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Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
Content:
Sr. No.
Description
Page No
A
Introduction
1
B
Salient Stipulations in MERC Reg. 2015
1
C
Codes and Standards
2
D
E
F
IEEE 519 Harmonic Standards and IEC 61000-3-3
Flicker Standards
Technical requirement of the Grid Connected Roof Top
Solar
Equipment Features
3
3
6
i
Solar PV modules and array
6
ii
Module mounting structure
7
iii
Power Conditioning Unit/Inverter
7
iv
ACDB (LT Panel)
8
v
DC & AC Switches
8
vi
Cables and installation accessories
8
vii
Earthing and lightning protection
8
G
Preliminary Site Visit Check List
9
H
Pre Commissioning Check List
9
I
Safety
9
Annexure – 1: SLD for < 8 kW , single-phase
12
Annexure – 2: SLD for > 8 kW but < 150 kW, 3-phase
13
Annexure – 3: SLD for > 150 kW , 3-phase
15
Annexure – 4: Preliminary Survey Check-Sheet
16
Annexure – 5: Commissioning Check-Sheet
17
Annexure – 6: Dimensions of equipment
17
Annexure---7: Sample Documents
20
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
List of Tables
Sr. No.
Description
Page No
1
Codes and Standards
2
2
Harmonic Voltage Distortion Limits in Percent of Nominal
Fundamental Frequency Voltage ( IEEE Standard 5191992, table 11.1)
2
3
Basis for Harmonic Current Limits
2
4
Harmonic Current Distortion limits (Ih) in percent of IL
2
5
Flicker standard IEC 61000-3-3
3
6
Grid Connectivity technical requirement
Technical Guidelines for Grid Tied Distributed Generation (Solar)
3-6
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CES Department
List of Figures
Sr. No.
Description
Page No
1
Standard Shutdown Procedure Signage content
10
2
Specification on the Meter Cabin
11
3
Signage on/near the components in the meter cabin
11
4
Signage near Inverter
11
A.1
A.2
A.3
Typical SLD of grid Connected Roof Top PV with
capacity below 8kW
Typical SLD for grid Connected Roof Top PV with
capacity above 8kW and below 150kW
Typical SLD grid Connected Roof Top PV with capacity
above 150kW
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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13
15
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CES Department
A. Introduction
The depleting sources of fossil fuels, sharp increase in power tariffs to industrialists due to heavy
subsidies to Agriculture, very high T&D losses, decrease in reliability of power required, leads one to
think of the alternative soco-economic, efficient, environment friendly and reliable sources of energies.
The Power crises in Maharashtra is increasing day by day with a peak demand shortfall of 2000 MW.
Maharashtra is having a total installed capacity of 15085 MW (including Central sector share) of
centralized power plants and 623 MW of decentralized non-conventional power plants. Still there is a
large potential in the non-conventional energy sources sector which can be tapped. This distributed
potential can be harnessed to meet increasing power demand and to improve the techno-economic
scenario.
Setting up of large solar power projects requires huge land space whereas availability of land is a
major constraint in Mumbai city limits. The prevailing scenario of declining trend in solar prices and
increasing retail power tariff across most consumer categories like residential, commercial and
industrial consumers would encourage consumers to install roof top solar systems. . Therefore, roof
top solar is set to witness appreciable scaling of capacities in Mumbai. With the new regulation (Net
Metering for Roof-top Solar PV Systems Regulations 2015) issued by MERC, RInfra has decided to
issue Technical policy document for NET-metering and LT connectivity.
B. Salient Stipulations in MERC (Net Metering for Roof-top Solar PV Systems) Regulations,
2015 – at a Glance
1. Shall be permitted on “first come first serve” basis (Cl. 3.1)
2. Cumulative Capacity of all Roof-top Solar PV (RT-SPV) Systems under Net Metering
connected to a particular DT of RInfra shall not exceed 40 % of its Capacity (Cl.4.1)
3. RInfra shall provide information on Website regarding Solar capacity available against each DT
within 3 months of this notification (Cl. 4.2)
4. Roof-top Solar PV System Capacity shall not exceed the Consumer’s Contract Demand (in
kVA) or Sanctioned Load (in kW) (Cl. 5.1)
5. AC Voltage level of Solar Injection shall be as below: (Cl. 5.2)
a. 230 / 240 V (single-phase) -------------------- for capacity less than 8 kW / 40 Amp
b. 400 / 415 V (three-phase) -------------------- for cap. less than 150 kW /187 kVA
c. 11 kV and above --------------------------------- for cap. above 150 kW / 187 kVA
6. HT (11 kV & above) Consumers may inject at LT Bus-bar, provided that Net Meter is installed
on the HT side of Transformer.(Cl.5.4)
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
7. Consumer may install RT-SPV with or without Battery back-up provided that if battery is
present, separate back-up wiring to prevent the battery Power from flowing into the RInfra Grid
in absence of Grid supply. (Cl.6.2)
8. Consumer shall provide adequate protection for Islanding the RT-SPV from RInfra Network in
the event of grid supply failure (Cl.6.4)
9. RInfra shall ensure that the inter-connection of the RT-SPV System with it’s Network conforms
to Specifications , Standards and other provisions specified in the CEA (Technical Standard for
Connectivity of the Distributed Generation Resources) Regulations, 2013, the CEA (Measures
Relating to Safety & Electric Supply) Regulations 2010 and the MERC (State Grid Code)
Regulations 2006 or as may be specified in future.(Cl. 6.1)
10. Metering arrangement shall have Net Meter (procured and installed by RInfra) and also Solar
Generation Meter (procured & installed by Consumer or RInfra, who desires that such energy
be counted towards meeting its RPO) (Cl. 7)
C.
Codes and Standards
The installation shall meet the requirements of Indian Electricity rules, CEA and MERC Guidelines for
grid connectivity. The materials, equipment and methods used in the installation shall conform to the
latest edition of IS and IEC standards, and other national and international applicable standards
including the following. If standard other than IS/IEC are used in design, manufacturing and testing, a
copy of the same in English shall be submitted.
IEEE 929-2000
Recommended Practice for Utility Interface of Photovoltaic (PV) Systems
IEC 61730 Part 1- Requirements for construction & requirements for testing, for safety qualification
2
IEEE 519
Power Quality Standards
IEC 61000
Flicker Standard
IEC 61683
Photovoltaic systems - Power conditioners - Procedure for measuring efficiency
IEC 62093
Balance-of-system components for photovoltaic systems - Design qualification
natural environments
EMC
EN 61000-6-2, EN 61000-6-4, EN 61000-3-11, EN 61000-3-12, EN 50178
IEC 62109-2
Safety of power converters for use in photovoltaic power systems - Part 2:
Particular requirements for inverters
IEC 62116
Test procedure of islanding prevention measures for utility interconnected
photovoltaic inverters
IEC 60269 / IS- Low voltage fuses
13703
IS 15707
Testing, Evaluation, Installation and Maintenance of ac Electricity Meters - Code
of Practice.
IEC 60947
Low Voltage Switchgear and Control-gear
IS 1554
PVC Insulated Cable for working voltages up to and including 1100V
IS 2551
Signage Requirement
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
IS 3043
IEC 62305
IEC 62446
IS 732
CEA -2007
CEA-2013
MERC -2013
Earthing Standards
Lightning Protection
Operation , Maintenance and Documentation
Wiring Rules
Technical Standards for connection to grid 2007 ( amendment 2013)
Technical standard for Connectivity of the Distributed generation resources
regulation 2013
Maharashtra Electricity Regulatory Commission ( Net Metering for Roof Top Solar
Phot0 Voltaic Systems) Regulation 2013
Table 1: Codes and Standards
D. IEEE 519 Harmonic Standards and IEC 61000-3-3 Flicker Standards
Bus Voltage at PCC Vn (kV)
Vn ≤ 69
69 ≤ Vn ≤161
Individual Harmonic
Distortion (%)
2
1.5
Voltage Total Voltage Distortion, THDVn
(%)
5
2.5
Vn > 161
1.0
1.5
Table 2: Harmonic Voltage Distortion Limits in Percent of Nominal Fundamental Frequency Voltage (
IEEE Standard 519-1992, table 11.1)
20
Max
individual
frequency
Related Assumption
voltage harmonic (%)
2.5-3.0
Dedicated system
2-2.5
1-2 Large customer
50
100
1000
1-1.5
0.5-1.0
0.05-0.10
Short Circuit ratio at PCC
10
A few relatively large customer
5-20 medium size customer
Many small customer
Table 3 Basis for Harmonic Current Limits
Isc/IL
h<11
11≤ h ≤17
17≤ h ≤23
23≤ h ≤35
35 ≤h
TDD
<20
20-50
4
7
2
3.5
1.5
2.5
0.6
1
0.3
0.5
5
8
50-100
10
4.5
4
1.5
0.7
12
100-1000
12
5.5
5
2
1
15
>1000
15
7
2.5
1.4
6
Table 4: Harmonic Current Distortion limits (Ih) in percent of IL
20
Note: IL: is fundamental component of the maximum demand load current
Isc: Short circuit current at PCC
Ih: Magnitude of individual harmonic component (rms amps)
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
Value
Pst
(Short
term
"perceptibility" value)
Plt
(Long
term
"perceptibility" value)
flicker
flicker
Observation Interval
Limiting Value
10 min
1.0
2h
0.65
Table 5: Flicker standard IEC 61000-3-3
E. Technical requirement of the Grid Connected Roof Top Solar
Sr.No
3
Parameter
Overall
conditions of
service
Overall Grid
Standards
Equipment
4
Meters
5
Safety and
supply
6
Harmonic
Requirements
Harmonic
Current
1
2
7
8
9
10
11
Reference
Requirement
State Distribution/Supply
Code
Reference to State Distribution Code
CEA Regulation 2010
Reference to regulations
BIS / IEC / IEEE
Central Electricity authority
(Installation & operation of
meters) Regulation 2006
Central Electricity authority
(measure for safety and
electricity supply) Regulation
2010
IEEE 519, CEA (Technical
Standards for Connectivity of
the Distributed Generation
Resources) Regulations 2013
Reference to standards
Reference to regulations and additional
conditions issued by the Commission.
Reference to regulations
Harmonic current Injections from a
generating station shall not exceed the
limits specified in IEEE 519 (indicated in
Section D)
Photovoltaic system must be equipped with
CEA (Technical Standards
a grid frequency synchronization device.
for Connectivity of the
Every time the generating station is
Synchronization Distributed Generation
synchronized to the electricity System, It
Resources) Regulations
shall not cause voltage fluctuation greater
2013
than +/- 5% at point of connection.
The voltage-operating window should
CEA (Technical Standards
minimize nuisance tripping and should be
for Connectivity of the
lie in operating range 80% to 110% of the
Voltage
Distributed Generation
nominal connected voltage.
Beyond a
Resources) Regulations
clearing time of 2 second, the photovoltaic
2013
system must isolate itself from the grid.
CEA (Technical Standards
Operation of Photovoltaic system should
for Connectivity of the
not cause voltage flicker in excess of the
Flicker
Distributed Generation
limits stated in IEC 61000 standards or
Resources) Regulations
other equivalent Indian standards, if any.
2013
(indicated In Section C)
When the Distribution system frequency
CEA (Technical Standards
deviates outside the specified conditions
for Connectivity of the
(50.5 Hz on upper side and 47.5 Hz on
Frequency
Distributed Generation
Lower side), There should be Over and
Resources) Regulations
under frequency trip Functions with a
2013
clearing time of 0.2 seconds.
CEA (Technical Standards for Photovoltaic system should not inject DC
DC injection
Connectivity of the
current more than 0.5% of full rated output.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
12
13
14
15
16
17
18
19
20
21
Distributed Generation
Resources) Regulations 2013
IEC 61727/ CEA (Technical
Standards for Connectivity
of the Distributed Generation
Resources) Regulations
2013
CEA (Technical Standards for
Connectivity of the
Distributed Generation
Resources) Regulations 2013
CEA (Technical Standards for
Connectivity of the
Distributed Generation
Resources) Regulations 2013
CEA (Technical Standards for
Connectivity of the
Distributed Generation
Resources) Regulations 2013
While the output of the inverter is greater
than 50%,it should operate in the range of
Power Factor
0.9 lag and lead (IEC)./ The inverter should
dynamically operate in the range of 0.95
lag- to lead(CEA)
The photovoltaic system in the event of
Islanding and
fault, voltage or frequency variation must
Disconnection
island/disconnect itself as per IEC
standard in stipulated period.
The inverter should have the facility to
Overload and
automatically switch off in case of
Overheat
overload or overheating and should restart
when normal conditions are restored
Paralleling device of photovoltaic system
Paralleling
shall be capable of withstanding 220% Of
Device
the normal voltage at the interconnection
point.
The total capacity of Solar Power
connected to the distribution Transformer
Capacity of
should be below 40% of Utility transformer
MERC regulation 2015
Plant
capacity. Moreover, individual Solar Plant
capacity should not exceed its customers
approved contract demand
Solar Capacity below 8KW can be injected
at single phase. Moreover above 8kW and
Connection
MERC Regulation 2015
below 150kW it should be at three Phase
Voltage Level clause 5.2
415 Volt. However above 150kW and
below 1MW it should be at 415 V, while
net meter will be installed at 11kV.
The Reconnection of the Distributed
CEA (Technical Standards for
Generation to Grid
in the event of
Connectivity of the
Reclosing
disconnection prior, should happen only if
Distributed Generation
frequency and voltage are stable for atResources) Regulations 2013
least 1 minute.
Capable of being Locked in open position,
Manual Isolating
May not be rated for Load Break nor may
CEA (Technical Standards for
Switch between
have feature of over current protection. It
Connectivity of the
grid and
should
be
reached
quickly
and
Distributed Generation
Distributed
conveniently. Should be located at height
Resources) Regulations 2013
generation
of at least 2.44 meter above the ground
level.
CEA (Technical Standards for
Inspection,
test,
Calibration
and
Connectivity of the
Maintenance prior to connection shall be
Test Certificate Distributed Generation
done by applicant in consultation with the
Resources) Regulations 2013
appropriate licensee is required.
(clause 10)
CEA (Technical Standards for The applicant shall prepare Single Line
Schematic
Connectivity of the
Schematic Diagram in respect of its
Diagrams
Distributed Generation
system facility and make the same
Resources) Regulations 2013 available to the appropriate licensee
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
(clause 9)
22
Power Quality
Measurement
23
Protection
24
Solar meter
Location
25
Statutory
Approval
26
Certification of
Equipments
27
Voltage
Standards
DC current injection, Flicker and harmonic
shall be done with calibrated meters
before commissioning of the project and
once a year in presence of parties
concerned and indicative date shall be
communicated.
Circuit Breakers or other interrupting
equipment shall be suitable for their
indented application with the capability of
CEA (Technical Standards for
interrupting the maximum available fault
Connectivity of the
current. The DG (distributed generation)
Distributed Generation
and associated equipment shall be
Resources) Regulations 2013
designed so that the failure of any single
(clause 7.a,b)
device or component shall not potentially
compromise the safety and reliability of the
system.
The Net Meter and the Solar Generation
Meter shall be installed at such locations in
the premises of the Eligible Consumer as
would enable easy access to the
MERC Regulation 2015
Distribution Licensee for meter reading.
clause 7.8, Annexure 3.2.3
Annexure-3 The Licensee shall specify the
and 3.8.3
interface/inter-connection
point
and
metering point. The uni-directional and bidirectional or pair of meters shall be fixed
in separate meter boxes in the same
proximity.
The Eligible Consumer shall obtain any
statutory approvals and clearances that
may be required, such as from the
MERC Regulation 2015
Electrical Inspector or the municipal or
clause Annexure -3 .4
other authorities, before connecting the
Roof-top Solar PV System to the
distribution Network.
The equipment connected to the
Licensee’s Distribution System shall be
compliant with relevant International
(IEEE/IEC) or Indian Standards (BIS), as
MERC Regulation 2015
the case may be, and the installation of
clause Annexure-3.1
electrical equipment shall comply with the
requirements specified by the Central
Electricity Authority regarding safety and
electricity supply.
CEA (Technical Standards for
Connectivity of the
Distributed Generation
Resources) Regulations 2013
(clause 8.2)
Maharashtra Electricity
Regulation Committee
“Standards of Performance of
Distribution
Licensees”.
The Grid voltage maximum limit is 250 Volt
(i.e. 433 Volt) and ± 6% variation in
voltage.
Table 6: Grid Connectivity technical requirement
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
F. Equipment Features
I.
Solar PV modules and array
1. Crystalline PV modules type.
2. The mechanical structure to withstand gusts of wind / cyclonic wind up to 120km/hr.
3. The offered modules conform to the latest edition of any of the following IEC/ equivalent BIS
Standards for PV module design qualification and type approval:
-
Crystalline Silicon Terrestrial PV Modules : IEC 61215/IS14286
4. PV modules also qualify Salt Mist Corrosion Testing as per IEC61701/IS61701.
5. PV modules used in solar power plants warranted for output wattage, which should not be
less than 90% at the end of 10 years and 80% at the end of 25 years.
II.
Module mounting structure
The PV modules will be mounted on fixed metallic structures of adequate strength and
appropriate design, which can withstand load of modules and high wind velocities up to 120 km
per hour. The support structure used in the power plants will be hot dip Galvanized Iron (G.I).
Note: Point F.I and F.II are guidelines for Applicant, it is not RInfra requirement
III.
Power Conditioning Unit/Inverter
1. The Inverter shall have internal protection arrangement against any sustained fault in the
feeder line and against lightning in the feeder line
2. The inverter shall have the required protection arrangements against earth leakage faults
3. DC lines shall have suitably rated isolators to allow safe start up and shut down of the system
4. Circuit breakers used in the DC lines must be rated suitably
5. The inverter shall preferably have provision for galvanic isolation.
6. Each solid state electronic device shall have to be protected to ensure long life of the inverter
as well as smooth functioning of the inverter
7. The inverter shall include appropriate self protective and self diagnostic feature to protect itself
and the PV array from damage in the event of inverter component failure or from parameters
beyond the inverter’s safe operating range due to internal or external causes.
8. Maximum Power tracking facility should be present..
9. Protection against
I.
Over current
II.
Sync loss
III.
Over temp.
IV.
DC bus over voltage.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
V.
Cooling Fan failure(If provided)
VI.
Grid Under/Over voltage and frequency
10. Dynamic Reactive Power Support to be present in inverter.
11. Integrated protection in the DC and three phase system.
12. Ground Fault and Arc protection should be there for DC (PV array). Moreover, insulation
monitoring of PV array should be there.
13. AC and DC side disconnect switch / MCCB /ACB should be there for protection/isolation.
14. Power regulation in the event of thermal failure.
15. The Inverter should have functionally to limit the fault current contribution from the Distributed
generation to its full load limit. The protection equipments should be designed to protect
against system abnormality.
IV.
ACDB (LT Panel)
1. All outdoor devices/equipment to be IP65 as minimum
V.
DC & AC Switches
1. DC SIDE
a. FUSE /MCB of suitable rating should be provided for array input
b. The Input of the Inverter should have DC isolation switch.
2. AC SIDE
a. MCB/MCCB /ACB of suitable rating shall be provided for connection and
disconnection of Inverter & load.
b. Isolating switches (No load Break) should be provided at incoming of the meter cabin.
c. Isolating switches should be provided at the output of the inverter.
d. The Phase and Earth fault protection embedded switches should be provided at
output of the inverter and also in the meter cabins corresponding to solar circuit.
VI.
Cables and installation accessories

The size of the cables between array interconnections, array to junction boxes, junction
box to PCU, PCU to AC Distribution Box etc shall be so selected to keep the voltage
drop and losses to the minimum. Permissible Wire Drop on DC side shall be <= 2%

All cabling on the roof to be provided with suitable mechanical protection (i.e. cable trays
with top cover or metal conduits). PVC conduits or pipes are not be used.

To minimize the impact of the voltage rise variables such as inverter location, inverter
output-circuit length and conductor size are to be selected accordingly.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
VII.
Earthing and lightning protection
Earthing:

The array structure of the PV yard shall be grounded properly using adequate number of
earthing kits.

All metal casing or shielding of the power plants shall be thoroughly grounded to ensure
safety of the solar power plants.
Lightning:

The PV plants shall be provided with lightning & over voltage protection.

Lightning protection to be as per Indian or relevant IEC standard.

Surge Protection Device Type 1 and 2 to be provided for lightning and surge protection
respectively.
G. Preliminary Site Visit Check List
As given in Annexure – 4
H. Pre-Commissioning Check List
As given in Annexure - 5
I.
I.
Safety
The equipment connected to the Licensee’s Distribution System shall be compliant with relevant
International (IEEE/IEC) or Indian Standards (BIS), as the case may be, and the installation of
electrical equipment shall comply with the requirements specified by the Central Electricity Authority
regarding safety and electricity supply.
II.
The design, installation, maintenance and operation of the Roof-top Solar PV System shall be
undertaken in a manner conducive to the safety of the Roof-top Solar PV System as well as the
Licensee’s Network.
III.
If, at any time, the Licensee determines that the Eligible Consumer’s Roof-top Solar PV System is
causing or may cause damage to and/or results in the Licensee’s other consumers or its assets, the
Eligible Consumer shall disconnect the Roof-top Solar PV System from the distribution Network
upon direction from the Licensee, and shall undertake corrective measures at his own expense
prior to re-connection.
IV.
The Licensee shall not be responsible for any accident resulting in injury to human beings or
animals or damage to property that may occur due to back- feeding from the Roof-top Solar PV
System when the grid supply is off. The Licensee may disconnect the installation at any time in the
event of such exigencies to prevent such accident.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
V.
The Isolating switches should be provided at output and the input of the Inverter. Moreover,
protection switches as indicated in Annexure should have Phase and earth Fault Protection.
VI.
The Meter cabin and corresponding switchgear should be easily accessible.
VII.
The Body Earthing of each and every equipment should be followed as per standards. (Atleast at
two separate points for each equipment viz. solar panel, inverter etc should be done from two
separate connected earth pits).
VIII.
Standard shutdown procedure to be located close to the inverter. Each circuit switches should be
indicated by the red colored signage (Aluminum plate).
Fig 1: Standard Shutdown Procedure Near Inverter (Laminated Paper fixed to Wall- Font size 16 Arial)
Note:
All Signage should be engraved (red color letter and height 7mm) on Aluminum plate with
rivet for fitting at relevant locations. Points I-IV Refer MERC Regulation -2015 Annexure-3 clause 3.
1. Date Of Commissioning
2. Contact Number responsible for O&M of Plant
3. Peak Plant Capacity (KW)
4. No of Inverters with each rating
5. Inverter AC voltage and current
6. Inverter DC input Voltage and current
7. Short Circuit current fed by Inverter during fault
8. No of PV Panels
9. No of Strings
10. No of PV Panel in each Strings
11. Voc of a PV Panel
12. Isc of a PV panel
Fig 2: Specification on the Meter Cabin (Laminated Paper and Fixed in meter cabin-Font size 16 Arial)
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
CAUTION
SOLAR ELECTRIC
SYSTEM
LOAD SWITCH
SOLAR SWITCH
NET SWITCH
RINFRA SWITCH
SOLAR METER
NET METER
Fig 3: Signage to be fitted near the components in the meter cabin
INVERTER
AC DISCONNECT SWITCH
INVERTER
DC DISCONNECT SWITCH
Fig 4: Signage near Inverter
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
Annexure - 1
SLD are categorized accordingly to Generating capacity of PV(Photo Voltaic) plant and voltage level
(Refer: MERC regulation clause 5.2).
Case1:: Typical SLD of grid Connected Roof Top PV with capacity below 8kW – single-phase
B
DC
A
Solar
meter
Rinfra MCB/Fuse
Grid
Net
Meter
Solar
Inverter
Surge protection
Load
Load
Fig A.1: Typical SLD of grid Connected Roof Top PV with capacity below 8kW
1. The solar circuit switch “B” should have provision for Phase and earth fault protection.
2. On DC input side and AC output side of the Inverter, should have isolation switch.
3. Rinfra MCB will be of same rating as per existing policy guidelines.
4. The Inverter AC side (as indicated in SLD) and DC side (after DC connector box but input of
inverter) should have isolation switch.
5. If applicant needs to operate in islanded mode during grid failure. The provision should be
made by the customer to automatically trip switch A (shown in SLD) to avoid flow of power in to
the grid/utility. Otherwise, customer should make provision for manual isolation switch A.
6. The separate meter boxes should be there to accommodate solar meter and bidirectional
meter. Moreover, both meters should be in close proximity. The Net Meter and the Solar
Generation Meter shall be installed at such locations in the premises of the Eligible Consumer
as would enable easy access to the Distribution Licensee for meter reading.
7. Rating of all switches viz inverter, consumer and switch A will be selected based upon rating/
capacity of load and generation. It shall be procured by customers only.
8. In case of multiple injections from single-phase DG connected to the same upstream DT,
RInfra shall ensure that they are on alternate phases to prevent undue Voltage imbalance.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
Annexure – 2
Case-2 :: Typical SLD for grid Connected Roof Top PV with capacity above 8kW and below
150kW – for Three-phase
Solar Panel
Inverter Switch
Solar Inverter
ACDB (AC
Distribution Board)
Isolating
Transformer
Star /Delta
Switch
B
A
Solar
Meter
DC fuse
Inverter
Rinfra Switch
Net
Meter
Consumer ACDB
Surge protection
Load Switch
Load
Fig A.2: Typical SLD for grid Connected Roof Top PV with capacity above 8kW and below 150kW
1. Rinfra Switch should be as per our existing policy:
2. The Inverter AC side (as indicated in SLD) and DC side (after DC connector box but input of
inverter) should have isolation switch.
3. The isolating Transformer (Galvanic Isolation) is advisable in case of load above 8KW solar
generation.
9. If applicant needs to operate in islanded mode during grid failure. The provision should be
made by the customer to automatically trip switch A (shown in SLD) to avoid flow of power in to
the grid/utility. Otherwise, customer should make provision for manual isolation switch A.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
4. The size of the ACDB should be able to accommodate the switch A, and B (along with manual
isolation switch, as per MERC Regulation). The ACDB should be provided by the applicant.
5. The Net Meter and the Solar Generation Meter shall be installed at such locations in the
premises of the Eligible Consumer as would enable easy access to the Distribution Licensee
for meter reading. Moreover they should be in separate boxes and in close proximity.
6. If Isolation transformer is not there, then corresponding solar side transformer switch may not
be present.
7. Rating of all switches viz inverter, consumer and switch A will be selected based upon rating
capacity of load and generation. Moreover, the inverter switch and switch A, B should have
earth fault and phase protection i.e 50-50N and 51-51N relay.
Note:
1. 50-50N Instantaneous Phase and earth fault relay
2. 51-51N Over current Phase and Earth fault relay.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
Annexure – 3
Case 3:: Typical SLD grid Connected Roof Top PV with capacity above 150kW – Three-phase
Inverter
DC fuse
Solar Panel
Two winding
Isolating 415/415
Volt
Delta/Star
ACB
50-50N and
51-51N
ACB
50-50N and 51-51N
Surge protection
Solar meter
ACDB
ACB
50-50N
and 5151N
ACB
50-50N and
51-51N
0.415/11kV
Star/Delta
Load
Net meter
A
Consumer 11kV
Breaker
50-50N and 51-51N
RInfra RMU
Fig A.3:; Typical SLD grid Connected Roof Top PV with capacity above 150kW
1. Rinfra 11kV Switchgear should be as per our existing policy:
2. The Inverter AC (as indicated in SLD) and DC side (after DC connector box but input of
inverter) should have isolation switch.
3. Inverter Main SFU/MCCB (switch B) should be in accordance with total capacity of Solar
generation (i.e. it may be 110% of the full load rating of the inverter). The ACB should have
with 50-50N and 51-51N protection relay.
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
4. If applicant needs to operate in islanded mode during grid failure. The provision should be
made by the customer to automatically trip switch A (shown in SLD) to avoid flow of power in to
the grid/utility.
5. The Net Meter and the Solar Generation Meter shall be installed at such locations in the
premises of the Eligible Consumer as would enable easy access to the Distribution Licensee
for meter reading. Moreover they should be in separate boxes and in close proximity.
Annexure – 4
Preliminary Site Survey Check List (after Application)
Sr.No
Description
1
Capacity of the proposed PV Plant
Contract Demand (Sanctioned Load) of
2
Consumer
Existing Network SLD details up to the
Consumers Point of Supply and Last mile
connectivity. The SLD should Indicate existing
3
protection equipment (Fuse Rating, Voltage,
MCB/MCCB, ACB rating), cable size,
transformer size and loading of equipments
uptil Point of supply i.e. Upstream network
Existing protection (MCB/Fuse/Breaker) details
4
and SLD after Meter – of Consumer
AC Voltage Level at which connectivity is
5
sought
Rated output AC Voltage of the proposed Solar
6
Plant (230,415 Volt).
Available cumulative capacity of relevant DT
7
and substation Name
Space availability/feasibility to commission new
8
Meter cabin /Panel accommodating Net meter,
Solar Meter and Isolating switches.
Consumer advised to ensure readiness of the
meter cabin of adequate size to accommodate
equipment as per relevant SLD along with work
9
completion report (Plant Setup Intimation).
Moreover, intimation to furnish the documents
prior to commissioning test.
Y/N/Value
Remarks
Note: Preliminary Site Survey Activity to be done by Divisional Load remark and Business team
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CES Department
Annexure - 5
Commissioning Check List
Sr.
No
1
Description
Y/N/Value
Remarks
New Meter Cabin of requisite dimensions ready
Automation-compliant motorized Islanding Switch
(A – as per concept SLD) is installed.
2 (In case Anti-islanding is not there or for Island
operation with Battery or Diesel Generator is
planned by applicant).
Protection switch ‘B’ (as per SLD) installed is
3
having Phase & Earth Fault protection
The switches are there as per SLD shown in
4
Annexure 1,2 and 3
5 Solar /Net Meter is installed
Danger Board/Signage as Shown in Section I are
6
incorporated at suitable locations.
7 Voltage magnitude at point of connection with grid. 230V/420 V
8 Full Load output Power of Plant in KW
AC and DC side manual isolating switches located
9
near inverter.
Surge Protection (Type-II) device is installed on
10
AC/DC side of Inverter
11 Voltage magnitude at the output of inverter
230V/420V
The DC/AC Ground Fault monitoring Feature in
12
Inverter
Is Isolation Transformer (if applicable) installed -- to
13 avoid DC current injection, harmonic injection and
protect inverter from grid disturbances.
Under (80%) /Over (110%) Voltage and Under
(47.5)/Over (50.5) frequency protection for
14 Islanding is inbuilt in Inverter with minimum
clearing time 2 sec(for voltage) and 0.2 sec (for
frequency) respectively (as per section C)
Power Quality Norms viz. harmonic limits, flicker
and DC current (refer Section C). The customer
15
should
provide
test
report
from
the
government/NABL accredited Labs.
a
TDD Harmonic level in (5%)
b
DC Injection (0.5 % of FLC)
c
Flicker – Interval / Value (Plt/Pst)
Inverter should be configured to provide Dynamic
Reactive support. The settings should be 0.95
16 Power factor (capacitive and inductive) (for 8KW to
150KW) and 0.90 power factor for (150 KW and
above) according to grid voltage variation.
17 The reconnection time should be 1 minute
The document indicating details of fault
18 contribution by inverter ( time, voltage and current
magnitude in tabular form)
19 Anti-islanding feature available in inverter as tested
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CES Department
20
21
22
21
22
23
24
IEC62116 or IEE1547
Is Earthing of Solar PV followed as per IS 3043
Is Lightning Protection provided
If PV is Single Phase, whether load balancing is Y/N
required to be done by RInfra.
Has Customer provided single document to
indicate single line drawing with protection
details/ratings, Load Connectivity/Details, earthing
details, Lightning protection, Inverter(protection
features and make) and Solar PV panel details
(ratings and connectivity).
Undertaking by applicant for internal Power Quality
check every year for the PV output above 150kW
and every 2 years for less than 150 kW to 8kW.
The Solar Installation approved by PWD Electrical
Inspector.
Responsibility matrix /ownership of Equipment
Maintenance Undertaking furnished by the
applicant.
Note:
1. Points 11 to 19 are the inverter features likely to be present /configured. The documents indicating its
presence should be submitted to Business team and verified by Load remark team. Moreover, its need
should be communicated /explained to consumer during application itself. Furthermore, the compliance of
documents indicating the details of inverter from point 11 to 19 should be checked /confirmed prior to
commissioning visit.
2. Point’s 21, 22, 23 and 24 document compliance need to be checked/confirmed by Business team prior to
commissioning visit. After Submission of Test report (harmonics, flicker, DC injection and reactive
Support) by the Applicant to Businees team, RInfra Divisional Load remark team may check its validity by
performing on site testing.
3. Commissioning Check Activity to be done by Divisional Load remark and Business team.
4. Applicant’s Power factor degradation may occur due to lowering Active power import from grid. (it needs
to communicated to consumer)
Annexure - 6
Dimensions of Equipments
Sr.No
1
2
3
4
5
6
7
Description of Equipment
Single phase meter
Three Phase meter (in built CT)
Single phase MCB
Single Phase MCB with casing
Neutral Link-63AMp
Neutral Link-100AMp
Single Phase with Neutral MCB
Technical Guidelines for Grid Tied Distributed Generation (Solar)
Height
140
200
100
130
100
140
100
Width
140
200
20
50
90
110
40
Depth
100
100
80
80
40
40
80
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CES Department
8
Three Phase MCB
100
60
80
9
Three Phase Neutral MCB
100
80
80
10
100 Amp Fuse unit
250
330
155
11
200 Amp Fuse unit
350
375
180
12
400 Amp Fuse unit
440
425
180
13
On load sitch Disconnector-400A
1000
400
275
14
630Amp SDF
1300
500
370
15
800Amp SDF
1300
500
370
16
63Amp SDF
400
250
200
17
100Amp SDF
400
350
250
18
200Amp SDF
750
350
260
19
400Amp SDF
850
400
275
20
800 Amp MCCB
400
300
150
21
1250 Amp MCCB
400
300
150
All dimensions in mm
Note
1
Wire should be clipped at 50mm interval at regular interval
2
The Height of LT Incoming switchgear shall be 0.9 meters above the ground
level.
3
Board wiring shall be carried out only on Fire retardant plywood of 19 mm
thickness provided by the applicant.
4
Current capacity for 10sqmm wire is 51A and for 4sqmm is 29A as per IS:3961
5
Safety operating clearance from the wall on which meters are installed shall be
1.5m
6
LT Switchgear earthing to main GI strip by means of 25X3 GI flat at diagonally
opposite ear thing bolts to be provided on FU / SDF
7
Single phase ELCB is twice the width of Single Phase MCB
8
Three phase ELCB size is same for Three phase and Neutral MCB
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CES Department
Annexure – 7
Sample Documents---- NEED NOT BE OF SAME FORMAT
Documents 1, 2 and 3 should be Type test report or from NABL accredited lab report
1. Harmonics Report
2. Flicker
3. DC Current Injection
4. Fault current contribution
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CES Department
5. Voltage and Frequency protection
The Routine test report available from inverter manufacturer indicating protection features present in
inverter. However, it should be configured as per CEA Guidelines
6. Routine Test report indicating Reconnection time settings, it has to be configured as per CEA
Guidelines.
7.
Reactive Support routine test report, it should be reconfigured as per CEA guidelines.
At 240 volt (Nominal Voltage) to 245 Volt it should operate at unity power factor. However, grid voltage
reduces, inverter should operate in leading power factor with linearly increasing trend up to 230 Volt, and
then it becomes fixed with 0.95 lead (i.e. 30% capacitive). Similarly, for voltage range from 245 to 255
Volt the Inverter should absorb reactive power gradually with maximum power factor 0.95 (i.e. Inductive
30%).
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CES Department
8. DC side ground fault monitoring feature in the inverter. It can confirm from datasheet of the inverter.
Similar for AC side ground fault monitoring feature.
9. Sample Data Sheet of Inverter
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CES Department
10. Detail drawing of Plant Setup
Technical Guidelines for Grid Tied Distributed Generation (Solar)
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CES Department
1.
2.
3.
4.
5.
6.
Voc =36 Volt
Isc =8Amp
Vdc =600 Volt
Vac=415 volt
I= 20 Amp
Inverter output=20KW
Manual Switch
100 Amp MCCB +
100 milliamp
ELCB
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