Site Acquisition & Project Development — which land is suitable for a solar park

In short: Suitable land is flat or gently south/southwest-facing, with good grid-connection availability, from roughly 5 hectares contiguous, free of exclusion concerns (protected areas, water management, soil protection). Before the first investment decision come three preliminary checks: grid connection, exclusion layer, owner willingness.

Criteria for suitable land

Exclusion layer — where construction is not possible

• Naturschutzgebiete (NSG, nature reserves), national parks, FFH (Habitats Directive) and SPA (Special Protection Area) sites: generally excluded.
• Landschaftsschutzgebiete (LSG, landscape protection areas): case-by-case assessment, often critical.
• Wasserschutzgebiete (water protection zones) Zone I/II: excluded; Zone III subject to conditions.
• Überschwemmungsgebiete (flood-risk areas) / HQ100: critical due to structural load and insurability.
• High-quality soils (high soil rating points): excluded in some regions under state law, especially for classic ground-mounted PV without an agri-PV concept.
• Priority and reserve areas for other uses (raw materials, transport).
• Heritage protection / sightlines.

Site criteria in detail

The table above lists the criteria, but in practice it is the combination that decides. A site 1 km from the grid connection with poor soil quality is often more attractive than one 200 m away with high-grade soil — because soil quality determines whether the project gets permitted at all, while grid distance only affects connection cost.

Proximity to grid connection: Every extra kilometre of line costs money (underground cabling, permits for line easements, possibly substation expansion) and time. As a rule of thumb, under 2 km is usually unproblematic; from 5 km the cable route itself becomes a permitting procedure of its own, with its own landowners and concerns to clear. The real order of magnitude only becomes binding once the responsible distribution grid operator answers the preliminary grid-connection enquiry (see sequence below).

Soil quality: Agricultural land with a high soil-rating score is restricted or excluded for classic ground-mounted PV in several German states, by decree or administrative guidance, to avoid competing with food production — the exact threshold (e.g. a soil-point range) varies by state and by the current decree; what governs is the applicable state rule at the time, not a nationwide fixed value. Agri-PV concepts (dual land use) can get around this restriction in part — see Agri-PV.

Slope: A south to southwest orientation with a gentle slope increases yield; north-facing slopes are unsuitable for classic mounting. Above roughly 15–20% incline, foundation costs rise noticeably (anchoring, erosion control), which makes many sites economically unattractive — this is an assessment from market observation, not a sourced hard threshold, since the actual cut-off depends on project and soil conditions.

Shading: Existing trees, buildings, or neighbouring structures to the south reduce yield disproportionately to the shaded area, because entire module strings can drop out. A shading analysis (sun-path diagram across the year) belongs in every serious site check before signing a contract.

Eligible-area rules under Section 37 EEG 2023/2024 — which land qualifies for support

Section 37 of the German Renewable Energy Act (EEG) defines which land categories are eligible to take part in the EEG auction for ground-mounted installations (the eligible-area rules). These include, among others, side strips along motorways and railway lines (up to a width defined in the law), brownfield conversion sites (formerly military or commercial use), and — where states have opened them up — certain arable and grassland areas in disadvantaged regions. German states may open up or restrict additional land for their territory by ordinance, so the actually usable area differs between states. Anyone building outside the EEG-eligible area depends on PPA marketing instead — see PPA and EEG auction for the auction mechanics themselves. What governs is always the current text of Section 37 EEG and the applicable state ordinance — both should be checked before securing the site, not only before filing the application.

Land registry security and priority notice

A usage or lease agreement alone does not protect against the site being marketed to a second party, or sold to a third party, during project development. Legal certainty comes from a priority notice in the land registry (Vormerkung, Section 883 BGB) in favour of the project developer — it secures the later claim to a usage right or easement and holds against any subsequent buyer of the land. It is also common to register a limited personal easement or a heritable building right (Erbbaurecht) in favour of the project company once the agreement reaches its binding phase. A purely contractual commitment through an option agreement without a land-registry entry is normal in the early screening phase, but before larger investments (expert reports, grid-connection fees) at least a priority notice should be in place.

Usage agreement vs. lease agreement — the legal difference

Both contract types occur in practice but differ in legal classification: a lease agreement (Sections 581 ff. BGB) grants the right to use the land including its yield, and is typically the contract model where the land was previously farmed. A usage agreement (a contractual permission arrangement of its own kind, often combining elements of tenancy and lease law) is frequently chosen to allow more flexible rules on decommissioning, rights of way, and plant operation outside the rigid framework of lease law. For details on lease levels, escalation clauses, and market norms see Land lease. Either way, the contract should cover rights of way (access for construction and maintenance), a decommissioning obligation with security deposit, and transferability to a project company — the latter is standard, since developers usually operate the site through a special-purpose vehicle (SPV).

Option agreements and preliminary agreements with landowners

During the screening phase, before grid connection and permit feasibility are confirmed, developers typically secure land through option agreements: the owner grants, for a modest annual option fee, the right to conclude a lease or usage agreement within a set period (commonly several years) on terms already negotiated. This reduces the developer's risk (no commitment to land that turns out unsuitable) and gives the owner initial compensation without restricting current use. Only once the option is exercised — typically after a positive grid-connection response and scoping outcome — does the actual lease or usage agreement with higher ongoing payments take effect.

Municipal coordination and urban development agreement

Since ground-mounted PV outside the EEG-eligible area generally requires a municipal development plan (a B-Plan under German building law — Section 35 BauGB only covers privileged special cases), early coordination with the host municipality is its own critical path. Municipalities frequently require an urban development agreement (Section 11 BauGB), which regulates matters such as compensation measures, municipal participation in lease revenue (voluntary, but a common acceptance-building tool), and decommissioning securities. For the planning-law side see Section 35 BauGB. Without a political resolution in principle from the municipal council before detailed planning, developers often end up investing in a site that fails due to local political resistance — which is why municipal coordination belongs before commissioning expert reports, not after.

Contract terms — an assessment

Usage and lease agreements for ground-mounted PV typically run 20 to 30 years in practice, aligned with the plant's service life and the 20-year EEG support period, often with options to extend by a further 5 to 10 years. No sourced, statistically robust average figures exist for the German market as a whole — the ranges given are an assessment from market observation, not a formal survey. What matters for the actual contract drafting is that the term must be long enough to carry the investment (grid connection, plant) economically beyond the EEG support period, in case follow-on marketing via PPA becomes necessary.

Risks of double marketing of sites

Especially on land under high development pressure, it happens that an owner negotiates in parallel with several developers, or offers an already-optioned site to a second interested party. Without land-registry security (see above), the first, purely contractual agreement has no priority over a real right registered later by a third party — this is the central reason for securing an early priority notice. Additional protection comes from contractual-penalty clauses for breach by the owner, and from clarifying ownership (land-registry extract, communities of heirs, usufruct rights) before concluding the option agreement. Where land has multiple co-owners or unresolved inheritance, the risk of a later challenge is especially high and should be reviewed legally before larger investments are made.

Sequence of project development

1. Site screening (map analysis with exclusion layers, ideally GIS-supported).
2. Owner outreach and option/preliminary agreement.
3. Grid-connection enquiry with the responsible grid operator — primarily medium voltage; for large parks also high voltage. The result caps the maximum plant size.
4. Site check with the permitting authority (scoping meeting, clarification of concerns).
5. Commissioning of expert reports (species protection, LBP (landscape conservation accompanying plan), possibly soil report, possibly glare/EIA screening).
6. Building or B-Plan application (Bebauungsplan, local development plan — depending on privileged status).
7. EEG auction or PPA negotiation.
8. Financing (see Financing — analogous to wind, with ground-mounted PV specifics).
9. Construction and commissioning.

Site acquisition — suitability criteria, exclusion layer and project development in 9 steps

Frequently asked questions

What does project development up to the permit cost?

In the order of EUR 50,000–250,000 depending on size and complexity, plus the lease-option payments. If the project fails at an advanced stage, these costs are largely lost — which is why thorough front-loading of the preliminary checks is the single most important risk lever.

Who does this in practice?

Specialised project developers (often regional), in combination with GIS service providers, lawyers and engineering firms. On request, we can make introductions.

From what size does a park become economical at all?

Below 2–3 MWp the fixed-cost hurdle (grid connection, planning, expert reports) becomes tight. In the EEG auction, plants from 5 MWp upwards are typically economically attractive.