This document provides an overview of grid interconnection and commissioning test procedures for solar PV rooftop systems in India. It discusses the key factors in determining interconnection and metering based on state regulations and distribution utilities. It also outlines the applicable standards and regulations, technical specifications including single line diagrams, and test requirements for grid connectivity and commissioning. Specifically, it describes the unintentional islanding functionality test that verifies the inverter will cease exporting power within 2 seconds of loss of grid connection and not resume for over 60 seconds after reconnection.

1. Partnership To Advance Clean Energy-Deployment (PACE-D)
Technical Assistance Program
Presented by
USAID PACE-D TA Program
Apr-18
Solar PV Rooftop Training Program For Entrepreneurs
Session:
Grid Interconnection & Commissioning Test Procedures

2. Contents
Interconnection and metering – What are the deciding
factors?
Single Line Diagrams for different types of interconnections
Applicable standards and regulations for grid connectivity
Interconnection technical specification and requirements

3. Contents
Interconnection test specification and requirements
Commissioning tests
Unintentional islanding functionality test

4. Interconnection & Metering – Deciding Factors
1
 State regulation by SERC
2
 Distribution utility whose grid would be utilized
3
 Capacity of SPVRT plant
4
5
 Program framework – gross or net metering
 Voltage levels where energy to be injected

5. Interconnection & Metering – Examples of 3 States
Supply
Voltage
Madhya Pradesh Rajasthan Maharashtra
230V, 1 phase Up to 3kW Up to 5kW Up to 8 kW / 40 A
415V, 3 phase >3kW to 112 kW >5kW to 18.65 kW >8 kW to 150 kW
>8 kW to 80 kW
11kV, 3 phase > 112kW to 300kW >18.65kW to 50kW >150 kW to 1000
kVA
>80 kW to 1000 kVA
33kV, 3 phase >300kW to
10,000kW
>50 kW

6. Single Line Diagram – Gross Metering: Grid Tied LT

7. Single Line Diagram – Gross Metering: Grid Tied HT

8. Single Line Diagram – Net Metering: Grid Tied LT

9. Single Line Diagram – Net Metering: Grid Tied HT

10. Single Line Diagram – Gross Metering Using 2
Meters
This is typically a gross metered connection and Meter 2 is export meter

11. Single Line Diagram – Net Metering Using 1 Meter
This is typically a net metered connection and Meter 1 is net meter (bi-directional)

12. Single Line Diagram – Net Metering Using 2 Meters
This is typically a net metered connection as mandated in many state regulations and
Meter 1 is net meter (bi-directional) whereas Meter 2 is Solar (Generation) Meter

13. Single Line Diagram – Net Metering for Multiple
Buildings
This is typically a colony of buildings with number of installations with net metered
connection and all meters are net meters (bi-directional)

14. Single Line Diagram – Gross Metering for Multiple
Buildings
This is typically a gross metered connection and Meter 1 is consumer meter and Meter
2 is Solar (Generation) meter

15.  Central Electricity Authority (Technical Standards for Connectivity of the
Distributed Generation Resources) Regulations 2013
 IEEE 1547 – Standard for Interconnecting Distributed Resources with Electric
Power System, 2003
 Central Electricity Authority (Measures Relating to Safety and Electricity
Supply) Regulations, 2010
 Central Electricity Authority (Technical Standards for Connectivity to the grid)
Regulations 2007
 IEEE 519: Recommended Practice and Requirements for Harmonic Control in
Electric Power Systems, 2014
Applicable Standards & Regulations for Grid
Connectivity

16. Interconnection Technical Specifications &
Requirements
General Requirements (IEEE 1547 / CEA Regulation 2013)
Voltage Regulations
The distributed resources shall
not actively regulate the
voltage at the point of
interconnection
Synchronization
The distributed resource
synchronized with electric
system shall not cause a
voltage fluctuation at the
point of interconnection
greater than ±5%
Monitoring Provision
Each distributed resource of
250 kVA or more at a single
point of interconnection shall
have provisions for monitoring
its connections status, real
power output, reactive power
output and voltages at the
point of interconnection

17. Interconnection Technical Specifications &
Requirements
General Requirements (IEEE 1547 / CEA Regulation 2013)
Isolation Device
There should be a manually operating isolating switch between distributed generation resource
and electric system, which meets the following requirements:
 Allow visible verification that separation has been established
 Indicators to show clearly closed and open position
 Be readily accessible and be capable of being locked in open position
 May not be rated for load-break
 Be located at height of 2.44 m above ground level

18. Interconnection Technical Specifications &
Requirements
General Requirements (IEEE 1547 / CEA Regulation 2013)
Interconnect Integrity
 Interconnection system shall have the capability to withstand electromagnetic interference
 Paralleling device shall withstand 220% of interconnection system rated voltage
 Interconnection system shall have the capability to withstand voltage and current surge

19. Interconnection Technical Specifications &
Requirements
Response to Abnormal Conditions (IEEE 1547 / CEA Regulation 2013)
Voltage
Inverter must have over and
under voltage trip functions if
voltage reaches above 110%
or below 80% respectively with
clearing time up to two
seconds
Frequency
Inverter must have over and
under frequency trip functions
if frequency reaches 50.5 Hz
and below 47.5 Hz with a
clearing time of 0.2 seconds
Islanding
Inverter must have function to
prevent formation of
unintended island, and cease
to energise the electricity
system within 2 seconds

20. Interconnection Technical Specifications &
Requirements
Power Quality (IEEE 1547 / CEA Regulation 2013)
Limitation on DC Injection
The rooftop solar and its
interconnection system shall
not inject dc current greater
than 0.5% of the full rated
output current
Limitation of Flicker
The distributed resource shall
not cause objectionable flicker
on the electric system (IEC
61000)
Harmonics
The distributed resource shall
not inject harmonic current
greater than 5% at the electric
system (IEEE 519)

21. Commissioning Tests
 All commissioning tests shall be performed based on written test procedures of
equipment manufacturer / system integrator
 A visual inspection shall be made to ensure that the system earthing is adequate as
per standard / regulation
 A visual inspection shall be made to confirm the presence of the isolation device as
required by standard / regulation
 The following initial commissioning tests shall be performed on the installed solar PV
rooftop system and grid connected inverter prior to the initial parallel connection to
the grid:
 Operability test on the isolation device
 Unintentional islanding functionality

22. Unintentional Islanding Functionality Test
If there is more than
one inverter, tests
should be carried out
for each inverter
SPVR system should
produce more than
20% of the rated
output of the SPVRT
Array or the inverter
– whichever is less
This test must be
conducted during
noon time on a
sunny day

23. Unintentional Islanding Functionality Test – Test 1
Test 1: Inverter must cease supplying power within 0.2 seconds of loss of
mains
Step 1:
Keep DC supply from the SPVRT array connected to the inverter
Step 2:
Place the voltage probe in the inverter side of the AC main switch
Step 3:
Turn OFF the main switch, through which inverter is connected to grid
Step 4:
Measure time taken for inverter to cease attempting to export power
with a timing device and record

24. Unintentional Islanding Functionality Test – Test 2
Test 2: Inverter must not resume supplying power until mains have been
present for more than 60 seconds
Step 1:
Keep DC supply from the SPVRT array connected to the inverter
Step 2:
Place the current probe in the inverter side of the AC main switch
Step 3:
Turn ON the main switch, through which inverter is connected to grid
Step 4:
Measure time taken for inverter to re-energize and start exporting
power with a timing device and record

25. 25
Anurag Mishra
Senior Clean Energy Specialist
USAID/India
Email: amishra@usaid.gov
Disclaimer:
This training material is made possible by the support of the American
People through the United States Agency for International
Development (USAID). The contents of this material are the sole
responsibility of Nexant, Inc. and do not necessarily reflect the views of
USAID or the United States Government. This material was prepared
under Contract Number AID-386-C-12-00001.