Grid Connected Rooftop PV Systems - Smart Cities India expo · Rooftop PV project development phases • Inception / concept – Identify a potential PV project • Project model

creating sustainable change through education, communication and leadership © 2012 GSES P/L Training • Consulting • Engineering • Publications

GSES Master Class:

Grid Connected Rooftop PV Systems

Dwipen Boruah

creating sustainable change through education, communication and leadership © 2012 GSES P/L creating sustainable change through education, communication and leadership © 2012 GSES P/L

Content

• Introduction to GSES

• Rooftop PV market - Growth and concerns

• Rooftop PV project development phases

• Site Assessment and Feasibility

• Design and Safety

• Operation and Maintenance


Introduction

PROJECTS & TRAININGS

Australia 1998

China

India - 2012

New Zealand

Asia PacificAfrica

Diverse and proven experience in both government and private enterprise in: • Renewable Energy engineering Design • Consultancy • Compliance audits & Due diligence • Clean energy education

Grid connected and off grid renewable energy, energy resources and the commercial aspects of Renewable Energy technology systems and power supplies.

EXPERTISE

PORTFOLIO

Training Publications Engineering Consulting


More information available at www.gses.in

creating sustainable change through education, communication and leadership © 2012 GSES P/L

ROOFTOP PV - GROWTH AND CONCERNS


Solar Power – status and target by 2022

2.12 10.3 37 941 1645 2632 3383 6763 9235

32000

48000

65000

82500

100000

0

20000

40000

60000

80000

100000

120000

FY 2008

-09

FY 2009

-10

FY 2010

-11

FY 2011

-12

FY 2012

-13

FY 2013

-14

FY 2014

-15

FY 2015

-16

FY 2016

-17 (u

ntil 31

.01.20

17)

FY 2017

-18

FY 2018

-19

FY 2019

-20

FY 2020

-21

FY 2021

-22

Installed Solar Capacity (MW) - status and target

Source: MNRE


Source: MNRE

0

2000

4000

6000

8000

10000

12000

14000

Mahara

shtra

Uttar P

radesh

Andhra

Pradesh

Tamil N

adu

Gujarat

Rajasth

an

Karnata

ka

Madhy

a Prad

esh

West Ben

gal

Punjab

Haryan

a Delh

i Biha

r

Odisha

Telang

ana

Jharkh

and

Kerala

Chhatt

isgarh

Jammu a

nd K

ashmir

Uttarak

hand

Assam

Dadra

and N

agar

Haveli

Goa

Puduc

herry

Himach

al Prad

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Daman

and D

iu

Megha

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Chand

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Manipu

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Tripura

Mizoram

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Arunach

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Sikkim

Andam

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bar Is

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Laksha

dweep

Sola

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wer

cap

acity

(MW

)

RTPV Target by 2022

Total Solar Target by 2022

State wise target


Cost trends and Grid parity


Defects & performance loss

Cause of Defects and Performance Losses in PV Power Plants

Japan follows similar tendency showing major faults at installation. Lack of JIS standard equivalent to IEC 62446 keeps non standardized inspection methods

• Over 1 GW • TÜV Rheinland Data • 200+ systems • inspected 2014 ~

Q1.2015

24 TÜV Rheinland Group

55%

25% 9%

5%

5% 1% Miscellaneous

Environmental influence

Installation faults

Product defects

Design, Documenation & planning faults

Maintenance

5

Risks influencing Mega Solar Plant Returns

Planning & Design

Construction Acceptance Operations Disposal

Provisional Final

TÜV Rheinland Group

“The land of rising risk?” – F. Martin, N. Morley [TÜV Rheinland]; PVTech 02/2015

Major Concern in Sustainable Growth


Component related defects

5

Risks influencing Mega Solar Plant Returns

Planning & Design

Construction Acceptance Operations Disposal

Provisional Final

TÜV Rheinland Group

“The land of rising risk?” – F. Martin, N. Morley [TÜV Rheinland]; PVTech 02/2015

Particularly Serious Defects in PV Power Plants in 2014 ~ Q1. 2015 – TÜV Rheinland Data

43%

21%

18% 7%

7%

4%

Modules

Cabling

Connection & distribution boxes

Inverter

Mounting structure

Transformer station

30 % of power plants show serious defects (incl. safety issues) or large number of issues

> 50 % of defects are caused by installation or planning errors

> 50 % of particularly serious defects are component related

Inspections at installation and construction will reduce failures on long term ! 27 TÜV Rheinland Group

Major Concern in Sustainable Growth


Rooftop PV project development phases

• Inception / concept – Identify a potential PV project

• Project model – Revenue based (PPA), Net / gross metering/captive use

• Site Assessment and feasibility - site survey, project capacity, project cost,

economic assessment

• EPC - Engineering design, Procurement Construction

• Operation and maintenance - Preventive maintenance, monitoring &

evaluation and troubleshooting


SITE ASSESSMENT AND FEASIBILITY


Objectives of Site Assessment

• Installation costs and timeline are minimized

• Maintenance costs are reduced

• System is safe and reliable

• Power plant generates maximum output at location

• Return on investment is high


Main tasks during site assessment

• Assess occupational health and safety requirement

• Determine PV array location and suitable area conducting shadow analysis

• Determine placement of PV arrays – row spacing

• Determine number of modules can be installed

• Determine suitable location for inverters and other electrical equipment

• Prepare site and system layout planning

• Identify cabling routes and therefore the required cable run distances

• Study of site parameters that likely to affect the design considerations











Site Assessment Tools

• Site survey format (questionnaire) • A Solar Pathfinder • A compass • A measuring tape/ digital distance meter • A camera • An angle measuring equipment • A notebook • A working partner





1. In case of RCC flat roof: Usable area for installation of solar modules, load bearing capacity, accessibility to the roof, building orientation

1. In case of pitched/ slanted roof: Roof orientation, roof tilt angle, roof material, roof age, roof structure – type, material, load bearing capacity, accessibility and convenience to work on the roof

1. Shadow analysis: Assess potential source for near and far shadow, shadow from trees and vegetation, shadow from other buildings, shadow from objects like overhead tanks, poles and pipes etc., shadow from natural landscape in hilly areas

2. General environment - amount of dust, industrial smoke, pollution etc. 3. Solar radiation and climate data (wind and temperature) 4. Grid connectivity – voltage level, distance, cable routing

Site survey questionnaire


Determine PV array location


• Free from shadow in all days of the year – Use solar path finder

• Access for array maintenance

• Provide ample space for air cooling

• Prevails aesthetic of the building or premises

• Not far from the charge controller/ inverter/ battery bank

• Protect array from theft and vandalism



Installation without shadow analysis






Shadow Analysis - Use Solar Pathfinder


//localhost/Users/Dwipen/Training PPTs/Videos/Pathfinder_Overview.mp4



Shadow Analysis - Use Solar Pathfinder


Hei

ght

Distance

Critical Angle

Shadow analysis – analysing sun position


𝑆ℎ𝑎𝑑𝑜𝑤 𝐿𝑒𝑛𝑔ℎ𝑡 = 𝐻𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑡ℎ𝑒 𝑜𝑏𝑗𝑒𝑐𝑡 𝑥 𝐶𝑜𝑠 (𝐴𝑧𝑖𝑚𝑢𝑡ℎ 𝐴𝑛𝑔𝑙𝑒

𝑇𝑎𝑛 (𝐴𝑙𝑡𝑖𝑡𝑢𝑑𝑒 𝐴𝑛𝑔𝑙𝑒


Sun Position at Chennai

Time 21st December 20th June Azim. Alt. Azim. Alt.

05:45 - - 67° 0° 06:00 - - 68° 3° 06:30 116° 0° 69° 10° 07:00 117° 7° 71° 16° 07:30 120° 13° 71° 23° 08:00 123° 20° 72° 30° 08:30 126° 26° 72° 37° 09:00 130° 32° 71° 44° 09:30 135° 37° 70° 51° 10:00 141° 42° 68° 57° 10:30 148° 47° 64° 64° 11:00 157° 50° 57° 70° 11:30 168° 52° 43° 76° 12:00 179° 53° 14° 79° 12:30 190° 53° 338° 79° 13:00 201° 51° 315° 74° 13:30 211° 48° 303° 68° 14:00 219° 44° 297° 62° 14:30 226° 39° 294° 55° 15:00 231° 34° 292° 49° 15:30 235° 28° 291° 42° 16:00 239° 22° 291° 35° 16:30 242° 16° 291° 28° 17:00 245° 10° 292° 21° 17:30 247° 3° 293° 14° 18:00 247° 0° 294° 7° 18:30 - - 295° 1° 18:45 - - 296° -3°

Shadow analysis – analysing sun position



Determining space between two rows

Row in the South Row in the North

Determine placement of PV array


Determining Array Capacity

• Availability of shadow free area

• Installation purpose and budget

• Government program and incentive guidelines

• State Electricity Regulation

• Distribution Transformer capacity

• Connected load


DESIGN AND SAFETY


PV System Design Requirements

1. Determine system capacity – area, budget, policy and regulation

2. PV array system configuration – matching of inverter & array

3. Mechanical design – thermal, wind loading, corrosion

4. Safety issues – Personnel and system safety

5. Selection / rating of electrical equipment

6. Operation and Maintenance – procedure and recommendations, support system

and infrastructure

7. Marking and Signage - Equipment marking, signs and labelling

8. Documentation : IEC 62446: Grid-Connected Photovoltaic Systems—Minimum

Requirements for System Documentation, Commissioning Tests and Inspection


Performance of Solar Modules

Efficiency and Performance of a PV module primarily depends on

• Solar Irradiance

• Operating Temperature

Cell Operating Temperature

For c-Si, changes is about 0.4 − 0.5% / 1°C variation in temperature away from STC.

There is almost a linear relationship between the variation in irradiance and variation of the short circuit current.


Calculating Cell Temperature

Under international standards all modules are tested the following standard test conditions (STC).

Cell temperature 25˚C Irradiance of 1000W/m2 Air mass of 1.5

Normal Operating Cell Temperature (NOCT) has the following reference conditions:

Ambient air temperature 20˚C Irradiance of 800W/m2

Where, S = insolation in W/m2 Where, S = insolation in , S = insolation in W/m2


Matching PV Array & Inverter

1. Matching of PV array to the voltage specification of an inverter

2. Matching of PV array to the inverter’s current rating

3. Matching of PV array to the inverter’s power rating


Example of Technical Specifications of Inverters






1. Matching of PV array minimum voltage to MPPT minimum input

2. Matching of PV array maximum voltage to inverter maximum DC input

3. Matching of PV array maximum current to MPPT maximum input current

4. Matching PV array maximum capacity to inverter maximum DC power input


1. Protection against electric shock • Equipotential bonding to avoid uneven potentials across an installation

• Functional earthing for electronic equipment

2. Protection against overcurrent

• Resulted from: earth faults or short circuits • Causes: Multiple parallel strings, external source, application circuit

4. Protection against overvoltage and effect of lightening

• PV array maximum voltage for minimum temperature • Rating of electrical equipment for PV array maximum voltage

System Protection


Protection against electric shock

You never know who’s going to wind up touching the exposed metal of your PV system


Protection against over current





PV String Overcurrent Protection:

As per IEC 62548: Design requirements for Photovoltaic (PV) arrays sizing Fault Current Protection is derived as below: Where: ISC-MOD = short circuit current of the module ITRIP = rated trip current of the fault current protection device


PV Array Maximum Voltage

• All protection devices are rated at “PV Array Maximum Voltage” • As per IEC 62548 PV Array Maximum Voltage is calculated:

1. Using the temperature coefficient given by the manufacturer

M = No. of modules in series

Protection against overvoltage


System Installation Min Voltage Rating per pole

Min Voltage Rating Overall

Non-earthed array with isolated inverter

0.5 x VMAX OC ARRAY V OC ARRAY

Earthed array with isolated inverter

V MAX OC ARRAY 2 x V MAX OC ARRAY

Non-earthed array with non-isolated inverter

V MAX OC ARRAY 2 x V MAX OC ARRAY

Earthed array with non-isolated inverter

NOT ALLOWED

Voltage Rating of Array Isolator


Preventing Arcing and Fire

TS 62548 © IEC:2013(E) – 57 –

Annex D (informative)

Arc fault detection and interruption in PV arrays

Unlike traditional electrical products PV modules and wiring do not have an overall enclosure to contain arcs and fires resulting from component or system faults. Many PV systems operate at d.c. voltages which are very capable of sustaining d.c. arcs.

There are three main categories of arcs in PV systems (refer to Figure D.1):

Series arc which may result from a faulty connection or a series break in wiring.

A parallel arc which may result as a partial short circuit between adjacent wiring which is at different potentials.

Arcs to earth which result from failure of insulation.

If an arc develops due to a fault in a PV array this can result in significant damage to the array and may also result in damage to adjacent wiring and building structures. The most serious arc is likely to be a parallel arc because of the energy that is available to feed this type of arc, especially when the arc is between the main PV array conductors. This standard requires double insulation on cables used in PV array wiring and because of this double insulation requirement parallel arcs are very unlikely unless caused as a result of significant insulation damage due to fire damage or severe mechanical damage to cables. The most likely type of arc to occur in a PV system is a series arc. This is because PV systems typically contain a very large number of series connections. Series arcs are generally able to be stopped quickly by removing the electrical load from the PV array. In the case of grid connected systems this can be accomplished easily by shutting down the inverter system. Parallel arcs are much more difficult to extinguish but are also much less likely to occur.

PV

Series arcs

Arcs to earth

Parallel arcs

PV

PV

PV

PV

PV

Figure D.1 – Examples of types of arcs in PV arrays

If a series arc is not extinguished quickly it may propagate to involve other conductors and produce parallel arcs. It is therefore desirable to have a method of detecting and interrupting arcs in PV systems quickly. A new standard has been developed by Underwriters Laboratories UL1699B: Photovoltaic (PV) DC Arc-Fault Circuit Protection and manufacturers are in the process of developing equipment to meet this standard. The purpose of the arc fault circuit protection equipment is to detect and discriminate accurately arcs in PV arrays and to take action to interrupt the arc.

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Hot spot can cause fire


Even a loose connection may cause fire


A damage in cable can cause fire


Fire in PV system can be devastating


Connecting solar modules


Signage

Examples of Signs


Signage

Examples of Signs


Signage

Examples of Signs


OPERATION AND MAINTENANCE


Preventive maintenance plan

Maintenance Work Frequency Ensure security of the power plant Day-to-day Cleaning of solar PV panels to free from dust and other dirt like bird’s dropping etc. Weekly

Monitor power generation and export Daily (Remotely) Keep the inverters clean to minimise the possibility of dust ingress. Quarterly Ensuring all electrical connections are kept clean and tight. Half-yearly

Check mechanical integrity of the array structure. Annually

Check all cabling for mechanical damage. Annually Check output voltage and current of each string of the array and compare to the expected output under the existing conditions. Annually

Check the operation of the PV array DC isolator Annually


Cleaning of modules


Cleaning of Module


Cleaning of modules

Safety of personnel: • String voltage + 700V DC is lethal

• Inspect array thoroughly for cracks, damage, loose connections before cleaning

• Cleaning personnel shall wear Personal Protective Equipment (PPE)

Cleaning time: • Recommended time - during low light conditions

• The best time - from dusk to dawn Quality of water: • De-ionized water

• Water should be of low mineral content with total hardness less than 75ppm

• Water with mineral content of more than 200ppm should NOT be used.


Cleaning of modules


Cleaning of modules


Cleaning of modules

Use of cleaning agent:

• A mild, non-abrasive, non-caustic detergent with deionized water may be used.

• Abrasive cleaners or de-greasers should not be used.

• Acid or alkali detergent must not be used.

Removing stubborn marks: • Stubborn dirt such as birds dropping, dead insects, tar etc.,

• Use a soft sponge, micro-fiber cloth or non-abrasive brush.

• Rinse the module immediately with plenty of water.

Water pressure: • Water pressure should not exceed 35 bar at the nozzle.


Cleaning of modules

Drying: • Modules should be dried after rinsing using a chamois or rubber wiper with a

plastic frame on an extension pole.

• Wipe the module surface from top to bottom to remove any residual water from

the module.

Water temperature: • Temperature of water used for cleaning should be same as ambient temperature

at the time of cleaning.

• Cleaning should be carried out when the modules are cool to avoid thermal

shock which can potentially cause cracks on the modules.


Essential Elements of Quality System

Quality of Hardware

Quality of Management


THANK YOU

Contact Details: GSES India Sustainable Energy Pvt. Ltd., F-7B, Pocket F, Okhla Industrial Area Phase 1, New Delhi - 110020, Phone: +91-11-40587622; Mobile: +91 9560550075 e-mail: [email protected]; www.gses.in

Documents

Grid Connected Rooftop PV Systems - Smart Cities India expo · Rooftop PV project development phases • Inception / concept – Identify a potential PV project • Project model