Floating Solar PPT IIT Rorkee

Indian Institute of Technology Roorkee
Department of Hydro and Renewable Energy

Ruby Jubilee Lecture Series July 2021
An overview of the
floating solar industry
21th July 2021

Marine Bernicot (bernicot@isl.fr)
Agenda
1. Context
2. Energy generation
3. Design & Challenges
4. E&S aspects
1. Context
The floating PV sector
Recent developments
Floating PV projects to come
• For the next 3 years
• In 5 – 10 years ~20 to 40 GW, mainly in Asia

2. Energy & Profitability
Why FPV instead of ground mounted ?
• 15% more expensive

• “New” technology → risks
Key benefits of FPV

• Improved cooling effect
• Reduce evaporation
• Avoid land acquisition
Almost equivalent LCOE ?

~ 4 to 7 cUS$/kWh
/!\ not all sites are similar : irradiation, temperature, depth,

waves, connection point…
Energy yields
Altao Rabagaõ, Portugal
• 220 kW, 2016
Energy yields
Lac des Toules, Switzerland
• Bifacial panels, pilot
Equivalent to a PV plant
in North Algeria !
An opportunity: hybridizing
A hydro A solar EMS A Solar-Hydro PP

+
reservoir powerplant
GWh/y
GWh/y
GWh/y
Dispatchable energy Dispatchable energy

Total energy Total energy
Complementarity – Time scales
Further opportunities
• Increase firm capacity without additional use of water
• Save water during dry season
• Increase HYDRO production (displacing Hydro production from Dry season to Wet
season → increased average reservoir water level → increased power per m³ turbined)
EXAMPLE : MANANTALI, 205 MW / 840 GWh/yr Hydro

Yearly energy Guaranted power at night peak demand
With 70 MWAC solar → 992 GWh 114 MW
- Present
Reservoir Water level (m)
- HydroSolar with 70 MWAC solar
Date (from 01 January to 31 December)

In a win-win mode
Save water
PV
Penetretion Co-
rate Firm injection
capacity
But hybridization also brings constraints…

Competitive
• Quick variation of downstream flow → E&S impacts storage
solution
• Hydro equipment fatigue
• Can compete with other existing uses of the reservoir
• Can lead to loss of power if not managed properly
• Complexify the operation: prediction & communication
between hydro & PV
EMS is the key
… And the balance is not trivial
• Depending on the specific constraints of each dam
• Probably easier if only one unique PV / hydro operator
3. Design & Challenges
Anchors design
Floats design
OceanSun,
Banja reservoir, Albania
Input data for design
+ seisms, floating debris, possibilitis of grounding…
→ Drives the choice and design of floats and anchorage system
/!\ Very site dependant ! ponds, quarry lakes, dam reservoirs,

lagoon, ocean….
Floating PV: Main loads
Wind
10 - 50 m/s
Current
(in most cases - including
extreme events - few
cm/s because of the
@ SolarDock reservoir)
Waves
(Due to wind) + others depending on specific cases
→ Wind generates most of the loads on the floating structure

→ For a given wind, loads can be given by litterature (Maruo, Eurocode,…)
→ Loads allow sizing and numbers of Anchors
How to choose the wind / natural event intensity ?

Risk analysis
Floating PV on other dam bodies Floating PV on dam reservoirs
In case of anchors / structure failure: In case of anchors / structure failure:
➢ Production breakdown ➢ Production breakdown / Loss of capital
➢ Loss of capital ➢ Possible obstruction of spillway
➢ Possible additional loads on structures

« What is the risk of loosing my investment ➢ Possible breach of upstream dam impermeability
on the life time of the FPV? »
➢ Possible Fire
→ T = 50 - 100 years ➢ Possible dam failure

(Eurocode, industry reference)
« What is the risk in terms of safety? »
→ ICOLD, CFBR :
Probability ~ 10-3 / 10-5

T = 1000 - 100 000 years
FPV on dam reservoirs is (more) challenging
One objective : meet the required safety criterias
10-3 / 10-5 residual risk for the dam → licensing
Option 1: reduce the FPV failure probability

By strengthening the design criterias → expensive and not easy
By reducing the loads → shape of the island, drag coefficient, exposition to floating debris
Option 2: Disconnect FPV safety requirements from dam safety requirements

By evaluating the sensitivity of the dam→ wind direction, size of the island, spillway sensitive to obstruction ?
By adding safety barriers in case of FPV failure→ log boom or jam protection
Today : no existing consensus on

which option to consider //
Administrations are also learning…
4. E&S Aspects
Physical environment
But also…
• An opportunity to mitigate effects of
climate change on water bodies
Biological environment
• Reduction of bank erosion thanks to less

wind and current
Social environment
• Tourism
• Quick variations of downstream flow
Fisheries in Cirata reservoir, Indonesia
(hybridization)
Land use and CO2
• Reduces land use pressure

• Low CO2 emission
• Solar hydro Hybridization enhances those gains:
• More kW and kWh / km² → decreased global footprint
• Less CO2 / kW & kWh by making a better use of the land
Mitigation
• % of coverage
• elevated modules to allow air circulation
• glass-glass solar panels to ensure the light still reaches the water,
• ‘bio hut cages’ to feed fishes and vertebrates
• …
• Very case dependent !
But still, We lack data and lessons from case-studies to support EIA
(Env. Impact Assessments)
→ MONITORING !
Sum up: benefits and challenges
References
• ESMAP “Where Sun meets Water, Floating Solar Market Report” 2019
https://openknowledge.worldbank.org/bitstream/handle/10986/31880/Floating-Solar-Market-
Report.pdf?sequence=1&isAllowed=y
• ESMAP “Where Sun meets Water, Floating Solar Handbook for Practitioners” 2019
https://documents1.worldbank.org/curated/en/418961572293438109/pdf/Where-Sun-Meets-Water-
Floating-Solar-Handbook-for-Practitioners.pdf
• ELSEVIER “Floating PV Plants” 2020

https://www.elsevier.com/books/floating-pv-plants/rosa-clot/978-0-12-817061-8
• DNV, “Design, development and operation of floating solar photovoltaic systems, Recommended
practice”, Report DNVGL-RP-0584, 2021 https://rules.dnv.com/docs/pdf/DNV/RP/2021-03/DNVGL-
RP-0584.pdf
• https://www.sciencedirect.com/science/article/pii/S0038092X2100116X
+ Contributions from L. Deroo (ISL), World Bank, SERIS…

And all participants of the Solar Hydro 2021 event !
Thank you !
Any questions ?

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Indian Institute of Technology Roorkee

Department of Hydro and Renewable Energy

21th July 2021

• In 5 – 10 years ~20 to 40 GW, mainly in Asia

• 15% more expensive

Key benefits of FPV

Almost equivalent LCOE ?

/!\ not all sites are similar : irradiation, temperature, depth,

A hydro A solar EMS A Solar-Hydro PP

Dispatchable energy Dispatchable energy

EXAMPLE : MANANTALI, 205 MW / 840 GWh/yr Hydro

- HydroSolar with 70 MWAC solar

Date (from 01 January to 31 December)

But hybridization also brings constraints…

+ seisms, floating debris, possibilitis of grounding…

→ Drives the choice and design of floats and anchorage system

/!\ Very site dependant ! ponds, quarry lakes, dam reservoirs,

→ Wind generates most of the loads on the floating structure

How to choose the wind / natural event intensity ?

In case of anchors / structure failure: In case of anchors / structure failure:

➢ Production breakdown ➢ Production breakdown / Loss of capital

➢ Loss of capital ➢ Possible obstruction of spillway

➢ Possible additional loads on structures

→ T = 50 - 100 years ➢ Possible dam failure

Probability ~ 10-3 / 10-5

Option 1: reduce the FPV failure probability

Option 2: Disconnect FPV safety requirements from dam safety requirements

Today : no existing consensus on

• Reduction of bank erosion thanks to less

• Reduces land use pressure

• ELSEVIER “Floating PV Plants” 2020

+ Contributions from L. Deroo (ISL), World Bank, SERIS…

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