallbox installed on the property, not the vehicle battery. The deduction is excluded for new builds or replacement builds, so the invoice and evidence of use belong in the project file.
The location affects inspection: for charging stations in public spaces, ESTI states a five-year inspection period under item 2.3.3 of the NIV Annex. On private property, the wallbox’s inspection period follows that of the building; a public garage and a private single-family-house installation must therefore not be treated alike.
Sequence
How the project stays cleanly managed.
- 1
Set the target operating modelfirst decide whether the goal is PV-surplus charging, V2H for the owner’s building, V2G or only V2L. Record the intended operation and the vehicle’s required minimum reserve in writing, because V2H is not an automatic consequence of an ordinary wallbox.
- 2
Evidence compatible componentshave the vehicle model, software version, wallbox and controller confirmed as a specific V2H combination. EnergieSchweiz requires bidirectional capability of both devices; general statements such as “V2X-ready” do not replace compatibility evidence.
- 3
Survey the building and PV system technicallyrecord the service connection, main distribution board, PV inverter, existing battery, metering, protection concept and relevant loads such as a heat pump. This is the basis for the electrical specialist to assess how charging, feed-back and the existing PV system work together without conflicting protection functions.
- 4
Carry the grid-operator process alongside the projectalign the PV connection request and consent for parallel grid operation with the responsible grid operator. If V2G is being considered, clarify its separate process before ordering; a V2H solution must not be understood as automatic feed-in approval.
- 5
Carry out and document authorised electrical workengage a business with an installation permit under Art. 6 NIV for the fixed installation. Before handover, the initial inspection, final inspection and safety certificate required by ESTI Directive No. 220 must be available; retain the diagram, operating instructions and test records.
- 6
File tax documents separatelyfor a bidirectional wallbox permanently installed on the property, retain the invoice, technical functional evidence and documented storage share. The Solothurn tax manual requires evidence of the extent to which the station is used as storage rather than merely to charge the car.
Checklist
Questions to settle before the quote.
- Separate V2H, V2G and V2L: only V2H supplies the owner’s building from the vehicle
- Check the vehicle and wallbox as one specific, mutually compatible V2H combination
- Coordinate the PV inverter, service connection, protection concept and grid-operator process before ordering
- Document the invoice and evidence for the wallbox’s tax-relevant storage share separately
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.
- Bidirectional charging: electric car as energy storageEnergySchweiz
- Tax manual § 27 No. 4: operating a photovoltaic systemCanton Solothurn
- ESTI Directive No. 220: electricity-generating installationsSwiss Federal Inspectorate for Heavy Current Installations ESTI
- ESTI notice: inspection periods for charging stationsSwiss Federal Inspectorate for Heavy Current Installations ESTI