Download Technology Selection - Sunrator Technologies LLP

Designing Solar PV Systems
( Utility Scale)
Module 1 : Solar
Technology Basics
Module 2: Solar Photo Voltaic
Module Technologies
Module 3: Designing Solar PV
Systems (Rooftops)
Module 4: Designing Solar PV Systems
(Utility Scale )
Module 5: Financial Analysis
Module 6: DPR (Detailed
Project Report) & EPC
Module 7: The present Solar
industry scenario and the
future
THE PLANT
Technology
Selection
Layout and Shading
The Plant
Design
Design Optimization
Electrical Design
Technology Selection –
Modules
The following aspects should be kept in
mind while choosing modules:
 High efficiency modules require less land than low
efficiency ones.
 Different spectral response for different technologies.
 Temperature coefficient of power plays an important role
in hot climates.
 Degradation properties should be carefully understood.
 Manufacturer’s warranty period must be looked upon.
 Cost (Rs/Wp), lifetime and maximum system voltage
should be considered.
Technology Selection –
Inverters
 Size plays a very important role for the
inverter connection concept. For utility-scale power
plants, central inverters are preferred.
 High efficiency
 A wide MPP range
 The grid code which affects the inverter sizing and
technology, is required for controlling the reactive power.
Technology Selection –
Inverters (contd.)
 Inverters with high reliability has low downtime including low
maintenance and repair costs.
 For different module specification, string or multi-string
inverters are recommended for minimizing the mismatch
loses.
 For sites with different shading conditions or orientations,
string inverters are more suitable.
 Criteria like plant monitoring, data logging and remote control
must be taken into account.
Technology Selection –
Mounting Structures
A good quality mounting structure, mostly
fabricated from steel or aluminum is expected
to have the following:
• Extensive testing for withstanding the load conditions at the
site.
• Allow field adjustments that may reduce installation time and
compensate for inaccuracies in placement of foundations.
• Thermal expansion using expansion joints where necessary
in long sections for modules not getting unduly stressed.
• Customized structures specific to engineering challenges.
Layout and Shading –
Tilt Angle & Orientation
To generate the maximum energy, the modules
should be tilted at an angle so that the sun hits it
at a perpendicular angle at all times.
Optimum orientation – True South
East orientation-Receive sunlight only before
noon.
West orientation-Receive sunlight only after
noon.
Layout and Shading –
Inter Row Spacing
Image: Schletter Gmbh
 α, the shading limit angle is the solar elevation angle beyond which there is no
inter-row shading on the modules. If the elevation of the sun is lower than α then
a proportion of the module will be shaded. Alongside, there will be an associated
loss in energy yield.
The shading limit angle may be reduced either by reducing the tilt angle β or
increasing the row pitch d.
Electrical Design
DC System – PV array design
• Maximum number of modules in a string
Voc (module) x Nmax < Vmax (Inverter, DC)
• Minimum number of modules in a string
Vmpp (module) x Nmin > Vmpp (Inverter, min)
•Voltage Optimization
• Number of Strings
Electrical Design
DC System – Inverter Sizing
Following factors must be considered when sizing an
inverter:
• The maximum Voc in the coldest daytime temperature
must be less than the inverter maximum DC input voltage.
• The inverter must be able to safely withstand the
maximum array current.
•The minimum Voc in the hottest daytime temperature
must be greater than the inverter DC turn-off voltage.
• The maximum inverter DC current must be greater than
the PV array/s current.
• The inverter MPP range must include PV array MPP
points at different temperatures.
Electrical Design
DC System – Cable Selection and Sizing
Following factors must be considered when sizing
cables:
• The cable voltage rating
• The current carrying capacity of the cable
• The minimization of cable losses
Electrical Design
AC System – AC Cabling
Following factors must be considered when designing the cabling:
• The cable must be rated for the maximum expected voltage.
• The conductor should be able to pass the operating and short circuit
currents safely.
• The conductor should be sized appropriately to ensure that losses
produced by the cable are within acceptable limits.
• The conductors should be sized to avoid voltage drop outside
statutory limits and equipment performance.
• Insulation should be adequate for the environment of installation.
• Either copper or aluminium conductors should be chosen.
• Number of cores (single or multiple) should be chosen accordingly.
• Earthing should be properly designed.
Electrical Design
AC System – AC Switchgear
Considerations must be given to switchgears which are :
• In accordance with IEC and national standards.
• Options for secured off/ earth positions.
• Rated for operational, short circuit currents and correct
operational voltage.
• Remote switching capability for HV switchgear.
• Suitable earthing.
Electrical Design
AC System –
Transformer
selection and
sizing
Transformers are required
for providing suitable
voltage levels for
transmission across the
site and export to the grid.
Transformers can also loose energy through magnetising currents in the core.
These losses are known as iron and cooper losses. Minimising the losses will
increase the energy supplied to the grid and thus enhance the revenue of the
power plant.
Electrical Design
AC System – Substation
Metering: To measure the export of power, tariff
metering is required. The meter provided at the
substation or at the point of connection to the grid has
inputs from the current as well as voltage transformer.
Data Monitoring / SCADA
Auxiliary Equipments: LV power supplies, diesel
generators, lighting, water supplies, drainage, safety
systems etc.
Electrical Design
AC System – Lighting and Surge
protection
• Array frame lighting
• System earthing (DC conductor earthing)
• Inverter earthing
• Lightning and surge protection.
Optimizing the system design
• Reducing the system losses for better plant
performance.
• Balancing annual yield and economic return.
• Proper technology selection and prior simulation
for better analysis and optimization.
• Thorough technical due diligence for mitigating
performance issues.
Thank You!!
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