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Floating photovoltaics – is floating solar a new trend?

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Floating photovoltaic (FPV) systems, also called floatovoltaics because they float on water, tone down the discussion about land use competition and are technically very advanced. Slightly higher yields, easier installation and opportunities is what outweighs slightly higher system operation costs. 

  

Latest news from the PV market – contradictory signals from Berlin and Brussels

While PV capacities continue to increase worldwide, they are stagnating at a relatively low level in Europe and Germany. Until October 2018, the PV capacities in Germany increased by approx. 2.2 GW, which was thus again close to the target corridor set in the EEG.

 

Currently, however, the adoption of the Act amending the Renewable Energy Sources Act, the Combined Heat and Power Act, the Energy Industry Act and other provisions of energy law (“Collective Energy Act”) in mid December 2018 has strongly worsened the mood in the PV industry. The cuts in incentives for landlord-to-tenant electricity and for building-mounted PV power plants with a capacity of between 40 kWp and 750 kWp are thwarting the trend described above.

 

Positive are however the special auctions and the EU’s Clean Energy for All Europeans package adopted nearly at the same time. The package defines a renewable energy target of 32% for the EU to be reached by 2030.

 

Floating PV as a new trend

Besides the technological trend towards bifacial PV systems, also an increased installation of PV systems on bodies of water has been recently observed. These so-called floating PV power plants are installed on the surface of placid water such as bays or lakes and use floating underwater structures. The PV systems as well as the inverters are anchored to the bottom but it is also possible to connect them to the mainland via floating power lines. Ice formation or temporary drying out of the water do not necessarily rule out an installation.

 

Since 2008 when the first commercial power plant with a capacity of 175 kWp was put into operation in California, the capacities of power plants have increased manifold. In 2016, the first power plant with a capacity of over 10 MWp was commissioned and today, the largest floating PV system has a capacity of 150 MWp. Currently, most of the worldwide installed capacity of 1,100 MWp is in Asia.

 

  

Figure 1: Schematic representation of a floating PV system (Source: Solar Energy Research Institute of Singapore (SERIS) at the National University of Singapore)


Opportunities and challenges

FPV helps eliminate the problem of the land-use competition. It also eliminates the problem of the need for site preparation and in most cases also the problem of the shading of panels, while helping improve energy yield thanks to the cooling effects of water.  The easy scalability of the systems possible due to the even surface of the water basin can help achieve efficiency gains during installation.
The obvious combination of pumped-storage hydroelectric power stations and floating PV plants will enable greater flexibility in the operation of pumped-storage hydroelectric power stations, especially in times of water shortage. In addition, any problems with the volatility of the solar energy generation can be mitigated.

 

Despite the fact that a certain amount of experience is available due to the already installed capacity, there are no long-term studies on the resistance of the components especially in salt water and on the impact of such power plants on the ecosystem. Critical aspects remain also the electrical operational safety, maintenance and repair, and the anchoring system.


Technological potential and economic profitability

Assuming that one percent of the water surface of artificial water basins in Europe is used, the potential for floating PV power plants is 20,000 MWp. Particularly in Germany, the non-permanently flooded conversion areas should also be considered in the medium term, for example abandoned open-pit mining sites.

 

In terms of economic profitability, the installation costs for large-scale Asian projects ranged between 0.7 €/Wp and 1.05 €/Wp in 2018. The resulting higher system and ongoing insurance costs are usually offset with a better performance ratio. Nonetheless, since no significant floating PV capacity has been installed in Germany so far, there are no directly comparable values available yet here1.

Legal framework   

To be able to install floating photovoltaic systems, the legal requirements should be formulated.


Public law framework

The question is whether a development plan and/or a construction permit are also required to the same extent as for land-based installations. Certainly, water law should be taken into account. In particular, the Water Management Act (WHG) and the applicable local water laws form the legal framework here.

 

Installations in, above and below surface waters should be constructed, operated, maintained and decommissioned in such a way that no harmful water pollution can be potentially caused and the maintenance of the water is not made more difficult than what is unavoidable depending on the circumstances. These installations include in particular engineered structures such as buildings, bridges and piers. In addition, local laws apply.

The definition of a power plant under the Water Management Act covers all artificial facilities and structures of certain duration, as well as those perceived as such, which can have significance for water management. The purpose is to counter the potential hazards posed by installations that are located particularly close to bodies of water. This thus includes PV power plants floating on water.

 

In Bavaria, such facilities may only be constructed on bodies of water classed according to the official classification as bodies of water of primary and secondary significance with the approval of the district administration authorities (Bavarian Water Act, BayWG). Legal regulations can extend this permit requirement to include bodies of water of tertiary significance, i.e. usually small basins and streams. As a rule, the obligation to obtain a permit under water law excludes the approval procedure under construction law. In such cases, no construction permit is required.

 

A facility is located in a body of water if it lies within its natural or a defined shoreline. A facility is located on water if it is either less than 60 m from the shoreline or if it can impair the maintenance or the development of the body of water.


Civil law issues   

If a permit under water law is granted, this does not yet mean that the owner agrees to the use of the water surface. Thus, a relevant permit, lease or loan-for-use agreement must be concluded with the owner.

 

In particular, other third-party rights to use the body of water should be taken into account, e.g. fishing rights or shipping rights. For this, if necessary, other agreements should be signed with the authorised parties.


Remuneration for the generated electricity

The electricity generated in the photovoltaic system can be either consumed by the producer or covered by the regime of the Renewable Energy Sources Act (EEG). If the photovoltaic system is to receive remuneration under the EEG, it must fulfil the relevant conditions. Such a photovoltaic system can be installed, for example, on another building structure, on officially approved sites or on conversion areas.

 

In 2014, the Clearingstelle EEG KWKG had to clarify whether electricity generated in a photovoltaic system floating on an excavation lake was eligible for the increased remuneration under EEG 2012 (old version) for conversion areas. The Clearingstelle confirmed that eligibility because, in this specific case, the excavation lake was located on the area of a still active gravel quarry and the ecological pollution of the area caused by the gravel quarry continued at the relevant time as no ecological restoration took place.

Conclusion 

In the future, floating PV systems will be a reasonable as well as technically and economically feasible alternative to "standard" PV systems.
After an economic profitability and technical preliminary analysis, the next step is to determine the framework conditions under public law; in particular, what class of significance a given body of water has been assigned to and whether corresponding special legal regulations apply. These regulations can vary depending on the federal state and the body of water. Depending on the respective business case, it may be necessary to further examine whether a PV power plant is eligible for the EEG remuneration or whether there are any options of direct marketing or consumption. Finally, a user agreement must also be concluded with the respective owner of the body of water.
 
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1 International Bank for Reconstruction and Development / The World Bank, Where Sun Meets Water – Floating Solar Market Report; 2018; Website
accessed on 3.1.2019: http://www.worldbank.org/en/topic/energy/publication/where-sun-meets-water

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