Session 5 - PV Research at Northumbria University Putting PV Into Practice Presented by Nicola...

8/7/2019 Session 5 - PV Research at Northumbria University Putting PV Into Practice Presented by Nicola Pearsall

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PV Research atNorthumbria

University:Putting PV into

Practice

Prof. Nicola Pearsall

Northumbria Photovoltaics Applications Centre (NPAC)School of Computing, Engineering and Information

SciencesNorthumbria University

Solar Flair 0919 November2009


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Putting PV into Practice Activities at NPAC

PV cell development NPAC works on new semiconductor materials within the

Supergen project

Transfer of technology to production

We are involved in environmental impact assessment to assistin defining the route to sustainable module production withEuropean industry

Maximising system performance NPAC undertakes system performance analysis and is

currently leading the work on updating the Europeanmonitoring guidelines

Integrating into a smart electricity grid Our power group considers the integration of renewable

energy into the grid distribution network



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ATHLET is an EC funded integrated project looking at thin filmphotovoltaics (based on silicon and chalcopyrite materials) being

undertaken by a consortium of European research institutes and industries NPAC considers the environmental impact of the processes being

developed in this project

For a renewable energy supply technology, it is important to consider thebalance of energy input to energy output and the emissions arising fromthe production process

We have developed a methodology for applying environmental impactassessment to help decision making in regard to research directions - thiscomplements decisions made in regard to potential technical andeconomic advances

We have considered cumulative energy demand, global warming potential,emission of particulates, acidification potential etc.

In most cases, the process energy is the dominant source of impacts dueto the assumption of a conventional energy mix

Assessing Sustainability in the ATHLET Project



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Methodology for Environmental Impact Assessment inResearch Planning

Most published environmental assessments of PV use establishedproduction processes and are carried out for:

Comparison of the impact of PV with that of other electricity generationtechnologies

Comparison of the impact of different PV module technologies

Three main differences can be identified when using EIA for research and

development purposes: The process may not be fully proven and so the process parameters may vary

we use ranges of parameters to understand the sensitivity to each parameter

The scale of the process is small and must be increased to consider productionlevel the parameter ranges are selected to be representative of knownproduction processes

The balance of the production sequence may not have been previouslyassessed - the change in environmental impact assessed as a function of thechange in performance resulting from the new process

Assessing Sustainability in the ATHLET Project



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PV in Practice some observations about

use

in the built environment PV is an elegant solution for the renewable generation of electricitywithin the built environment

It is technically proven many systems exist around the world and

are working well

The challenge is financial, but new UK feed-in tariffs will alter thesituation and make it much more attractive

From the design viewpoint, it does not require any increase in landuse and only needs minor amendments to building design

From the user viewpoint, it requires little attention and is notdisruptive in terms of noise or emissions

Like most renewable technologies, it will need to be used inconjunction with other energy sources to meet demand fully

However, we do need to learn how to use it to maximum advantage



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A Real Example: UK PV DomesticField Trial

The UK Domestic PV Systems Field Trial

(DFT) commenced in 2000 and was fundedby the UK Department of Trade andIndustry

Undertaken by project teams comprisinghouse builders, housing associations, PVcompanies, electricity companies etc.

Clusters of 5 31 systems on each site,usually of similar design and so allowingdirect comparisons between systems

Total of 28 sites and 474 systems, typicalsystem size 1-2 kWp

NPAC undertook the performance analysisfor all the systems


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Domestic Field Trial Sites

15 new build, 12refurbishment, 1 combined

Mostly brownfield sites

Range of house andapartment type, ownership(public and private),module type andintegration method

Systems were monitored fortwo years after installationto determine performanceand contribution to thehouse electricity demand

Analyses use different datasets depending on thequality of the data

The DFT also consideredbuildability, reliability andmaintenance, acceptabilityand user satisfaction



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Measured Annual Yield 358 systems, 24 sites(average system size = 1.6 kWp, average daily irradiation = 2.7

kWh/m2)



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Annual Solar Fraction 303 systems, 21 sites(average system size = 1.6 kWp)

Average SF is 50%



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Observed loss mechanisms

Inverter Faults

Trips due to e.g. voltage spikes

Threshold

Periods of outage due to high grid voltage

Failure to restart after deliberate shutdown

Array temperature due to poor ventilation of the modules

Shading Trees and other vegetation (often characterised by

increasing effect year on year)

Nearby buildings

Self-shading (i.e. by part of the same building)



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Example of Inverter Drop-out


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The System Deployment Challenge

Technologists develop

new PV cells Increase efficiency,

reduce materialsusage, reduce cost

Transfer technology tomodule production

Fabricate andmeasure under

controlled conditionsSYSTEM DESIGNER



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The system designer

selects the location, thecomponents and theinstallation methods

Losses are minimised

within the constraints ofthe application

The output is predictedover the lifetime of the

system

W/m2?

kWh/k

Wp?

Shading?

USER



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The Users

Want an easy, highoutput, low effortsystem

Are not expert insolar systems andhow they operate

Now, theprofessionals areno longer incontrol!



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Maximising Operational Performance

PV is a very reliable technology but any problems that do occur areoften observed in operation rather than at installation

Need engagement of users to be able to identify losses and rectifythem rapidly

User needs to understand how issues such as shading can developduring the system lifetime

NPAC is currently involved in the European project PERFORMANCE andleading the study of monitoring of PV systems over their lifetime so asto be able to pick up losses that might occur

The European PV Monitoring Guidelines are being updated to includelifetime monitoring and state-of-the-art monitoring and analysisprocedures

Customised guidelines will be available for each user category



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Establishing Probability of Loss

Long term monitoring (measurement and analysis) can

be considered as an insurance against substantiallosses in energy output due to system faults

The amount of money spent on monitoring should beproportional to the potential loss that may be incurred ifthere is no monitoring

The potential loss is related to the probability ofparticular failure modes as a function of time, systemtype, system size etc.

We carried out a Failure Mode Effects Analysis (FMEA) forthe monitoring process to establish which faults are the

most important and how to identify them Experts from industry and academia with direct field

experience were consulted for this process



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Monitoring Guidelines Delivery Approach

Setting the guidelines:The measurement and analysis requirements havebeen considered for a wide range of users, based on field experience oftypical loss mechanisms

Preparing the puzzle:The requirements are turned into sets of axioms for PVmonitoring (based on existing JRC Guidelines and IEC 61724 standard butmodified and added to according to the project results)

Preparing the identification interface: A set of key questions has been

defined the user questionnaire to allow the user category to be defined

Selection rule - Guidelines genetic code: A string of numbers is producedaccording to the answers to the questionnaire. Each axiom has a pre-defined code/string and is selected as appropriate to make up the finalguidelines



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Performance Analysis

The new guidelines also include an extended section on

analysis of the monitoring data For example, there is guidance on using comparison

between parts of the system or between similar systems toidentify when and where you have a problem

Most of the analysis for grid connected systems is based on

the performance ratio which allows us to set a target value

For stand alone systems, there are some new approachesinvolving the battery index (relating to how much of thetime the battery is fully charged)

It is important to have rapid and consistent fault diagnosisand that it is as informative in regard to severity, locationand cause as possible



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Janu

ary

Ma

rch

M

ay

July

Septem

ber

Novem

ber

00:00:00

02:00:00

04:00:00

06:00:00

08:00:00

10:00:00

12:00:00

14:00:00

16:00:00

18:00:00

20:00:00

22:00:00

80-90

70-80

60-70

50-60

40-50

30-40

20-30

10-20

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Example of AnalysisMethod(cont.)

Performance ratio contour plot forUK domestic system with outputreduction in summer months

Clear performance problems timing pattern gives some cluesas to the cause but furtherinvestigation needed



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Summary

NPAC is working on both PV device development and the

issues that arise from putting PV into practice This has been illustrated with examples of three projects,

either ongoing or recently completed

As new technology is developed, we will need to addresshow it can be used in practice and make sure that the

maximum benefit is gained in both energy andenvironmental terms


Contact:

[email protected]

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