Utility Scale Segment
for PV applications
White Paper: Floating Solar Installations
Solar energy has been traditionally set to be installed either on large land extensions
or on building rooftops. Since approximately 2010 new spaces have become a solid
option when it comes to installation of solar panels: water.
Ponds, lakes, reservoirs have recently been considered as a suitable location to
deploy solar energy particularly in those countries where land is a scarce resource,
high density of population makes cost of opportunity of using a piece of land
extremely high or there is not suitable land for traditional type of utility scale solar
plants.
Floating installations consists normally on a set of solar panels mounted on fix tilt
metal structure which is mounted on floating bodies (self-buoyant) which are placed
either in salty or sweet water surfaces. These floating platforms can be anchored to
the bottom of the reservoirs, lakes or directly to the nearest shore. These anchors
allow the floating plant to be fixed in a certain location enabling enough flexibility and
play to adjust its position with the eater movement, waves (if apply) or tides.
DC current of the mentioned panels is usually transported through underwater wires
to the nearest shore where the inverters are located (applicable to central inverter
configurations). If the floating solar plant uses string inverters, these are located next
to the array on the floating structure or pontoons. From inverters electricity goes
through transformer to usually step up its voltage. Finally using a transmission or
distribution line the energy is injected to the grid or it is directly feeding a
consumption center (loads)
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Utility Scale Segment
for PV applications
Floating solar plants have some advantages over the ground mounted ones like:
• Using the already existing transmission infrastructures when installed near by
the hydropower plants,
• Better yields due to the cooling effect of the water and lower impact of soiling to
the panels
• Proximity to demand centers and as mentioned before the opportunity of using
areas which were usually idle. Advantages in yield may vary depending on numerous
factors but as studied so far these advantages overcome the increase of capital
expenditures (CAPEX) of this type of solar installations.
• Reduce the evaporation of water of the reservoirs, specially interesting in areas
where water is used for agricultural purposes, water supply to civil population or any
case where sweet water is a limited resource.
• Reduced or also zero expenditures on civil works, land leveling which in some
case could have large environmental impact.
With the rapid growth of solar PV industry in general new applications have arisen.
Floating installation began to be installed in early 2008 with some pilot project but is
has not been until 2016 when the yearly capacity installed surpassed the 100MWp
worldwide. Nowadays, floating installation are still emerging compared to ground
mounted solar PV but its growth is exponential main leveraged with the continuous
decrease of cost of solar panels, inverters and rest of BOS (Balance of system).
Floating installations larger than 1MWp started to be installed later 2013 beginning of
2014 particularly in Japan and Korea where land is a valuable asset for real state
development. Multi-Mega Watt solar plants (>50MWp) became reality in China in
early 2018 being at this point in time, leader not only ground mounted solar plants
but also in floating installation.
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Utility Scale Segment
for PV applications
Most of installations done and those under development are on sweet water mainly
due to the easiness and fewer technical challenges compared to salt water locations
(corrosion, dynamic forces on the pontoons, environmental conditions...). Although
sea floating solar plants in costal/sea areas pose additional complexities are
becoming more popular particularly for insular territories where inland terrain
cannot or is not desirable to be use for solar purposes. Major challenges for coastal
or sea floating PV power include but are not limited to:
• Higher dynamic load on pontoons mainly due to waves, tides and winds which
turn onto a higher resistant mounting and floating structure capable of withstanding
these loads for long periods of time (lifetime of solar plants tends to be around 20
years)
• Anchoring of floating devices/pontoons also needs higher requirements in terms
of mechanical and dynamic resistance. Additional difficulty may appear when
anchors need to be underwater at a certain depth.
• Salt spray is present in the air leading to a harsh corrosion environment affecting
the durability of all component of the solar site particularly metal parts.
• Interaction between animals and marine organism which could interfere in the
functionality of the entire system
• O& M costs tend to be in marine application than in sweet water application
mainly due to higher failure rate in salted environments and need for more
preventive maintenance activities.
The largest uncertainties of marine floating applications are long-term costs, site
performance and durability of materials and components.
In terms of policy and special regulation it is important to mention that floating solar
plants either in sweet or salt water are still raw compared to ground mount systems.
Most of process are similar or the same as the traditional utility scale site but some
challenges are encountered when obtaining environmental permits and clearances,
rights of usage of the water or prices for “water leases”. Floating solar plants may not
need any additional incentives as FIT (Feed in Tarifs), auctions, tenders or any other
mechanisms but it is certain that initial project may carry some additional cost due to
“technology risks” or new specific products for such application which may decrease
their costs when floating becomes mainstream or more adopted.
Market opportunities seem to be limitless due to the amount of available water in
planet. However, floating solar potential is not only determined by the available space
but also by energy needs in the future as well as for the market share floating would
be able to capture competing with other technologies and locations. Nonetheless, if
we assume that between 1% to 10% of the available water bodies for floating solar
are covered it would be possible to determine, at least a range of its potential.
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Utility Scale Segment
for PV applications
Based on the “floating solar market report” from Central bank of development and
Global Solar Atlas © World Bank Group (2019) and the Grand database, © Global
Water System Project (2011) the following table presents some interesting figures on
how to asses the real potential for the next year of Floating PV generation.
This table assumes an average yield (kWh/kWp) for all installation a given GCRThis
table assumes an average yield (kWh/kWp) for all installation a given GCR (Ground
Cover Ratio) or WTC (water cover ratio), variable which may vary widely depending on
location and site. In any case, as an estimate, the afore above table provides an
accurate enough insight on what the potential of applications could be.
Cost of floating solar power plants are slightly higher when looking at its initial
investment compared to its similar site and size on ground. The higher costs mainly
are due to the floating platform (compared to rammed profiles to the soil), anchoring
element of the pontoons (not needed for ground mount installations) and higher
technical requirement of some components due to high humidity and corrosion. ON
top of this, if the floating installation if located in coastal areas, additional costs need
to be added due to higher specifications of components.
Capital expenditures of a floating system range between 0.8$ to 1.3$ per watt peak
including solar plant plus transformer and transmission up to tapping point. Although
these numbers are tentative, they may vary depending on the location of the project,
floating bodies used, depth of its anchoring mechanism and size of the entire system.
Floating systems as well as ground mounted one benefit from economies of scale. At
the moment floating installation have similar costs to the rooftop installations at a
given size or installed power.
The chart below provided by the Word bank Floating report shows the capital
expenses of a floating system depending on regions and sizes.
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Utility Scale Segment
for PV applications
What is very interesting to analyze is that whereas the initial investment for utility
scale floating system is higher than his homolog on ground how the final LCOE
(levelized cost of electricity) would compare considered the higher yield of floating
systems. The expected increase of Yield or PR (performance ratio) is between 5% to
10% compared land mounted panels. The following table elaborated by SERIS shows
LCOE comparison between the same solar power plant (50MWp) ground mounted
and floating in three different locations/regions.
It can be seen that with and increase of PR of 10% the difference of LCOE between a
given floating installation and a ground mounted one varies between 3. 52% and 3.
53% between different locations at a WACC (Weighted Average Cost of Capital) of 6%
and between 4.52% and 4.21% with a WACC of 10%.
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Utility Scale Segment
for PV applications
The difference is not significant particularly at the stage where floating PV systems
seem to be in their embryony phase. It seems logical even that with the further
adoption of floating system its CAPEX could even go further down and become
cheaper than ground-mounted systems. Moreover, assuming that water surface in
some regions could become even cheaper than developable soil, floating PV systems
could even become in the mid term even more attractive than the traditional utility
scale solar plants.
Solar floating applications seem to accelerate as solar industry does the same and as
technology matures. These types of solar plant provide a new landscape for
renewable energies which would enable energy mix of the certain countries to be
cleaner and with lower environmental impact while benefiting from idle surface.
Reduction of land which could be used for real state development or agricultural use
is the major strength of floating solar.
When all these benefits are combined with an incremental production yield of 5% to
10% compared to ground mounted system, LCOE for floating systems matches values
close to soil-use solar plants and wind. This fact makes floating more attractive
particularly considered that floating applications are in a very early stage of their
deployment.
Costs for floating plants are decreasing and the it is planned the continue to do so in
the next years providing to this type of installation enough benefits to gain an
important share in the global energy mix.
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