Technical Guidelines for Grid Tied Distributed Generation

Central Engineering ServicesSystem Studies and Engineering

Technical Guidelines for Grid Tied

Distributed Generation (Solar)

CES-SYS-2015-6

Revision R1Prepared by Checked by Reviewed by Approved by

23/05/2016D.G.M A.V.P V.P

Head CES Sr.Exec.V.P

Ashutosh Pailwan

Indranil Chatterjee Dhruv Palekar Anup Mondal

CCEESS DDeeppaarrttmmeenntt

Technical Guidelines for Grid Tied Distributed Generation (Solar) . i

Record of Revision Sr.No Revision

No Item/Clause No Nature of Change Approved By

1 R1 D Table Addition DSP/AM 2 R1 E Addition DSP/AM 3 R1 I.VIII Added DSP/AM 4 R1 Anexxure 1.1 to 1.8 Added and Edit DSP/AM 5 R1 Anexxure 2.1 to 2.7 Added and Edit DSP/AM 6 R1 Annexure 5.24 to 5.8 &Note Added and Edit DSP/AM 7 R1 Annexure6 Addition DSP/AM 8 R1 Annexure-3.1 to 3.5 Added and Edit DSP/AM 9 R1 Annexure-4 (10th Count) Deletion DSP/AM

10 R1 Annexure-7 Addition DSP/AM


Technical Guidelines for Grid Tied Distributed Generation (Solar) . ii

Content: Sr. No. Description Page No

A Introduction 1

B Salient Stipulations in MERC Reg. 2015 1

C Codes and Standards 2

D IEEE 519 Harmonic Standards and IEC 61000-3-3 Flicker Standards 3

E Technical requirement of the Grid Connected Roof Top Solar 3

F Equipment Features 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) . iii

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 519-1992, 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 3-6


Technical Guidelines for Grid Tied Distributed Generation (Solar) . iv

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 Typical SLD of grid Connected Roof Top PV with capacity below 8kW 12

A.2 Typical SLD for grid Connected Roof Top PV with capacity above 8kW and below 150kW 13

A.3 Typical SLD grid Connected Roof Top PV with capacity above 150kW 15


Technical Guidelines for Grid Tied Distributed Generation (Solar) Page 1 of 25

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, AEML 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 AEML shall not exceed 40 % of its Capacity (Cl.4.1)

3. AEML 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)

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 AEML Grid

in absence of Grid supply. (Cl.6.2)

8. Consumer shall provide adequate protection for Islanding the RT-SPV from AEML Network in

the event of grid supply failure (Cl.6.4)

9. AEML 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 AEML) and also Solar

Generation Meter (procured & installed by Consumer or AEML, 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 1-2

Requirements for construction & requirements for testing, for safety qualification

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- 13703

Low voltage fuses

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 IS 3043 Earthing Standards IEC 62305 Lightning Protection IEC 62446 Operation , Maintenance and Documentation IS 732 Wiring Rules CEA -2007 Technical Standards for connection to grid 2007 ( amendment 2013) CEA-2013 Technical standard for Connectivity of the Distributed generation resources

regulation 2013 MERC -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) Individual Harmonic Voltage

Distortion (%) Total Voltage Distortion, THDVn (%)

Vn ≤ 69 2 5

69 ≤ Vn ≤161 1.5

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)

Short Circuit ratio at PCC Max individual frequency voltage harmonic (%) Related Assumption

10 2.5-3.0 Dedicated system

20 2-2.5

1-2 Large customer

50 1-1.5 A few relatively large customer 100 0.5-1.0 5-20 medium size customer 1000 0.05-0.10 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 4 2 1.5 0.6 0.3 5

20-50 7 3.5 2.5 1 0.5 8



50-100 10 4.5 4 1.5 0.7 12 100-1000 12 5.5 5 2 1 15

>1000 15 7 6 2.5 1.4 20 Table 4: Harmonic Current Distortion limits (Ih) in percent of IL

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)

Value Observation Interval Limiting Value Pst (Short term flicker "perceptibility" value) 10 min 1.0

Plt (Long term flicker "perceptibility" value) 2 h 0.65

Table 5: Flicker standard IEC 61000-3-3

E. Technical requirement of the Grid Connected Roof Top Solar

Sr.No Parameter Reference Requirement

1 Overall

conditions of service

State Distribution/Supply Code Reference to State Distribution Code

2 Overall Grid Standards CEA Regulation 2010 Reference to regulations

3 Equipment BIS / IEC / IEEE Reference to standards

4 Meters Central Electricity authority (Installation & operation of meters) Regulation 2006

Reference to regulations and additional conditions issued by the Commission.

5 Safety and supply

Central Electricity authority (measure for safety and electricity supply) Regulation 2010

Reference to regulations

6

Harmonic Requirements

Harmonic Current

IEEE 519, CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations 2013

Harmonic current Injections from a generating station shall not exceed the limits specified in IEEE 519 (indicated in Section D)

7 Synchronization

CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations 2013

Photovoltaic system must be equipped with a grid frequency synchronization device. Every time the generating station is synchronized to the electricity System, It shall not cause voltage fluctuation greater than +/- 5% at point of connection.

8 Voltage


The voltage-operating window should minimize nuisance tripping and should be lie in operating range 80% to 110% of the nominal connected voltage. Beyond a clearing time of 2 second, the photovoltaic

http://www.cea.nic.in/reports/regulation/distribution_notified.pdf�
















system must isolate itself from the grid.

9 Flicker


Operation of Photovoltaic system should not cause voltage flicker in excess of the limits stated in IEC 61000 standards or other equivalent Indian standards, if any. (indicated In Section C)

10 Frequency


When the Distribution system frequency deviates outside the specified conditions (50.5 Hz on upper side and 47.5 Hz on Lower side), There should be Over and under frequency trip Functions with a clearing time of 0.2 seconds.

11 DC injection


Photovoltaic system should not inject DC current more than 0.5% of full rated output.

12 Power Factor

IEC 61727/ 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 0.9 lag and lead (IEC)./ The inverter should dynamically operate in the range of 0.95 lag- to lead(CEA)

13 Islanding and Disconnection


The photovoltaic system in the event of fault, voltage or frequency variation must island/disconnect itself as per IEC standard in stipulated period.

14 Overload and Overheat


The inverter should have the facility to automatically switch off in case of overload or overheating and should restart when normal conditions are restored

15 Paralleling Device


Paralleling device of photovoltaic system shall be capable of withstanding 220% Of the normal voltage at the interconnection point.

16 Capacity of Plant MERC regulation 2015

The total capacity of Solar Power connected to the distribution Transformer should be below 40% of Utility transformer capacity. Moreover, individual Solar Plant capacity should not exceed its customers approved contract demand

17 Connection Voltage Level

MERC Regulation 2015 clause 5.2

Solar Capacity below 8KW can be injected at single phase. Moreover above 8kW and below 150kW it should be at three Phase 415 Volt. However above 150kW and below 1MW it should be at 415 V, while net meter will be installed at 11kV.

18 Reclosing CEA (Technical Standards for Connectivity of the Distributed Generation

The Reconnection of the Distributed Generation to Grid in the event of disconnection prior, should happen only if



































Resources) Regulations 2013 frequency and voltage are stable for at-least 1 minute.

19

Manual Isolating Switch between

grid and Distributed generation


Capable of being Locked in open position, May not be rated for Load Break nor may have feature of over current protection. It should be reached quickly and conveniently. Should be located at height of at least 2.44 meter above the ground level.

20 Test Certificate

CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations 2013 (clause 10)

Inspection, test, Calibration and Maintenance prior to connection shall be done by applicant in consultation with the appropriate licensee is required.

21 Schematic Diagrams

CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations 2013 (clause 9)

The applicant shall prepare Single Line Schematic Diagram in respect of its system facility and make the same available to the appropriate licensee

22 Power Quality Measurement

CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations 2013 (clause 8.2)

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.

23 Protection

CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations 2013 (clause 7.a,b)

Circuit Breakers or other interrupting equipment shall be suitable for their indented application with the capability of interrupting the maximum available fault current. The DG (distributed generation) and associated equipment shall be designed so that the failure of any single device or component shall not potentially compromise the safety and reliability of the system.

24 Solar meter Location

MERC Regulation 2015 clause 7.8, Annexure 3.2.3 and 3.8.3

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. Annexure-3 The Licensee shall specify the interface/inter-connection point and metering point. The uni-directional and bi-directional or pair of meters shall be fixed in separate meter boxes in the same proximity.

25 Statutory Approval

MERC Regulation 2015 clause Annexure -3 .4

The Eligible Consumer shall obtain any statutory approvals and clearances that may be required, such as from the





























Electrical Inspector or the municipal or other authorities, before connecting the Roof-top Solar PV System to the distribution Network.

26 Certification of Equipments

MERC Regulation 2015 clause Annexure-3.1

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.

27 Voltage Standards

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

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 AEML 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.

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.

VII. Earthing and lightning protection

• The array structure of the PV yard shall be grounded properly using adequate number of

earthing kits.

Earthing:

• All metal casing or shielding of the power plants shall be thoroughly grounded to ensure

safety of the solar power plants.

• The PV plants shall be provided with lightning & over voltage protection.

Lightning:

• 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. Safety

I. 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.

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.

Fig 2: Specification on the Meter Cabin (Laminated Paper and Fixed in meter cabin-Font size 16 Arial)

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

CAUTION SOLAR ELECTRIC

SYSTEM



Fig 3: Signage to be fitted near the components in the meter cabin

Fig 4: Signage near Inverter

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

Grid B DC

Solar

Surge protection Inverter

Load

AEML MCB/Fuse

Net Meter

Load

A Solar meter

NET SWITCH SOLAR SWITCH LOAD SWITCH

SOLAR METER NET METER

INVERTER AC DISCONNECT SWITCH

INVERTER DC DISCONNECT SWITCH

AEML SWITCH



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. AEML 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,

AEML shall ensure that they are on alternate phases to prevent undue Voltage imbalance.

Annexure – 2

Case-2 :: Typical SLD for grid Connected Roof Top PV with capacity above 8kW and below 150kW – for Three-phase

Isolating Transformer Star /Delta

Surge protection

AEML Switch

Net Meter

Consumer ACDB

A B

Solar Meter

Solar Inverter ACDB (AC Distribution Board)

Inverter Switch Solar Panel

DC fuse Inverter



Fig A.2: Typical SLD for grid Connected Roof Top PV with capacity above 8kW and below 150kW

1. AEML 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


3. The isolating Transformer (Galvanic Isolation) is advisable in case of load above 8KW solar

generation.



the grid/utility. Otherwise, customer should make provision for manual isolation switch A.

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

Switch



2. 51-51N Over current Phase and Earth fault relay.

Annexure – 3

Case 3:: Typical SLD grid Connected Roof Top PV with capacity above 150kW – Three-phase

ACB 50-50N and 51-51N

Two winding Isolating 415/415 Volt Delta/Star

Surge protection

ACB 50-50N and 51-51N Solar Panel

DC fuse

Inverter



Fig A.3:; Typical SLD grid Connected Roof Top PV with capacity above 150kW

1. AEML 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


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.



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)

ACDB

ACB 50-50N and 51-51N

AEML RMU

0.415/11kV Star/Delta

A Consumer 11kV Breaker 50-50N and 51-51N

Net meter

ACB 50-50N and 51- 51N

Load

Solar meter



Sr.No Description Y/N/Value Remarks

1 Capacity of the proposed PV Plant

2 Contract Demand (Sanctioned Load) of Consumer

3

Existing Network SLD details up to the Consumers Point of Supply and Last mile connectivity. The SLD should Indicate existing 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

4 Existing protection (MCB/Fuse/Breaker) details and SLD after Meter – of Consumer

5 AC Voltage Level at which connectivity is sought

6 Rated output AC Voltage of the proposed Solar Plant (230,415 Volt).

7 Available cumulative capacity of relevant DT and substation Name

8 Space availability/feasibility to commission new Meter cabin /Panel accommodating Net meter, Solar Meter and Isolating switches.

9

Consumer advised to ensure readiness of the meter cabin of adequate size to accommodate equipment as per relevant SLD along with work completion report (Plant Setup Intimation). Moreover, intimation to furnish the documents prior to commissioning test.

Note: Preliminary Site Survey Activity to be done by Divisional Load remark and Business team

Commissioning Check List Annexure - 5

Sr. No

Description Y/N/Value Remarks

1 New Meter Cabin of requisite dimensions ready

2

Automation-compliant motorized Islanding Switch (A – as per concept SLD) is installed. (In case Anti-islanding is not there or for Island operation with Battery or Diesel Generator is planned by applicant).



3 Protection switch ‘B’ (as per SLD) installed is having Phase & Earth Fault protection

4 The switches are there as per SLD shown in Annexure 1,2 and 3

5 Solar /Net Meter is installed

6 Danger Board/Signage as Shown in Section I are 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

9 AC and DC side manual isolating switches located near inverter.

10 Surge Protection (Type-II) device is installed on AC/DC side of Inverter

11 Voltage magnitude at the output of inverter 230V/420V

12 The DC/AC Ground Fault monitoring Feature in Inverter

13 Is Isolation Transformer (if applicable) installed -- to avoid DC current injection, harmonic injection and protect inverter from grid disturbances.

14

Under (80%) /Over (110%) Voltage and Under (47.5)/Over (50.5) frequency protection for Islanding is inbuilt in Inverter with minimum clearing time 2 sec(for voltage) and 0.2 sec (for frequency) respectively (as per section C)

15

Power Quality Norms viz. harmonic limits, flicker and DC current (refer Section C). The customer 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)

16

Inverter should be configured to provide Dynamic Reactive support. The settings should be 0.95 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

18 The document indicating details of fault contribution by inverter ( time, voltage and current magnitude in tabular form)

19 Anti-islanding feature available in inverter as tested IEC62116 or IEE1547

20 Is Earthing of Solar PV followed as per IS 3043 21 Is Lightning Protection provided

22 If PV is Single Phase, whether load balancing is required to be done by AEML.

Y/N

21 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).

22 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.

23 The Solar Installation approved by PWD Electrical Inspector.

24 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, AEML 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)

Dimensions of Equipments

Annexure - 6

Sr.No Description of Equipment Height Width Depth 1 Single phase meter 140 140 100 2 Three Phase meter (in built CT) 200 200 100 3 Single phase MCB 100 20 80 4 Single Phase MCB with casing 130 50 80 5 Neutral Link-63AMp 100 90 40 6 Neutral Link-100AMp 140 110 40 7 Single Phase with Neutral MCB 100 40 80 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

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



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%).



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



10. Detail drawing of Plant Setup



1. Voc =36 Volt 2. Isc =8Amp 3. Vdc =600 Volt 4. Vac=415 volt 5. I= 20 Amp 6. Inverter output=20KW

100 Amp MCCB + 100 milliamp

Manual Switch