Our assessment work in Bielefeld and East Westphalia covers the full range of PV and storage evaluation — from yield assessments for ground-mounted systems at the Teutoburg Forest to defect analysis of commercial rooftop systems in industrial areas. The TAB of Bielefelder Netz are our constant companion: without precise knowledge of the local connection requirements, no reliable assessment can be produced.
Bielefelder Netz GmbH operates the power distribution grid in Bielefeld serving approximately 340,000 inhabitants. In the commercial areas of Sennestadt and Brackwede, grid compatibility issues regularly arise with larger PV systems.
At the end of October 2024, the 10,000th photovoltaic system in Bielefeld was connected to the grid. According to Stadtwerke Bielefeld, the systems of up to 30 kW together exceed 79,000 kW of capacity and generate around 75 million kWh per year. Bielefelder Netz checks every system above 800 W for grid compatibility in advance. This allows it to identify bottlenecks before installation and to plan grid reinforcement in good time.
For assessments this has a practical consequence: for every Bielefeld system above 800 W a check result from the grid operator should exist. We request it in purchases, sales or defect disputes because it states any feed-in limits or conditions. Together with the commissioning report and the entry in the Market Master Data Register, it documents the connection history of the system.
Ground-mounted systems also have a local example with its own inspection questions. Since August 2024, Stadtwerke Bielefeld have been building the Schiefe Breede solar park on a former landfill in the Jöllenbeck district, with 4.158 MWp on 3.84 hectares. Completion was planned for spring 2025, and the expected yield is 4.3 GWh per year. On landfill sites we examine settlement of the landfill body and the foundations of the mounting structure, which must not damage the surface capping.
| Standard | Scope | Relevance for PV |
|---|---|---|
| VDE-AR-N 4100 | TAR low voltage | Mandatory: meter location, service entrance, protection concept |
| VDE-AR-N 4105 | Generation systems on LV grid | Mandatory for connection to the low-voltage grid |
| VDE-AR-N 4110 | TAR medium voltage | Mandatory for connection to the medium-voltage grid |
| Supplementary TAB Bielefelder Netz | Regional supplements | Grid operator-specific requirements |
| Requirement | Specification |
|---|---|
| Meter type | eHZ, three-point mounting |
| Surge protection | Type 1+2 combined arrester (mandatory for new systems) |
| SLS switch | selective circuit breaker upstream of the meter |
| Space reserve | 1 slot for smart meter gateway |
| Equipotential bonding | to main earthing busbar |
Balcony power plants up to 800 W can be registered through a simplified process at Bielefelder Netz.
Bielefeld is located in the Amprion control area. The responsible transmission system operator (TSO) is Amprion GmbH. Amprion is responsible for system stability in the extra-high voltage grid (220/380 kV). At the regional distribution grid level, Westfalen Weser Netz is also an important player.
| Level | Operator | Voltage Level | Relevance for PV/BESS |
|---|---|---|---|
| Transmission grid | Amprion | 220-380 kV | System stability, EEG feed-in |
| Distribution grid | Bielefelder Netz | 0.4-20 kV | TAB, grid connection, meter location |
| Customer system | System operator | 0.4 kV (LV) | PV array, BESS, inverter |
Regional factors for planning and assessment in Bielefeld:
Bielefeld's location at the Teutoburg Forest creates pronounced shading situations. South-facing slope systems benefit from higher yields, while north-facing locations lose up to 30% — detailed site assessments are essential.
Bielefeld's strong SME sector (Miele, Oetker, Schueco) invests in self-consumption PV. Economic feasibility assessments with self-consumption optimization and storage dimensioning are in high demand.
Outside the Bielefelder Netz service area, Westfalen Weser Netz takes over supply. The TAB requirements differ in detail — the grid operator jurisdiction must be clarified in advance.
Bielefeld's former textile factories (Ravensberger Spinnerei, Baumheier) are being repurposed. The sawtooth roofs are excellent for PV — but require structural reinforcement assessments.
| Occasion | Our Service |
|---|---|
| Acceptance assessment | TAB conformity check, defect report |
| Dispute with grid operator | Independent technical evaluation |
| Systems from 30 kWp, medium voltage, capacity bottleneck | Grid compatibility assessment, grid analysis, alternative concepts |
| Defect assessment | DIN VDE 0100-600, thermography, EL |
VDE-AR-N 4100 and 4105 (low voltage) or 4110 (medium voltage) plus supplementary TAB of Bielefelder Netz GmbH.
Exclusively through a certified electrical contractor. Details: Bielefelder Netz website.
Must comply with VDE-AR-N 4100 and supplementary TAB. Older cabinets (pre-2010): eHZ, surge protection, SLS. Cost: EUR 1,000-2,500.
Depends on system size and scope. Contact: info@pv-bess-assessor.com or +49 89 97 31 37 43.
For systems from 30 kWp, medium voltage, grid compatibility issues, disputes with the grid operator, acceptance of commercial systems.
We know the TAB of Bielefelder Netz from daily practice. Get in touch.
Contact Us| Address | Bielefelder Netz GmbH, Schildescher Str. 16, 33611 Bielefeld |
| Phone | 0521 51-0 |
| info@bielefelder-netz.de | |
| Website | Bielefelder Netz — TAB |
We assess nationwide. These pages summarise the TAB of each grid operator:
Augsburg Berlin Bonn Bremen Dortmund Dresden Düsseldorf Duisburg Frankfurt Hamburg Hannover Karlsruhe Köln Leipzig Mannheim München Münster Nürnberg Stuttgart
Last updated: 2026-09-28 | Author: Christoph S. Prestele, TUV-certified expert assessor | Source: Bielefelder Netz GmbH