Short answer
What you need to know first.
For large roof areas in Thurgau, the key question is not how many modules theoretically fit. What matters is whether roof, structure, grid connection, metering concept, permitting path, incentive programme and electricity use fit together. Systems below 100 kW, systems from 100 kW and systems without self-consumption can follow different Pronovo incentive logics; in addition, the grid operator must assess the technical connection capability of the specific site.
Important
This page provides general guidance for large PV roof areas in Canton Thurgau. It does not replace property-specific roof, structural, fire-protection, grid, legal, tax or incentive assessment. Incentive programmes, tariffs, grid-connection conditions and permitting procedures must be checked for each project against the current status of Pronovo, canton, municipality and responsible grid operator.
Decision points
What determines the right path.
Usable roof area is not the same as visible roof area. Rooflights, skylights, roof structures, fire compartments, snow guards, maintenance paths, fall protection, shading, roof age and later refurbishment can significantly change the usable area. On large roofs, a roof survey therefore comes before the yield calculation.
Load-bearing capacity determines system choice and layout density. Especially on halls, barns and older commercial roofs, dead load, snow, wind, ballast or penetrations must be assessed for the specific object. A lightweight mounting system does not replace structural assessment if roof reserves or refurbishment needs are unclear.
The incentive path depends, among other things, on capacity and self-consumption. Pronovo distinguishes one-time payments for small systems, large systems and high one-time payments for systems without self-consumption. Which logic fits must be checked before submission against current Pronovo rules, commissioning date and project model.
Grid connection can be the bottleneck for large systems. Connection capacity, feed-in point, meter location, protection concept, transformer, grid reinforcement, reactive power requirements and commissioning documents belong early in planning. Without grid clarification, full roof coverage is a technical assumption, not a secured project.
Self-consumption, pure feed-in or roof leasing lead to different projects. Farms, cold stores, depots, production halls and multi-tenant properties have different load profiles. The system becomes economically meaningful only when electricity use, billing, operation and owner role are planned together.
Sequence
How the project stays cleanly managed.
- 1
Record roof and propertydocument roof build-up, age, refurbishment window, structure, waterproofing, drainage, fire compartments, access, fall protection, shading and existing technical structures. This creates a realistic first usable area instead of a generic roof-area assumption.
- 2
Define the usage modelcompare self-consumption, ZEV or vZEV assessment, pure feed-in, roof lease, later battery or wallbox integration and possible load shifting. The model affects inverters, metering, incentive path and operator duties.
- 3
Involve the grid operator earlyclarify connection request, available connection capacity, feed-in point, metering concept, protection requirements, meter conversion and possible grid reinforcement. For large systems, this should not happen only after material ordering.
- 4
Check incentive and permitting pathclassify Pronovo programme, current tariffs, commissioning conditions, certification, cantonal or municipal requirements and notification or permit questions separately. An incentive approval, grid release and building-law decision are different project steps.
- 5
Calculate variants before quotingcompare full coverage, partial coverage, east-west layout, south layout, battery option, feed-in limitation, self-consumption optimisation and later expansion technically and economically. The best solution is the one that works for roof, grid and operation together.
Checklist
Questions to settle before the quote.
- Check roof condition, structure, fire compartments and current roof use before module layout
- Choose KLEIV, GREIV or HEIV based on capacity, self-consumption and project goal, not instinct
- Clarify grid connection, metering, transformer or reinforcement needs before the final quote
- Compare self-consumption, roof lease, direct marketing or feed-in as clean variants
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.