PV Excel Designer & Installer 2 Day solar PV Excel Course for - - PDF document

6/3/20 1

PV Excel – Designer & Installer

2 Day solar PV Excel Course for Designers and Installers of PV systems PQRS Presented by Carel Ballack +27 82 322 2601 carel.ballack@pqrs.co.za

• Course rules

– Please switch off cell-phones – In case of emergencies, please make and take calls

• utside
• Tea at more or less 10:30 & 15:00

– 15 minutes each

• Lunch around 12:00-12:30

– 30 minutes

• FaciliVes

– Bathrooms

2

General Welcome

6/3/20 2

• Electricity is dangerous.
• The purpose of this training course is to promote the use of

solar, for both electrical & plumbing solar technologies.

• The instructors cannot be held liable for informaVon

presented; or the way in which informaVon has been interpreted through this; or any other training, markeVng or media plaZorm. Please read product instrucVons and comply to manufacturer recommendaVons

• Your feedback is important
• Please complete the feedback form.
• We trust that you will enjoy the course

3

Content Disclaimer & Feedback

• Presenter: Carel Ballack

– Electrician – Plumbing and gas. – Former Ombudsman for SESSA – Tenders, Project management, Electrical infrastructure, Repairs and maintenance. – Consultant – Training & development for energy sector

4

IntroducVon - Presenter

6/3/20 3

5

IntroducVon PQRS Reports

6/3/20 4

• Rubicon, ACDC, Ellies
• Allelec, Yingli
• TIA - Test Instruments Africa
• ABB, PLP, Dixon
• Schneider, Enel, Greensun
• Mustek
• Tesla

7

IntroducVon PQRS - Network

• Green Cape
• Western Cape Government
• Mangosuthu University of

Tech.

• Copper Development

Association

• SAAEA
• SAPVIA
• AREP

OrganisaVons InsVtuVons and associaVons

• Leonardo Energy - free online training for engineers (advanced)

hgp://www.leonardo-energy.org

• Assess and determine available solar irradiaVon at a specific venue

hgps://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

• For free training on energy efficiency: Easy to Moderate to Advanced

hgps://www.schneideruniversiVes.com/

• Free Book - Unlimited Energy – Describes how bageries work

hgp://www.victronenergy.com/upload/documents/Book-Energy-Unlimited-EN.pdf

• Free Maths & Science Mastery - Training PlaZorm

hgps://www.khanacademy.org/

• Calculate solar systems viability

hgp://www.retscreen.net

8

Supplementary free informaVon

6/3/20 5

PV Project Stages & Business OpportuniVes

• Identify

Funding model

• Consider

system size

• Consider

system Type

• Oversee

municipal requirements

• Essentially –

project sales & support.

Development

6/3/20 6

• 1. Operations
• 1. Monitoring

O & M (OperaVons and Maintenance)

5 10 15 20 25 30

4:50 AM 5:10 AM 5:30 AM 5:50 AM 6:10 AM 6:30 AM 6:50 AM 7:10 AM 7:30 AM 7:50 AM 8:10 AM 8:30 AM 8:50 AM 9:10 AM 9:30 AM 9:50 AM 10:10 AM 10:30 AM 10:50 AM 11:10 AM 11:30 AM 11:50 AM 12:10 PM 12:30 PM 12:50 PM 1:10 PM 1:30 PM 1:50 PM 2:10 PM 2:30 PM 2:50 PM 3:10 PM 3:30 PM 3:50 PM 4:10 PM 4:30 PM 4:50 PM 5:10 PM 5:30 PM 5:50 PM 6:10 PM

Current DC (Inverter 1) [A] Current DC (Inverter 2) [A] Current DC (Inverter 3) [A] Current DC (Inverter 4) [A] Current DC (Inverter 5) [A]

O & M (OperaVons and Maintenance)

• 1. Maintenance
• 1. Cleaning modules & inverters
• 2. Checking modules for visible defects
• 3. Check mounting structures for loose bolts and bi-

metallic corrosion

• 4. Check cables & terminations for wear and tear and

hot spots

• 5. Checking modules for hot spots & non-visible

defects

• 6. Finding faults – See next slides

6/3/20 7

• 1. Finding faults
• 1. Ultra violet light –
• nly works after

hours

O & M (OperaVons and Maintenance)

• 1. Finding faults
• 1. Infra red cameras – only works when

system works

O & M (OperaVons and Maintenance)

6/3/20 8

• 1. Finding faults
• 1. IV Curve Tests – Expensive testers but

thorough

O & M (OperaVons and Maintenance)

• Choosing the right technology for the applicaVon

– Solar water heaVng vs solar PV – SWH systems are also referred to as Solar Thermal Systems – Solar PV - Solar Photovoltaic

Technology selecVon

1000w/m2

Available IrradiaVon

400 - 700w/m2

Solar Thermal Efficiency

130 - 180w/m2

Solar PV Efficiency

6/3/20 9

Solar Water HeaVng vs Solar PV

18

Standard Bank Braamfontein

Hybrid 200m2 solar water heaVng system

Energy Efficiency

6/3/20 10

19

MTN Head Office Roodepoort

180℃1200kPa 330kW solar cooling system

Energy Efficiency

20

University of Pta

52 000 Liter 848m2 Solar water heaVng system

Energy Efficiency

6/3/20 11

21

BMW Rosslyn

90℃ 200m2 Solar water heaVng system

Energy Efficiency

22

Exstrata Elands mine

60 000 Liter 320m2 Solar water heaVng system

Energy Efficiency hgp://www.blackdotenergy.co.za

6/3/20 12

Only 4% of all issues can be prevented by simply “reading the instrucVons”, a further 95% can be prevented by understanding the instrucVons

23

Photos of faulty installaVons

Pr

24

How not to install a PV system

• No earth leakage
• Bagery stored in

ceiling +50’C

• No earthing
• Incorrect cable

terminaVon

• Wire sizing?

6/3/20 13

• We can see:

– Shade to the leu of the panel – Standard twin & earth used – Top leu cable going through the roof material

25

How not to install a PV system

26

How not to install a PV system

6/3/20 14

• Wood as a mounVng

structure(EVA - EC)

• Overlap & overhang(MP)

27

How not to install a PV system

28

Solar Panels can burn

6/3/20 15

• Not Vght enough.

Hoop Iron used to support Modules

29

Fivng modules

• Spacing of mounVng

structure

• Copper pipe used as

lugs

• Photo taken in

the Eastern Cape

30

Electrical safety and maintenance

• O & M
• Cleaning and access?

6/3/20 16

31

Solar Borehole with shading

32

Submersible cable

6/3/20 17

2kWp system Somerset West

Module mismatch in string inverter Module sizing should be equal. Performance severely affected

• Growing culture in SA to use opVmizers in
• rder to compensate for shading, hence

shading is deemed to be “acceptable”. O&M DomesVc environment do not buy into maintenance agreements, sell remote monitoring device in

• rder to monitor

performance periodically

12kWp System Kyalami

• MC4 couplers were cut and ferruled in
• rder to parallel modules

– Not recommended as this may negate module warrantees. – May affect

• O&M, tesVng & product

durability

SANS 10142-1 6.2.5.2 Once current-carrying capacity has been determined and correction factors had been considered, carry out voltage drop calculations to determine voltage drop which should be within the allowed 5 %. (very inefficient for PV systems)

Electrical InstallaVon Standard accepts 5% Good PV PracVce suggests 1-3% (volt drop)

6/3/20 18

30kWp system Franschoek

UnintenVonal shading Lack of knowledge Module life possibly affected by long term overheaVng of cells due to shading Row spacing inadequate, 12 x 300W modules producing 400W O&M Apart from design, this secVon

• f the installaVon can’t be

inspected or maintained with ease, consider leaving space to move between modules. No spacing between modules makes visual inspecVon difficult

250kWp system JHB

IntenVonal shading

The engineer involved in this project combined the same modules affected by shade into the same string Although deemed good from a design point of view. Could affect long term life & performance of cells / modules All shaded modules are part

• f the same string

O&M Neighboring construcVon site resulted in dust deposits which required regular cleaning. Increase frequency of visual inspecVon to ensure opVmum performance

6/3/20 19

500kWp system in Fourways

Ongoing maintenance

• No space for cleaning modules
• DB Board cb’s overheated &

tripped conVnuously

• Inverters overheated
• Conductors from panels to

inverter overheated 230m 6mm2

38

Program & Content Flow

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Off-Grid Moun5ng Structures

6/3/20 20

TradiVonal ConnecVon Normal Eskom InstallaVon “Grid-Tied” Solar system

Small Scale Embedded Generator

6/3/20 21

Off-Grid Solar System No connecVon to Eskom Grid Hybrid System CombinaVon of both

Huge Grey Area

6/3/20 22

• The latest panels that can generate power at night?

– Uhm . . . .

• Water bageries

– Uhm . . . .

• The best solar system

Have you heard of:

VS

• hgp://www.slideshare.net/Ennaoui/rd-roadmap-ennaoui

C-Si AbsorpVon

6/3/20 23

• The best inverter

– Service, applicaVon, spares, technical support

• The best solar Modules

– 3rd party test results vs “Tier 1”

• The best bageries

– Datasheets

• Latest Technology

– Breathe, relax, breathe some more.

• Contractors

– www.arepenergy.co.za, FREE P4 Solar Test

How do I find. . .

• Find the detail

– In system calculaVon – Paperwork / invoices / Quotes – Get references – Do Research – Visit other sites

• Phone a friend
• Phone another friend

– It’s only R100k – R200k and auer all; you can afford it.

QuotaVons

6/3/20 24

“no worries, no-one can see my roof”

Solar Geysers Solar PV 48

IrradiaVon

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

6/3/20 25

• (Photovoltaic)
• PV Power varies based on available insolaVon.
• This variaVon could be effected by changes in the

atmosphere, weather pagerns and seasonal changes.

• InsolaVon is defined as the amount of radiaVon

striking the earth

• Note the difference in the terms

– Irradiance : Intensity of Solar energy kW/m2 – InsolaVon : QuanVty of Solar energy kWh/m2

49

InsolaVon vs irradiance

Reference: Duffie Beckman 1991

50

The solar constant 1367W/m2 – World RadiaVon Centre ReflecVon, DeflecVon & AbsorpVon

6/3/20 26

51

• Peak Sun Hours are used to

calculate power generaVon of PV modules

• Peak Sun Hours can be calculated

by dividing annual sun hours by the number of days per year.

• e.g. 2000kWhrs/m2 divided by 365 =

5,47kWh/m2

• 5,47kWh/m2/day or 5470Wh/m2/

day

• Sun hours calculaVon
• PVSol
• PV Syst
• Helioscope

CalculaVon tools for design confirmaVon

6/3/20 27

• hgps://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP
• GHI - Global horizontal irradiaVon is used for PV

applicaVons

• DNI - Direct Normal irradiaVon figures are used for solar

Thermal applicaVons

• hgps://www.suncalc.org/

#/-30.8331,24.3049,2.5266666666666775/2019.07.30/14 :30/1/3

53

Link to GRS Solar Tool

Global Horizontal Irradiance (GHI) is the total amount of shortwave radiation received from above by a surface horizontal to the ground. This value is of particular interest to photovoltaic installations and includes both Direct Normal Irradiance (DNI) and Diffuse Horizontal Irradiance (DIF). 54

Incline

6/3/20 28

• Single axis trackers
• Implemented in SA
• Shows approx. 30%

improvement on yield

• Maintenance

should be considered in feasibility criteria

55

Trackers

Sishen 75MW Centurion Solar

56

Summer and winter solsVce

33o 43o 63o

6/3/20 29 2 4 6 8 10 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

57

Impact of incline on yield

53 53 33 33

58

Impact of incline on yield - JHB

2 4 5 7 9 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

23 33 43

33oCPT 33oJHB

6/3/20 30

hgp://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?map=africa

59

2000 4000 6000 8000 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Watts per day

Due North West & East South Due North 60’ Tilt

InsolaVon energy (Bfn 30o)

E N W

60

Summary - Impact of orientaVon

• 1000W/m2 is used

as the reference value and global average.

• Solar IrradiaVon

varies according to region and season.

6/3/20 31

• AC IS NOT COMPATIBLE WITH DC
• The frequency of AC in SA is around 50Hz meaning there are 50

‘waves’ or cycles per second

• To Convert

– AC to DC we use a RecVfier – DC to AC we use an Inverter

• Inverters invert DC to AC. By definiVon Inverters cannot charge

ba/eries

61

AC & DC

• Both inverters and recVfiers are sources of Harmonics
• Harmonics are caused by non-linear loads
• Pre-1970 all loads were linear as they were mostly resisVve
• The fundamental, is defined as the lowest frequency of a

periodic waveform

Harmonics

6/3/20 32

• Only some inverters can synchronise to a reference, i.e Grid Ved inverters

that feed power back to the grid

• MulVple sources of AC need to be synchronised, i.e. Voltage + Frequency +

Phase angle

63

AC & DC

With DC no synchronisaVon is required.

• DisVncVon between power and energy is important

– When sizing systems

• Energy requirement is used to size the bageries
• r storage devices
• Power requirement is used to size the inverter
• Understanding the difference gives the consumer

confidence in the knowledge of the sales and installaVon teams

Power and Energy

6/3/20 33

• Solar Modules are rated in Power Capacity
• Loads are rated in Power Capacity
• Li-ion Bageries generally rated in Energy Capacity
• Lead Acid bageries – Energy capacity must be calculated

65

Power and energy

• Example: Let’s take 12 LED downlighters from the

previous slide as the load

• Each downlighter consumes 23W
• 12 x 23W = 276W
• Energy = Power x Time
• Energy = 276W x Time
• Energy = 276W x 8hrs = 2208Wh or 2,2kWh

Power and energy - ConsumpVon

6/3/20 34

• As per the data sheets - Page B2 – ‘60 cell module’
• Energy = Power x Vme = 260W x 5,5hrs = 1430Wh
• Modules for a site is selected based on:

– Roof size – Module orientaVon – Stock availability – Price – Ease of on-site operaVon

Power and energy - GeneraVon

• Power can be calculated by multiplying Volts with Amps
• W = Volts x Amps
• Energy = Power x time or Wh = W x hrs
• Energy = (Volts x Amps) x hr
• When the energy in a Lead Acid battery is calculated the

Amp-hour rating of the battery is multiplied by the nominal Voltage

• Lead Acid Battery: Energy = Ah x V
• 100Ah x 12V = 1200Wh

Power and energy - Storage

6/3/20 35

• Energy = Power x time = 260W x 5,5hrs = 1430Wh
• Energy = 276W x 8hrs = 2208Wh or 2,2kWh
• Energy = Ah x V = 100Ah x 12V = 1200Wh

ConsumpVon – Storage - GeneraVon

• What is Volt?

– Voltage can be explained as being electrical pressure

• What is Amp?

– The movement of current is measured in Amps

• Nominal voltage
• What is Series? See next slide
• What is Parallel? See next slide

Basic Terminology

6/3/20 36

• Voltage increases and the current stays the same

Series configuraVon

• When connecVng in series the voltage is mulVplied by the number of panels to get to the

system voltage.

• The inverter or charge controller needs to be able to operate in the system voltage temp ranges

72

Series ConfiguraVon

Modules in Series Voc Ave. Per cell Module Voc

• 15℃

80℃ 36 Cell X 8 Modules 0,6 21,6 193 144 54 Cell X 8 Modules 0,6 32,4 290 216 60 Cell X 8 Modules 0,6 36 322 240 72 Cell X 8 Modules 0,6 43,2 387 288

Values are es5mated and have been calculated using a temp co-eff. of 0,30%/℃

6/3/20 37

• Current increases and the voltage stays the same

Parallel configuraVon

• Using Branch

connectors

• Same power being

produced as previous slide

• Lower Voltage
• Current X 2 of

a single string

74

Parallel ConfiguraVon

Modules in Series Voc Ave. Per cell Module Voc

• 15℃

80℃ 36 Cell X 4 Modules 0,6 21,6 96 72 54 Cell X 4 Modules 0,6 32,4 145 108 60 Cell X 4 Modules 0,6 36 161 120 72 Cell X 4 Modules 0,6 43,2 193 144

6/3/20 38

75

Parallel ConfiguraVon

• Using a combiner box
• Same power being produced

as previous slide

• Offers the advantage of
• individual string

disconnecVon

• Housing for SPD’s

To Inverter

• Ohm's Law is a formula or range of formulas used to

calculate the relaVonship between voltage, current and resistance in an electrical circuit.

Ohm’s Law

6/3/20 39

• The power Triangle is a range of formulas clarifying the

difference between Power, Current and Voltage

Power triangle System sizing when storage is included

6/3/20 40

• Batteries charge with current
• The current changes the internal resistance
• f the battery
• The result is an increase in voltage

How bageries charge

80

PV Technology

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

6/3/20 41

81

PV History

1839 - Edmund Becquerel discovers the photovoltaic effect 1883 - Charles Fritz creates first solar cell (gold coated selenium) 1953 - Bell labs create Solar Cells that are 6% efficient 1958 - Solar energy is used in space 1982 - First 1MW plant is built in California 1994 - NREL creates 30% efficient Gallium Indium phosphate 2015 - 5% eff. Flexible Solar cells are printed using a printer

82

Costs of PV over Vme

$0,38(US)

1MW CosVng around R13/w Oct 2016

2016

Freight 0,01 Profit Margin 0,02 Cell 0,20 BoM, EVA 0,12 Manufacturing & Assembly 0,04 Total 0,39

6/3/20 42

83

Basic Electrical Principles

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Off-Grid Moun5ng Structures

84

Different PV technologies

6/3/20 43

85

NREL PV Performance over Vme

General PV Module Efficiency

Cell Material Lab Actual Concentrated pv (Sharp May 2014) 47%

• Mono-crystalline silicon (Panasonic Feb 2014)

24.7% 18% Poly-crystalline silicon 20.4% 17% CdTe (Cadmium-Tellurid as at July 2015) 21.5% 16% CIGS (Copper Indium Gallium di Selenide July 2014) 18.3% 13% Amorphous Silicon (a-Si August 2014) 12% 10%

6/3/20 44

87

Crystalline Silicon Cells

Poly-crystalline Mono-crystalline

• Cells are approximately 0,2mm thick

88

Solar Cells

Busbars/ Ribbons Grid fingers

Do not stand on modules!!

6/3/20 45

• Ribbons or busbars are soldered onto the face of one cell.
• And then joined onto the back of the next cell
• One side of the cell has one polarity and the other side has the
• pposing polarity

Series cell configuraVon

90

16W Module - Cell configuraVon

Busbars/ Ribbons Grid fingers

6/3/20 46

• 36 Cells - TradiVonally

called 12 Volt modules

• 54 Cells
• 60 Cells
• 72 Cells - TradiVonally

called 24 Volt Modules

91

Solar Cells configuraVon

• Some modules consist of 5 layers
• Globally most module

manufacturers use 3.2mm tempered low-iron glass

• Hydrofobic & Hydrophilic coaVng
• AnV-reflecVve coaVngs
• AnV-dust / water
• Nano CoaVngs

92

Module ConstrucVon

• Hail tesVng done with 25mm hailstones at approx. 80km/h

6/3/20 47

• CIGS

– Solar FronVer moved out of SA in 2016

• CdTe

– First Solar Barloworld

• Material and workmanship warranty for ten (10) years

and a power output warranty of 90% of the nominal

• utput power raVng (PMPP+/- 5%) during the first ten

(10) years and 80% during twenty-five (25) years subject to the warranty terms and condiVons.

93

Thin-film - CIGS & CdTe

• Cell, module, string, array

94

Cell, Module, String, Array

1 x Cell 1 x Module 1 x String 1 x Array

Image is an example only Induced Voltages – Do not connect this way

6/3/20 48

• Voltage of cells remain more or less the same

at

• 0.5Voc(open circuit) to 0.7Voc(open circuit)
• Under varying temperature condiVons

95

• Current changes along with cell

size

• 100 x 100 cell = approximately

4.5Amp

• 150 x 150 cell = approximately

8.7Amp

PV Cell Electrical parameters

• Calculate the voltage of the string of cells

above?

96

• If the cells were 100 x 100, what would the

Current be that can be produced?

PV Cell Electrical parameters

6/3/20 49

97

Main PV technologies

Thin-Film

Major Issues (CIGS) DelaminaVon

Silicon wafers

Major Issues (Mono & Poly) Micro Cracks (snail trails) DelaminaVon

Thermal images: courtesy Sinani Energy

• Power output tolerances
• Cells vary in performance. SorVng limits relate to possible variances in panel

performance

• ISC

– The short-circuit current is the maximum current through the solar cell (i.e., when the solar cell is short circuited).

• Voc

– Open-circuit voltage is the difference of electrical potenVal between two terminals of a device when disconnected from any circuit. – There is no external load connected. – No external electric current flows between the terminals.

98

Understanding the Data Sheet

6/3/20 50

• STC corresponds to:
• 1000W/m2
• At 25°C cell temperature,
• with an Air Mass 1.5

(AM1.5),

• as defined in IEC 60904-3

99

All values in specificaVons are at STC & NOCT

NOCT is the temperature reached by open circuit cells in a module under the conditions as listed below:

• Open back mounted module
• At a 45° Vlt angle from the horizontal
• Total irradiance of 800 W/m2 and
• 20°C ambient temperature where a
• 1 m/s wind speed is available
• on a panel in an open circuit

condiVon

• One and a half Vmes the spectral absorbance of the Earth’s
• atmosphere. It refers to the amount of light that has to pass

through Earth’s atmosphere before it can hit Earth’s surface, and has to do mostly with the angle of the sun relaVve to a reference point on the earth.

100

Air Mass

• Modules used in space are

tested against AM=0 as the atmosphere is not a factor in space.

evaluaVng spectrally selecVve PV materials with respect to performance measured under varying natural and arVficial sources of light with various spectral distribuVons.

6/3/20 51

101

PV Panel DegradaVon

• Benjamin Franklin

– Glass & Silk Experiment – Kite experiment

• Electrons

– Charged ‘negaVve’ – Move from areas of abundance to areas of depleVon

• The same principles can be seen in solar modules

102

Electron Flow

6/3/20 52

103

Current flow in a cell - video

104

No Visible Diodes

By-Pass diodes in panels

Polarity: PosiVve is always on the right and negaVve always

• n the leu in crystalline

modules

6/3/20 53

• Most good quality panels are factory figed with Diodes.
• A diode can be explained as a one way valve for current.

105

How to overcome the effect of shading

• These diodes are

referred to as bypass diodes

• Bypass diodes do not

have an impact in reverse current

Long pins connected to negaVve Centre pin connected to posiVve Typical bypass diode wiring configuraVon

• Rule of thumb for panel installaVon in CT, EL &

PE= 1,9 X height

• Rule of thumb for panel installaVon in DBN &

BFN = 1,8 X height

• Rule of thumb for panel installaVon in JHB = 1,6

X height

106

Spacing of rows - rule of thumb

6/3/20 54

• IV characterisVcs show the current and voltage generated

across the terminals of a module.

• With a variable resistor connected between the terminals,

the operaVng point can be determined from the resulVng IV characterisVcs.

• When R is small the module is a constant current source
• When R = 0, Isc condiVons result. At Isc, voltage is 0
• When R is large (approaching infinity, modules behave as

a voltage source creaVng the max Voc. At Voc current is 0

107

IV Curves explained

108

Effect of temp. on PV panels

6/3/20 55

109

Hot vs Cold days - String Voltage

50 100 150 200 250 300 350 400 450 500 550 600 650 700 5 Jan 2016: Heat wave in summer. 15 Jun 2015: Coldest winters day. Max 660V Min 460V 20 modules in a string - 4 strings / mppt - 3 mppt’s per inverter

• ObjecVve: Calculate the module’s summer and winter voltages
• Summer Voltage is the lowest possible voltage at the highest

temperature

• Winter Voltage is the highest possible voltage at the lowest

temperature

Temp co-efficient calculaVons

Winter Summer Module Voltages are High Temperatures are low Module Voltages are Low Temperatures are high

6/3/20 56

• -0,45%/℃ 260W 60 cell
• Eff of temp = 30,9Vmp x 0,45%/℃
• = 0,139V

111

Temperature co-efficient calcs

23Vmp Actual Cell Temperature - Values based on resident survey 80℃ 25℃ 0℃

• 15℃

NC 70℃ GP STC PE & CT Molteno NC NOCT 46℃ ±2 Add co-efficient Deduct co-efficient 30,9Vmp 36Vmp 60+℃ CT EL 5℃ Maximum Voltage (VDC-max) = Vmp Max_STC (Solar PV) x 1.15 =Vmp Min_STC*0.75

12,500 25,000 37,500 50,000 62,500

8th January 2016 5th January 2016 4th May 2015

112

Sunny vs rainy days

Cloudy Summer : Produced 316kWh for the day. Clear Summer : Produced 386kWh for the day. Clear Winter : Produced 248kWh for the day.

6/3/20 57

113

Effect of Light intensity on current and voltage

114

Min & Max Current - Edge of cloud effect

A maximum value of 1195W/m2 was observed on 31/7/2015(PE)

6/3/20 58

115

Standards

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

116

Consumer point of supply

6/3/20 59

117

Dedicated Feeder NRS 097

< 75%

< 75%

• Maximum PV System sizes
• LSM > 7
• < 50 % conversion to PV
• Shared liability

118

Shared Feeder NRS 097

<25% < 25%

< 75%

6/3/20 60

119

Typical demand curve for residenVal installaVon

Evening Peak Demand

Morning Peak Demand

PV Power generaVon vs convenience

120

Inverter / system size selecVon

Mid day Peak Demand PV Power generaVon Typical demand curve for

• ffice block installaVon

6/3/20 61

• 1. Occupational Tasks
• 2. Planning and preparing for maintaining, testing, diagnosing, repairing and replacing PV system electrical

and mechanical components (Level 4)

• 3. Inspecting, testing, diagnosing, replacing and maintaining PV panels (Level 5)
• 4. Inspecting, testing, diagnosing, replacing, repairing and maintaining inverters in PV systems (Level 5)
• 5. Inspecting, testing, diagnosing, replacing and maintaining batteries and charge controllers and repairing

charge controllers in PV systems (NQF Level 5)

• 6. Inspecting, testing, diagnosing, replacing, repairing and maintaining transformers in PV systems (Level 5)
• 7. Inspecting, testing, diagnosing, replacing and maintaining cables, cable inter-connections, smart boxes, PV

junction/string boxes, string diodes, connectors and fuses in PV systems (Level 5)

• 8. Inspecting, testing, diagnosing, replacing, repairing and maintaining switchgear and control gear in PV

systems (Level 5)

121

Solar PV Service Technician(Separate Trade)

• Influx of diverse range of occupaVons in energy sector

– Many not skilled in electrical trade – RPL vs standard apprenVceship route – 4 years experience with >N2 Electrical – 6 years experience with no academic electrical background – Merseta, Ceta, EWseta – Same cerVficate & Red Seal – Register with D.o.L – = single phase tester – Electrical trade = N4 – Unlocks more opportuniVes, i.e. N4 electrical academic online

122

How do i qualify as an electrician

6/3/20 62

123

Legal, Standards & Regulatory Framework

• Commissioning report

– Installer tested system and it was working – Line diagram

• Should accompany design but could become as-built

– Standard operaVng procedure

• Manuals and documents

– Maintenance Procedure

• Improve overall performance (up-sale SLA)

– Lock out or disconnecVon procedure

• What happens when the system

– Stops working – Needs to be maintained – Electrical C.o.C

• NaVonal Regulator for Compulsory Standards

– Leger Of Authority

• SANS IEC 61010 - Safety requirements for electrical equipment for

measurement,control and laboratory use

• SANS IEC 61558 - Safety requirements for power transformers, power

supplies,reactors and similar products

• VC8075 - Compulsory SpecificaVon for the Safety of Electric Cables

with Extruded Solid Dielectric InsulaVon for Fixed InstallaVons (300/500V to 1900/3300V)

• VC8077 - Compulsory SpecificaVon for the Safety of Medium-Voltage

Electrical Cables.

124

Compulsory Standards related to solar

▪ LOA’s are required by all manufacturers and importers of

commodities that fall under the scope of the compulsory specifications prior, to the sale of the product.

6/3/20 63

125

Solar standards developed by UVliVes Eskom AMEU 277 177 NRS SANS ECB & ECA

• 4.2.7 Labelling
• 4.2.7.1 A label on the distribuVon board of the premises

where the embedded generator is

• connected, shall state: “ON-SITE EMBEDDED GENERATION

(EG) CONNECTED. THE EG IS

• FITTED WITH AN AUTOMATIC DISCONNECTION SWITCH

WHICH DISCONNECTS THE EG IN

• THE CASE OF UTILITY NETWORK DE-ENERGIZATION.”
• 4.2.7.2 The label shall be permanent, coloured red, and

with white legering of height at least 8 mm.

126

Labelling - NRS 097-2-1:2017

6/3/20 64

• 4.1.6.4 Total harmonic current distorVon shall be less than 5 % at

rated generator output in accordance with IEC 61727. Each individual harmonic shall be limited to the percentages listed in table 1.

127

Current distorVon limit as a funcVon of harmonics (Source: IEC 61727:2004) 1 2 Odd harmonics DistorVon limit 3rd through 9th Less than 4,0 % 11th through 15th Less than 2,0 % 17th through 21st Less than 1,5 % 23rd through 33rd Less than 0,6 % Even harmonics DistorVon limit 2nd through 8th Less than 1,0 % 10th through 32nd Less than 0,5 %

Harmonics - NRS 097-2-1:2010

• 4.1.1.6 The maximum size of the embedded generator is

limited to the raVng of the supply point on the premises.

• 4.1.1.7 Embedded generators larger than 13,8 kVA shall be

balanced three-phase type.

• A customer with a mulVphase connecVon shall split the

embedded generator over all phases if the EG is larger than 6 kW.

128

UVlity compaVbility – NRS 097-2-1:2017

6/3/20 65

• 4.1.8.2 AutomaVc synchronizaVon equipment shall be

the only method of synchronizaVon.

• 4.1.8.3 The limits for the synchronizing parameters for

each phase are

• a) frequency difference: 0,3 Hz,
• b) voltage difference: 5 % = 11,5 V per phase, and
• c) phase angle difference: 20°.

129

SynchronisaVon - NRS 097-2-1:2010

• hgp://resource.capetown.gov.za/documentcentre/Documents/Forms,%20noVces,

%20tariffs%20and%20lists/Approved%20Photovoltaic%20(PV)%20Inverter %20List.pdf

130

NRS Standards applied

• Product: KLNE
• Model: Solartec D15000
• Test House: TUV Rheinland
• Requirement: RCD Type B required on the supply side

6/3/20 66

131

Solar standards developed by Industry Eskom Technical Commigee ECB & ECA Industry associaVons Eskom Working Group ECB & ECA Industry associaVons SABS Specialist Reps.

• SANS 60364-7-712 (Fuse and cable sizing)
• SANS 61215 PV Module standard
• SANS 62040 UPS systems
• IEC 62930 Electric cables for photovoltaic systems (Feb 2018)
• Local standard development

– Same colour cable on DC – TesVng procedure on PV – AddiVonal DB – Surge protecVon before and auer – Level of electrician to sign-off bagery installaVons

• Hazardous locaVons

132

Standards issued or being developed

6/3/20 67

133

Bageries

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

• Both Lead-acid and Li-ion Bageries have C raVngs
• “C” indicates 3 important criteria.

– Energy Capacity – Charge rate – Discharge rate

C-RaVng of bageries

6/3/20 68

• Capacity of the bagery provides the

storage capacity of a bagery, e.g. 100Ah

• Bageries are usually marked as C10, C5,

C2, C1 or C0.5. The subscripts 10, 5, 2, 1

• r 0.5 gives the charge/discharge rate
• If we have a bagery denoted by C10,

having a capacity of 40 Ahr, then (40/10) = 4 Amps of current can be drawn from such a bagery for 10 hours.

135

Bagery Capacity

• Energy = Power x Time
• Power = Volt x Current

136

Cost of energy equaVon - Life cycle cost

Cost of Energy = Bagery Price (Energy(Ah*V) x DoD x #Cycles x Round trip efficiency) __________________________________ Cost of Energy (SMF) = R1200 (1,2kWh x 50% x 120 x 90%) __________________________________ Cost of Energy (SMF) = R18,52/kWh

6/3/20 69

• D.O.D

– Depth Of Discharge

D.o.D & RTE

• R.T.E

– Round Trip Efficiency

• Flow bageries
• Li-ion bageries
• Lead acid bageries
• Super capacitors

138

Four main storage technologies

6/3/20 70

139

Redox Vanadium Flow

hgp://www.cesa.org/webinars/showevent/flow-bagery-basics-part-1-what-they-are-how-they-work-where-they-re-used?d=2014-06-19

Performance not affected by temperature Can be drained 100% over full service life Life unlimited or 10 years Charge Voltage 54VDC System weight 1800kg - 3000kg 5 year standard warranty WxDxH 2.20 x 1.22 x 2.15 m 2,7m2

Li-ion Chemistries

6/3/20 71

Li-ion bagery layouts

• Lithium Iron Phosphate
• No significant heaVng during charging and discharging process.
• Larger bagery architecture.
• Lithium Iron NMC (Nickel Manganese Cobalt) Tesla
• Significant heaVng – Tesla - Water cooled system
• approx. 880 small bageries to create 48V packs stepped up to

400V(DC-DC Converter)

• 6,4kWh per day at a max of 3,3kW peak.(18MWh)
• Full closed loop recycling by 2020

142

Li-Fe Bagery technology

6/3/20 72

• Lead acid bageries are not an exact science

– The energy storage and draw-off is as a result of a chemical reacVon subjected to external factors

143

Lead Acid Family

Higher level of gassing & self discharge Requires higher charge voltage Calcium = Lower level of gassing

Lead Antimony Lead Calcium Lead Calcium Lead Calcium

Standard Maintenance Free Absorbed Glass Mat (AGM) Gel VLA (Vented Lead-Acid) Flooded VRLA (Valve Regulated) (Non Spillable) Lead Acid

**Tip -Compare weight

• Bageries have posiVve and

negaVve plates separated from

• ne another to prevent short

circuit condiVons. – Standard lead acid (car bagery)

• 2,2mm posiVve &
• 1,4mm negaVve plate
• Deep Cycle (brand dependent)
• 3,3mm posiVve &
• 2,3mm negaVve plate

144

Lead Acid ConstrucVon

Car bagery posiVve plate Deep cycle posiVve plate

6/3/20 73

• 12 Volt bagery = 6 x 2V cells

– Which always produce

• approx. 2,1 - 2,3 Volts/Cell

regardless of size of cell.

145

1 2 3 4 5 6

Lead Acid ConstrucVon

• 2 Volt bageries
• (photo: 1000Ah x 2V cells)
• Series & Parallel
• Bageries with a high power density and low energy density

– Good for delivering large volumes of power over a short period of Vme

• Good for vehicles

146

Bageries

• Bageries with a low power density and high energy

density – Good for delivering smaller volumes of energy over a longer period of Vme

• Good for solar
• Semi-TracVon Bageries (a happy medium)

– Good for delivering smaller volumes of energy over a longer period of Vme in light duty applicaVons

• Also referred to as “Leisure” Bageries

Car Leisure Deep Cycle

6/3/20 74

• Cycle life

– Number of cycles it was designed to deliver

• End of life

– A fully charged bagery that can only deliver 60-80% of its rated capacity may be considered to be at the end of its cycle life

• Design life

– See next slide

147

Bageries – D.o.D, End of life

• Bageries remaining in a floaVng state may or may not last

longer than bageries that are cycled

• When not in service all bageries self-discharge at a rate of

about 1-15% per month depending on the type of bagery.

148

Design life under float condiVons

6/3/20 75

149

Live fast die young

• Higher

temperatures = Lead acid bagery being more efficient

• Hoger bageries

die faster

• The rate of self-

discharge increases as the temperature increases.

150

Depth of Discharge vs Cycles

• If only cycled to 10% DOD, a bagery will last about 5 Vmes

as long as one cycled to 50%.

2000 4000 6000 8000 10000 12000 10 20 30 40 50 60 70 80 90 100 M-Solar Cell FNB Omnipower Trojan J185 Hoppecke OPzV Energizer Victron Li-ion

6/3/20 76

• Myth: Storing bageries on concrete floors will

cause them to discharge. – About 100 years ago, bagery cases were made up of wood and asphalt. The acid would leak from them, and form a slow- discharging circuit through the now acid- soaked and conducVve floor. – Wood is not used in modern bagery cases

• Bageries should not be placed directly onto

concrete during operaVon in order to prevent large temperature differences between the upper and lower regions.

151

Bageries - Storage

• Local landscape (Brands Available)
• SolarMD (MyPower24)
• Blue Nova
• Freedomwon
• i-G3N
• REVOV
• LG Chem
• BagCo.
• Icon
• Tesla
• BMZ
• Zegajoule
• Extra2000 (SolaX)
• Python (Pylontech)

152

Li-Fe Brands for Solar sector

• Li-ion bageries need to be managed

by a BMS in order to prevent thermal runaway and damage to the bagery

6/3/20 77

153

Lead Acid Charging cycle - 3 stages

Bulk AbsorbVon Float Time Voltage

Voltage Current

Bulk charge (aka constant current charge) Current stays constant and voltage increases Absorbtion Charge (aka Topping charge) Voltage remains constant and current drops consistently until battery is fully charged Float stage Charge voltage is reduced to between 13 & 13,8V and held constant while the current is reduced to less than 1% of battery capacity.

• Discharge takes place through the posiVve terminal
• Charging takes place through the negaVve terminal

154

Charging and discharge

VS.

6/3/20 78

• Recommended Charging current

– 10% of bagery capacity in Grid assisted areas – 20% of bagery capacity in certain off-grid areas – 30% of bagery capacity in all other off-grid areas

• (Sonnenschein) The charge current must not exceed 35A /

100 Ah nominal capacity. (35%)

• Higher currents will not lead to relevant gain of

recharging 9me. Lower currents will prolong the recharging Vme significantly.

• The cell / bloc temperature must never exceed 45°C. If it

does, stop charging or switch down to float charge to allow the temperature to decrease

155

Bagery charging

156

Why are these configuraVons incorrect?

Charging into the first row only Charging cable lengths EqualizaVon

6/3/20 79

157

Correct InstallaVon

Charging & discharging across bank Equal cable lengths EqualizaVon taken care of with busbars Why 12 / 24 / 48V Show series & parallel

158

Busbar & Disconnector Layout

6/3/20 80

• Bus bar calculaVon as a rule of thumb
• width x height x 2 should = bagery capacity
• 5mm x 20mm x 2 should be sufficient for a 200Ah bagery bank.
• (SANS10142-1 6.6.2) for current >1600A = 1,6A per mm2
• current <1600A = 2Amps per mm2

159

Bus bar calculaVon - Rule of thumb

Please double check busbar thickness for safety & applicaVon

Bagery charging

• Very important for background sevngs.
• Adjust the cable resistance in order to ensure the correct

charging voltage.

• (grid Ved hybrid inverters) Some can be controlled not to

feed back into the grid (Grid-LimiVng)

• AddiVonal equipment
• Meter
• Modbus
• costs about R4k

6/3/20 81

• Minimize voltage drop
• Use the correct size cables
• Locate bagery and load close to PV panel
• Choose a large enough bagery to store all available PV

current

• VenVlate or keep bagery cool, respecVvely, to minimize

storage losses and to minimize loss of life

• The 744 rule: Is a genset/grid available for boost charge ?

161

Bagery - Summary

162

Off-grid

PV technologies Irradia5on Series and parallel config Cable calc. Charge controller

DC Disconnect

Volt drop Inverter Voltage Calcula5ons BaHeries

Pr

Moun5ng Structures

6/3/20 82

System sizing when storage is included

164

Step 1 - Calculate consumpVon

Step 1.b) Daily ConsumpVon in Wh Step 1.a) Power Requirement in W

6/3/20 83

• Lead Acid System Losses vary

between ±22 to 30%

• Li-ion System Losses vary between

±18 to 22%

• hgp://www.bagerysizingcalculator.com

165

Step 2 - Bagery Sizing

Inverters 5 5 2 15

Inverter Charge controller Cabling System (Batteries + connections)

Step 2.a) Multiply Daily requirement with losses (as a factor) = 7994Wh x 1,27 = 10152Wh Daily Storage required Step 2.b) Divide Daily storage by DC voltage = 10152Wh / 48V = 211Ah of Average Daily Ah needed Step 2.c) Adjust to depth of discharge = 211Ah / 0,5 = 422Ah Sub Total of storage required

166

Bagery Sizing – Lead Acid

This value represents 27% Losses The “48V” value is found in the datasheet Step 1.a showed us we need 3576W of Power. At least a 5000W inverter would be required. From the datasheet Page B1, we will see the 5000W inverter uses a 48V bagery / bagery bank. Use 0,5 for 50% D.o.D, 0,4 for 40% D.o.D and so on . . . . .

6/3/20 84

Step 2.d) Make provision for rainy days =422Ah x 2 days = 844Ah Total Storage required The battery bank needs to be 48V 844Ah according to our calculations. Step 2.e) Select battery to match both both 48V and 844Ah as close as possible.

167

Bagery Sizing – Lead Acid

This value is just a guess and would vary based on the number of rainy days for that area

2 Volt Cell 840Ah 12 Volt Bagery 200Ah 4 in series to reach 48V 200Ah 24 in series to reach 48V 840Ah Step 2.f) Check to ensure that the chosen battery can handle the rate of discharge (c-rating) Step 3.a) Calculate Power required to charge batteries. (Group Exercise) Power = Volts x Amps Step 3.b) Select modules to match Power Requirement, roof space and ease

• f handling (Group Exercise)

Step 3.c) Module layout and design is done according to charge controller power, voltage and current limitations. (Group Exercise)

168

Bagery Sizing – Lead Acid

6/3/20 85

• Microcare vs Victron recommended chart
• Please check other manufacturer specificaVons

169

Step 4 - Select Charge Controller

170

Bagery Fuse calc’s

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

6/3/20 86

• The short circuit current of a bagery (considered to be a finite power

source) depends on: – the resistance of the path, and – the state of charge and – internal resistance of the bagery which depends on variables, such as:

• the material and dimensions of the grids and terminal posts,
• the surface area and composiVon of acVve material,
• the specific gravity, and
• the thickness of the separators
• REf : StaVonary Bagery and DC Power System Electrical ProtecVon Design

ConsideraVons; K. Uhlir

171

Bagery SCC

• The prospecVve short-circuit current of bageries can be calculated using

the following values in a formula: (I=V/R)

• EB is the open-circuit voltage of the bageries; if this informaVon is not

known, then use

• EB = 1,05 x UNB V (where UNB = 2,0 V/cell);
• RBBr is the total resistance of the upstream network, in ohms, including the

internal resistance of the bagery and the resistance of the conductors;

• RBBr = 0,9 x RB + RBL + Ry Ω (see figure 8.1);
• RB is the internal resistance of the bagery;
• RBL is the resistance of the bagery connecVons;
• Ry is the resistance of the conductors.
• NOTE The internal resistance of the bagery can be obtained from the

manufacturer’s data.

172

Bagery PSSC SANS 10142-1:2012

6/3/20 87

• A conservaVve approach in determining the short-circuit

current that the bagery will deliver at 25°C is to assume that the maximum available short-circuit current is 10 Vmes the 1 minute ampere raVng (to 1.75 V per cell at 25°C and specific gravity of 1.215) of the bagery

• Ref:hHps:www0.bnl.gov/isd/documents/88634.pdf
• Page 10 Sec5on BaHeries

173

Bagery PSCC

10 X 38 PV fuse

• Varied Philosophies on fuse sizing

– Could be based on:

• RecommendaVon by Manufacturer, or;
• Calculated based on current consumpVon, and
• n potenVal short circuit current, or;
• Various rules of thumb.

174

Bagery Fuses

6/3/20 88

230W @ 230V = 1A

175

Basic bagery discharge principles

230W @ 48V = 4,79A + Losses 48 Volt Battery Bank Inverter

I = __ P V

TV

176

Cable sizing for bageries - 0.259V drop max.

6/3/20 89

177

Conductors

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

• InternaVonal Annealed Copper Standard (IACS)

Metal / Material Conductance IACS Silver 105% Copper 100% Gold 70% Aluminium 61% Brass 28% Zinc 27% Nickel 22% Iron 17% Iron 17% Tin 15% Phosphor Bronze 15% Lead 7% Nickel Aluminium Bronze 7% Steel 3 to 15%

178

Conductor resistance

6/3/20 90

• Solid wire is cheaper, but does not put up with the constant flexing of

power cords.

• Solid core wire in our walls where it does not need to move and cost

magers

• Stranded wire in our power cords where a solid wire would quickly

harden and break from conVnuous flexing.

• Why would wire work harden, embrigle and break?
• Strand diameter relaVve to the bend radius is what determines how

much strain is imparted into the wire. Solid wires have large strand diameters and see lots of strain. Stranded wires have strands with small diameters.

• Welding & bagery cables use thin strands to compensate for movement

179

Solid or stranded?

• General Cable
• Halogen-free wiring will typically have

a higher conVnuous use temperature raVng, and is more suitable for pv

• peraVng environments.(Popular sizes

4 & 6mm)

• Rated from 900 – 1500V
• Flexible Vnned mulV stranded wire

180

Solar cable & conductors

Crosslinked Special Polyolefin

• XLPO
• 36 Shore D
• Halogen free
• Weather- and UV-resistant
• Ozone resistant

6/3/20 91

181

Avoid loops - Induced voltages

182

TerminaVng Solar cable

• MC4 type connectors are rated
• 22A-30A 4mm2-6mm2(please check parVcular brand)
• For safety reasons do not cross mate coupler brands
• Use only PV cerVfied cables (Vnned mulV-stranded,

double insulated)

• Avoid colour cables (long term UV resistance)

6/3/20 92

183

ConnecVng solar Cable

• AssumpVons & Figures correspond to SANS 10142-1 Page 305 & table 6.2

184

Volt drop CalculaVon

Convert from mV to Volts. Max distance = 20m @ 110V

• 4mm cable volt drop

= 11mV/a/m

• 6mm cable volt drop

= 7.3mV/a/m

6/3/20 93

185

Combiner boxes

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

6/3/20 94

• Black cable only in a DC network. Is it allowed?

187

AC & DC Combiner boxes

188

Combiner boxes – Examples

6/3/20 95

• Combine mulVple

strings in parallel

• Design is based on

– Inverter requirements – Site/safety requirements – Designer/ client preference

189

Combiner boxes – DC Combiner

• Combine

mulVple inverters onto the same AC connecVon point

• Design is site /

client / safety and applicaVon specific

• Moulded case

breakers recommended for commercial installaVons

AC Combiner boxes

6/3/20 96

• Tip **BT Consult conducted a study to

determine the temperature inside housings for electrical equipment. Findings were that internal housing temperature was between 8-10oC higher than outside ambient

• temperature. This value has reference

to the fuse deraVng temperature as per the next slide.

• Tip **Use molded case breakers in

larger systems

• Trend *Use fuse box opposed to a

combiner box on installaVons where the inverter comes figed with a combiner box

191

Tips & Trends

192

Fuse deraVng

▪ Fuse calculations: ▪ Isc x 1,56 ▪ Edge of cloud ▪ Fuse Derating ▪ 1 string not required ▪ 2 string not required ▪ 3 string maybe ▪ 4 string yes ▪ (n-1)Isc * 1,25

6/3/20 97

• Capability of the fuse should

be

• Where
• Voc = Open Circuit

Voltage

• Ns = Number of modules

in a string

• Fuse Voltage Capability
• = 1,2 x Voc x Ns
• Current Capability
• = 1,56 x Isc

193

CalculaVng String fuses

194

Earthing, LPS & SPD’s

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

6/3/20 98

• The simple definiVon of an earth is:
• to connect the electric circuit
• r equipment to the earth’s

conducVve surface.

• Systems are earthed because of:
• personal safety and

protecVon in the event of accidental contact

• equipment safety and

protecVon in the case of a lighVng strike, surge and

• r fault condiVons.

195

Earthing / Grounding

196

Surge protecVon without LPS (62305)

Class 2 Class 2

6/3/20 99

197

Surge ProtecVon with LPS

Class 2 Class 2

198

Class 1&2 Class 1&2

Surge ProtecVon with LPS

6/3/20 100

199

AC vs DC Switching

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures

• Fuse Wire / Fuses –

Melt or disintegrate

• Circuit breakers

– Can be reset – Do not use a CB with an AC raVng

• n a DC Circuit

200

Breaking the current

6/3/20 101

• Difference between AC & DC CB’s

– How they exVnguish an arc

• Arc chutes may be spaced further apart.

– Whenever a load is connected and disconnected, an arc is produced. – The arc generated in DC is much larger than AC. – AC Breakers not rated for DC will fail in a DC network – Technical term is ‘spark gap technology’

201

Circuit breakers

202

The difference in breaking AC & DC - video

6/3/20 102

• Electrical arcs produce some of the highest temperatures known to occur
• n earth, up to 19426oC
• Arcs spray molten droplets of metal at speeds that exceed 1120km/h

which can easily penetrate the body.

• Fatal burns can occur even more than a meter away with clothing being

ignited up to 3 meters away.

• The arc blast can have a sound magnitude of 140dB at a distance of 60cm

from the arc resulVng in hearing loss.

• Arc flash can be caused by something as simple as a rodent, tool or other

element in the breaker area which compromises the distance between energized components,

• 2 out of 3 electrical injuries are the result of inappropriate acVon of a

worker.

203

Arc Flashes

• MPPT’s can be added to increase charging capacity

204

Bi DirecVonal Chargers

• Courtesy suncolect.com

6/3/20 103

• Bi-direcVonal

charging

• 2 x 5kW

Axpert inverters paralleled

• Master vs

slave config

205

Bi-direcVonal chargers

• What is the maximum AC

current that can be pushed through the MulVplus?

• In this config, the Inverter will

keep the loads switched on.

206

AC Coupled Grid Ved inverter

Main DB

• The purpose of

connecVng a system in this way is for the mulVplus to provide a reference voltage to keep the grid Ved inverter switched on

• Transfer switch
• 2kW - 30A
• 3kW - 50A
• 5kW - 100A

6/3/20 104

207

Support Structures

PV technologies Irradia5on Series and parallel config Cable calc. Combiner Boxes PV Fuse calc SPD’s, LPS & Earthing DC vs AC Disconnect Volt drop Inverter Voltage Calcula5ons BaHeries Standards Energy Efficiency

Pr

Safety & Cos5ng Off-Grid Moun5ng Structures Moun5ng Structures

8 month old installaVon - JHB

208

Bi-Metallic reacVons

6/3/20 105

209

PowAsnap - ARaymond - Video

210

• Pitched

roof structural support

• Video by

Solarworld

Structural support and fitment

6/3/20 106

211

Only in the Northern Cape

• Earthing SecVon:
• hgp://www.nla.org.za/webfiles/conferences/2012/Papers/Monday,%203%20September/M206%20-%20High%20voltage%20pylon%20earth%20measurements.pdf
• hgp://www.ijser.org/researchpaper%5CSOIL-RESISTIVITY-AND-SOIL-pH-PROFILE-INVESTIGATION-A-CASE-STUDY-OF-DELTA-STATE-UNIVERSITY-FACULTY-OF-

ENGINEERING-COMPLEX.pdf

• www.copper.org
• hgp://electrical-engineering-portal.com/how-to-determine-correct-number-of-earthing-electrodes-strips-plates-and-pipes-part-1
• hgp://www.solarabcs.org/about/publicaVons/reports/module-grounding/pdfs/IssuesRecomm_Grounding2_studyreport.pdf
• Bypass diodes SecVon
• hgp://www.V.com/lit/ds/symlink/sm74611.pdf
• hgp://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/technical-literature/bus-ele-an-10191-pv-app-guide.pdf
• hgp://www.solar-facts.com/panels/panel-diodes.php
• Bageries
• hgp://fortune.com/2015/05/18/tesla-grid-bageries-chemistry/
• PV Fuse selecVon SecVon:
• hgp://solar.org.au/papers/08papers/408.pdf
• hgp://www.bre.co.uk/filelibrary/pdf/rpts/Guide_to_the_installaVon_of_PV_systems_2nd_EdiVon.pdf
• hgp://www1.cooperbussmann.com/pdf/4897c8Ü-c785-4993-a4d6-1fddf120cf70.pdf

212

References

6/3/20 107

THE END THANK YOU!! (Please see supplemental slides)

213