Environmental Impact Assessment for Floating Solar: the Typical Process, Timeline, and Cost in Europe

Introduction

Every floating solar (FPV) project on a water body sits inside a permitting envelope, and for many sites its central piece is the environmental impact assessment (EIA). Where a rooftop system usually needs little more than a building permit, a project on a lake, reservoir, industrial basin, or nearshore water interacts with aquatic habitats, water quality, birds, and navigation — so the EIA is how developers show these effects have been identified and managed before a consent is granted. It is also the part of the schedule most often underestimated. Across the EU the process follows a common logic, and this article walks through it: the typical steps, what drives the timeline, and what it costs.

One directive, national procedures

The process is set by the EIA Directive (2011/92/EU, as amended by 2014/52/EU), which each Member State writes into its own law. The authorities and procedure names differ by country, but the sequence — and what the assessment must cover — is recognisable everywhere.

The directive splits projects in two. Annex I projects always need a full EIA; most renewables, floating solar included, fall under Annex II, where the authority decides through a screening step (national thresholds, or a case-by-case check against the directive’s criteria of size, location, and sensitivity). A modest FPV plant on a low-sensitivity basin may be screened out; the same capacity beside a protected estuary may be screened in.

The typical process, step by step

Screening. The authority decides whether a full EIA is required, in principle within 90 days of receiving complete information. A screened-out project proceeds without a full assessment; a screened-in one starts the EIA proper.

Scoping. Scoping sets what will be studied in depth, what can be handled by desk review, and over what area. A formal scoping opinion, where requested, locks the scope before survey budgets are committed — and applies the proportionality principle, so effort tracks how large and how sensitive the site actually is rather than over-studying low-risk topics.

Baseline and field surveys. The baseline captures the state of the environment before the project — water quality and sediments, benthic habitats (in the sea, features like seagrass or maerl beds), fish, birds and bats, and human uses such as navigation and fishing. Some topics need seasonal fieldwork; others rely on existing data. This is usually the critical path, because ecological surveys can only run in certain windows of the year.

EIA report and mitigation. The findings become the EIA report (Annex IV of the directive): baseline, direct and indirect effects, reasonable alternatives, and the mitigation hierarchy — avoid, reduce, then compensate for what remains. For FPV, mitigation often shapes the layout, the anchoring concept, and the construction calendar.

Consultation and decision. The report is published for public and expert comment (at least 30 days under the directive), after which the authority issues a reasoned decision — the consent — explaining how those inputs were weighed.

The EIA rarely travels alone. It usually anchors a wider authorisation that also covers water-use rights, occupation of public maritime or lake domain, and — where a protected site could be affected — an appropriate assessment under the Habitats Directive. In France, for instance, HelioRec’s projects fold the EIA, a separate water-law file, and a maritime occupation permit into one coordinated authorisation.

Timeline: what actually drives it

The biggest driver of the timeline isn’t the paperwork — it’s the seasonal survey calendar. Bird counts and benthic campaigns each have their window, and missing one can cost a year, so starting surveys early matters more than compressing the write-up.

For a marine or nearshore FPV project needing a full assessment, the preparation phases run roughly:

• Scoping: about 1–2 months.

• Baseline studies: typically 6–12 months, often in parallel with other work — and the main variable in the schedule.

• Reporting: about 3–4 months.

That brings the file to the point of submission in roughly 9–12 months. What’s usually underestimated is what follows: authority review, public consultation, and the decision add several more months, so a realistic span from kick-off to a granted consent is around 18–24 months — before any extension for survey seasons or extra requests. The lever isn’t plant size but how cleanly the baseline is planned from the start.

Figure. Indicative stages and durations of the EIA process for a marine or nearshore floating solar project in Europe. Preparing the file for submission typically takes 9–12 months; the review, consultation, and decision that follow bring the realistic total to around 18–24 months.

Cost: a small fraction of project value, but front-loaded

EIA cost tracks how much specialist survey work a site needs. As a benchmark, a European Commission study put EIA costs between roughly 0.01% and 2.5% of total project cost, averaging about 0.5%, with most below that.

For FPV the drivers are the field surveys — benthic inspections, water and sediment sampling, multi-season bird and bat work — while desk topics and reporting are more predictable. Because much of the survey effort is fixed regardless of size, the per-kWp cost falls as projects get larger.

What is specific to floating solar — and where design helps

Two things set FPV apart from a land-based EIA. First, the receiving environment is aquatic: benthic habitats, water and sediment quality move to the centre, alongside topics rarely seen on land — glare on navigation and nearby aviation, non-indigenous species on artificial floating substrates, and how birds use the structures. Second, the impact profile depends heavily on how the array is anchored and installed.

That second point is where design feeds straight into permitting scope. A reversible, low-disturbance setup — gravity anchors rather than pile driving, and no dredging — removes several of the more sensitive angles around seabed disturbance and contaminated sediment, and supports a lighter, proportionate assessment. HelioRec’s marine-grade platforms are built this way, keeping the footprint — and the assessment it triggers — proportionate to the project.

Practical checklist

Before you start:

• Annex I or Annex II in the country concerned — and are there protected sites nearby that could trigger an appropriate assessment?

• Which parallel consents (water-use rights, domain occupation) run alongside the EIA?

Planning the assessment:

• Have you mapped the seasonal survey windows and protected them in the schedule?

• Have you requested a scoping opinion to fix scope before committing survey budgets?

Scope and cost:

• Does the anchoring method minimise seabed disturbance and avoid dredging?

• Are alternatives and the mitigation hierarchy documented from the design stage, not reconstructed at the end?

FAQs

Does every floating solar project need a full EIA?

No — most fall under Annex II, where screening decides. Low-sensitivity sites are often screened out; those near protected or ecologically rich areas usually aren’t, regardless of size.

How long does it take?

Preparing the file takes about 9–12 months for a full assessment with seasonal baseline data; review, consultation, and decision bring the realistic total to around 18–24 months. The survey calendar sets the pace.

How much does it cost?

Mostly a function of survey work. A European Commission benchmark puts the average near 0.5% of project cost, with most below — though the fixed effort makes the relative cost higher on smaller plants.

Can design reduce the burden?

Yes. A reversible, low-disturbance design — gravity anchors, no dredging — removes several sensitive angles and supports a proportionate scope. Early site selection and stakeholder engagement matter as much as the technology.

HelioRec designs, manufactures, and deploys floating solar systems for both inland and marine nearshore environments. To discuss whether floating solar is suited to your site, *contact us