Floating solar Wikipedia

Introduction

Offshore solar refers to the installation of solar panels on bodies of water in the ocean, ports, bays, or estuaries. Offshore solar installations take two main forms, floating offshore solar and fixed-bottom offshore solar. Floating solar systems support solar panels on floating platforms moored to the seafloor; fixed-bottom solar systems support the panels on a rigid structure resting on the ocean floor. [1] [2] Offshore solar is an emerging alternative to land-based solar power deployments that provides new options for powering coastal communities and facilities with clean energy, especially in large coastal cities and island communities where land availability is severely constrained. This market has accumulated growing interest from major industry stakeholders, namely the National Renewable Energy Laboratory (NREL) found that offshore solar had 40x more energy potential than offshore wind (85 TW vs. 2TW). [NREL-BOEM study] Offshore solar also has promising levelized cost of energy (LCOE) potential with floating solar estimated at $54/MWh ($50 Euro/MWh). [3]

History

Floating Solar has been actively deployed since 2007, when it was first installed in Aichi, Japan, in 2007 by the National Institute of Advanced Industrial Science and Technology.[11][19] Detailed Floating Solar history can be found on the Floating Solar Wikipedia page. Fixed-bottom solar is at an earlier stage of development with an installation planned in the Bohai Sea in China [4] and other models at the concept phase (i.e. RCAM Technologies’ Solar Reef).

Benefits of Offshore Solar

Offshore solar applications (both floating and fixed-bottom) share a few key benefits:

1. Avoidance of Land-Use Conflicts: Offshore or near-shore solar installations can sidestep land-use conflicts, freeing up land for other purposes such as agriculture or development. Offshore solar is a new option for siting near the largest land-load centers such as large cities and ports. [5] [6] [7]
2. Cooling Advantage: Solar panels located near bodies of water can experience a cooling effect, which can increase their efficiency and output by 5–30% compared to land-based systems. [Ayyad A, Golroodbari S, van Sark W. Floating Offshore Photovoltaics across Geographies: An Enhanced Model of Water Cooling. Energies. 2024;17(5):1131.] [Hasan, A. & Dincer, I. A new performance assessment methodology of bifacial photovoltaic solar panels for offshore applications. Energy Conversion and Management 220, 112972 (2020).]
3. Advantageous Integration with Offshore Wind: Offshore solar can be integrated with existing or planned offshore wind developments to increase energy production, reduce storage needs by 70% and cut the levelized cost of energy (LCOE). When deployed together, offshore solar & offshore wind can also share infrastructure, maintenance deployments and supply chain paths, further reducing costs. [8] [9]

These advantages make offshore or floating solar an appealing option for renewable energy generation, particularly in regions where land availability is limited or where there are concerns about land-use conflicts. However, it's also important to consider the challenges associated with floating and fixed-bottom offshore solar systems.

Challenges of Floating Offshore Solar vs. Fixed-Bottom Offshore Solar

A major distinction between these two types of offshore solar are their current levels of technology readiness. Floating offshore solar has 10+ current deployments across Asia and Europe, whereas fixed-bottom solar is a newly emerging concept. Although floating solar has had a longer history, the potential of fixed-bottom offshore solar can be extrapolated from the overriding success of fixed-bottom offshore wind compared to floating offshore wind – this is the guiding principle for its development.

Fixed-bottom structures are easier to install and lack the complications of mooring lines and anchoring. Floating solar arrays can have up to 24x the number of mooring lines as floating offshore wind (10 lines per MW vs 0.4 lines per MW). The biggest concern with this number is mooring line entanglements where large marine mammals can become tangled up in mooring lines or flotsam caught in the mooring lines, resulting in skin abrasions and sometimes drowning. [10] Floating solar is also vulnerable to damage from storms, hurricanes, and ocean disturbances. [11] [12] A key advantage of fixed-bottom offshore solar is its ability to withstand tropical storms, including hurricanes.

Fixed-bottom solar has additional benefits that can be included in the design of its base structure. Historically, fixed bottom structures have functioned as an artificial reef for local wildlife (e.g. offshore oil rigs) which are sometimes left in place and converted into artificial reefs called Rigs-to-Reefs [13] [14]

While floating solar can be installed in much deeper waters due to its flexible mooring and anchoring systems, fixed-bottom structures face challenges due to their large and heavy design, necessitating the use of heavy-lift installation vessels.

Offshore Solar Concepts

There are currently about 10 concepts for offshore solar concepts and they are notably all floating concepts in their demonstration stage.

Floating Solar Concepts

Company/Institution	Concept Name	Country	Unique Design	Current Installations	References
Ocean Sun	N/A	Norway	circular, thin, flexible membrane	N/A
Oceans of Energy	N/A	Netherlands	modular, robust units	(1) Hollandse Kust Noord 1, (2) North Sea 1, (3) North Sea 2, (4) North Sea 3
Fred. Olsen 1848	BRIZO	Norway	pre-tensioned rope mesh	Demonstration in Risør, Norway
Moss Maritime	XolarSurf	Norway	pontoons, flexible steel frame with pretensioned fibre ropes	N/A
Bluewater	N/A	Netherlands	flexible floating units with flexible solar panels	Lake of Oostvoorne
Solar Duck	N/A	Netherlands	Flexibly interconnected semi-sub triangular structures	Merganser
CIMC Raffles	N/A	China	semi-submersible platform	400 kWp in Guangdong, China
BlueNewables	N/A	Spain	tubular steel frame	N/A
SeaVolt	N/A	Belgium	modular steel pontoons	Port of Ostend, Belgium
Universidad de Oviedo	HelioSea	Spain	dual-axis solar tracker, TLP platform	N/A