This document analyzes different solar energy storage systems. It discusses electrical storage methods like pumped hydroelectric storage, compressed air energy storage, flywheels, batteries and capacitors. Thermal storage methods explored are sensible heat, latent heat and sorption. The document compares the systems based on cost, performance, process, impact, maturity and requirements. It recommends pumped hydroelectric storage, battery storage, latent heat storage and sensible heat storage as suitable for Sri Lanka. Specifically, it suggests upgrading existing hydro power plants to pumped hydro, using batteries for domestic PV systems, and sensible heat for domestic heating to effectively use solar power and reduce national grid usage.

1. Analyzing Solar Energy
Storage Systems
Name: N.S.A.C.A.Senevirathna
UWE No: 15028377

2. Contents
 Introduction
 Solar Power
 Solar Energy Storage
 Aims
 Solar Storage Systems
 Comparative Analysis
 Results
 Recommended Solar Energy Storage
Systems For Sri Lanka

3. Introduction
 Solar Power
 Conversion of energy from sunlight-electricity
 Using
 Photovoltaic (PV)
 Concentrated Solar Power (CSP)
 Energy Storage
Process of storing produced energy
Mechanical, electrical, thermal and chemical storage
Electrical
Thermal
Solar

4. Introduction
PV CS
P
Electrical Thermal

5. Aims
 An analysis on solar storage methods or mechanisms
 Process
 Performance Characteristics
 Advantages and disadvantages
 Commercial maturity
 Cost
 Identifying strengths and weaknesses of each system
 Identifying suitable solar energy storage systems
 Recommending suitable solar energy storage systems for Sri
Lanka

6. Electrical Energy Storage
Systems
PHS CAES SMES Flywheel Capacitors Battery
Thermal Energy
Storage
Systems
Sensible Heat Latent Heat Sorption

7. Electrical Energy
Storage Systems

8. Pumped Hydroelectric
Storage
 Using the excess electrical energy generated at off peak hours to
pump water from a lower reservoir to a higher reservoir
 Use the stored water to generate hydropower
► Performance Facts:
 Efficiency 60-90%
 Energy density 30Wh/kg
 Cycle life of 20-50 years

9. Pumped Hydroelectric Storage
 Advantages:
 Stores a large volume of potential energy
 High Efficiency
 Ability to regain used water
 Low cost per unit (around 10$/kWh)
 No pollution
 Disadvantages:
 Scarcity of available sites
 Long lead time and high construction cost
 Environmental Impact

10. Compressed Air Energy
Storage
 Use the off peak excess electricity to compress air
 Use the compressed air as fuel to generate electricity
► Performance Facts:
 Efficiency 40-50%
 Low self-discharge
 Higher energy density than PHS
 Life cycle 20-50 years

11. Compressed Air Energy
Storage
 Advantages
 Conserves natural gas
 Ancillary services to the grid (peak shaving, spinning reserve, VAR support
and arbitrage)
 Disadvantages
 Low round-trip efficiency
 Safety issues
 Site requirements
 Air pollution

12. Flywheel Energy Storage
 Stores energy in the form of angular momentum
 At charge acts as a motor
 At discharge acts as a generator
 Performance Facts:
 Energy density range from 20-1500Wh/kg
 Cycling capacity up to 90 000
charge-discharge cycles
 Lifetime over 20 years

13. Flywheel Energy Storage
► Advantages:
 Environmental friendly
 Fast Response Time
 Disadvantages:
 Safety risks
 Low duration of energy storage
 Bearings wearing off quickly

14. Superconducting Magnetic
Energy Storage
 Stores electrical energy in magnetic field generated by direct
current
 Includes: Superconducting coil, power conditioning system,
cryogenic system and control unit
 Performance Facts:
 High cycling capability
 Round-trip efficiency about
97‐98%
 Capacity depends on the
application

15. Superconducting Magnetic
Energy Storage
 Advantages:
 Fast response
 High cycling efficiency
 Safety
 No pollution
 Low site requirements
 Disadvantages:
 Land/area requirement
 High power requirement
 Magnetic field Impact
 Complexity and cost

16. Battery Energy Storage
 Electrical energy is stored as chemical energy
BES
Flow
Secondary
Lead acid
battery
Sodium
sulfur battery
Nickel-based
battery
Lithium-ion
battery

17. Battery Energy Storage
► Advantages:
 High efficiency
 Low cost
 Ease of installation
 High Reliability
► Disadvantages:
 Low cycle life
 Safety
 Environmental impact

18. Super-capacitor Energy
Storage
 Passive two terminal electrical component
 Stores electrical energy in an electric field
 Performance Facts:
 Around half million life cycles
 Energy density up to 5.12 kW/kg
 Efficiency range from 75% to 95%

19. Super-capacitor Energy
Storage
 Advantages:
 High specific power
 Very high cycle life
 Low environmental impact
 High efficiency
 Disadvantages:
 High cost per watt
 Low specific energy and high self discharge in comparison to
batteries
 Linear discharge voltage prevents using the full energy spectrum
 Low cell voltage

20. Thermal Energy
Storage Systems

21. Sensible Heat Energy
Storage
 Storing heat energy in liquid/solid material
 Use CSP technology
 Example: solar water and air heaters, graphite and concrete storage
 Performance Facts:
 Depends on the storage material
 Storage capacity ranging from 10-50 kWh/t
 Efficiency 50-90%

22. Sensible Heat Energy
Storage
 Advantages:
 Low cost
 Relatively high specific heat
 Simple process
►Disadvantages:
 Heat loss
 Short storage duration
 Low energy density

23. Latent Heat Storage
 Energy storage in phase changing material
 organic (paraffin, fatty acids)
 Inorganic (hydrates, molten salts, metal)
 Eutectic (organic‐organic, organic‐inorganic, inorganic‐inorganic
compounds)
 Performance Facts:
 Efficiencies 75-90%
 Energy densities100 kWh/m3

24. Latent Heat Storage

25. Latent Heat Storage
 Advantages:
 Higher energy densities
 Relatively long storage duration
►Disadvantages:
 long storage duration
 Higher cost
 Complex process

26. Sorption Storage
 Fixation or capture of a gas or a vapor (sorbate) by a solid or liquid
substance (sorbent)
 AB + Heat = Sorbate A + Sorbent B
 Energy is stored in A and B compounds
 Performance Facts:
 Storage capacities of up to 250 kWh/t
 Efficiency from 75% -100%
 Operation temperatures over 300°C

27. Sorption
 Advantages:
 Low heat loss
 Long-term energy storage
 High energy densities (in comparison to sensible and latent heat storage)
 Disadvantages:
 High cost
 Complex process
 Environmental impact
 Safety issues

28. Comparative Analysis
System Cost Performance Process Impact Maturity Requirements
PHS
- + + - + -
Flywheel
- - - + - +
CAES
- + - - + -
SMES
- + + - - +
Battery
+ + + - + -
Capacitors
- + + - + +
►Electrical Storage Systems:-
Positive (+)
Negative (-)

29. Comparative Analysis
 Thermal Storage Systems:
 Positive (+)
 Negative (-)
System Cost Performance Process Impact Maturity Requirements
Sensible
heat
+ - + + + +
Latent heat
+ + + - + -
Sorption
- + - - - -

30. Conclusion : Suitable Solar Energy
Storage Methods
 Electrical energy storage systems
 PHS
 Battery storage
 Thermal energy storage systems
 Latent heat storage
 Sensible heat storage

31. Solar Potential in Sri Lanka

32. Why Solar Energy Storage
Systems For Sri Lanka
 Use solar power effectively
 Reduce electricity usage from the national grid
 Save capital and energy
 Balance the electrical power supply and demand

33. Recommended Solar Energy
Storage Systems For Sri Lanka
 Pumped Hydroelectric Storage:-
Upgrade existing hydro power plants in to PHS plants
Construction of PHS plants at
new sites
 Contribute power to the
national grid

34. Recommended Solar Energy
Storage Systems For Sri Lanka
 Battery Energy Storage:-
 For domestic PV systems
 Will reduce the use of power from the national grid
during the evening period

36. Recommended Solar Energy
Storage Systems For Sri Lanka
 Sensible Heat Energy Storage:-
 For domestic heating purposes:
• solar water and air heaters
 Save electrical power

37. Questions

38. Thank You