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How we assess new PV connectionsLi-Wen Yip
2015 UK Power Networks. All rights reserved
Context
2008 2009 2010 2011 2012 2013 2014 20150
50
100
150
200
250
300
350
UKPN G83 PV Connections
SPNLPNEPN
Year
Cum
ulati
ve M
W C
onne
cted
2015 UK Power Networks. All rights reserved
Improving how we assess new PV connections
Research(LV network monitoring)
Design assumptions
(derating, diversity, min load, no-load volts, harmonics)
Voltage rise assessment tools
(simple spreadsheet vs spreadsheet tool)
Records of existing generation(G83, FiT registers)
2015 UK Power Networks. All rights reserved
LV network monitoring
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
Generation CT
Data Logger(1min intervals)
Net Export CT
PV Inverter
Research
2015 UK Power Networks. All rights reserved
Derating: efficiency / insolation
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
Design Assumptions
Worst case for thermal constraints
Worst case for voltage constraints
SpikeSpike
2015 UK Power Networks. All rights reserved
Diversity: panel orientation
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
4kW panels and inverter
4kW panels / 3.5kW inverter(flat 6 hour peak)
Design Assumptions
2015 UK Power Networks. All rights reserved
Diversity: panel orientation
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
Design Assumptions
No diversity despite varying
panel orientations
2015 UK Power Networks. All rights reserved
Derating: on-site consumption
Source: “Residential consumer responsiveness to time-varying pricing: Low Carbon London Learning Lab Report A3”,
Figure 5.29, http://bit.ly/1Lhllf0
Design Assumptions
Minimum load200W
2015 UK Power Networks. All rights reserved
Other Assumptions
Source: “Residential consumer responsiveness to time-varying pricing: Low Carbon London Learning Lab Report A3”,
Figure 5.29, http://bit.ly/1Lhllf0
Design Assumptions
Condition Assumption if unknown
No-load voltage 248V
Unbalance – Urban 1.43 : 1 : 1
Unbalance – Rural 2 : 1 : 1
Harmonics Ignored
2015 UK Power Networks. All rights reserved
Simple Spreadsheet
𝐼= 𝑃√3𝑉
∆𝑉=𝐼𝑍
Voltage rise assessment tools
2015 UK Power Networks. All rights reserved
Spreadsheet Tool – Live DemoVoltage rise assessment tools
EDP 08-0160 Distributed Generation Voltag
2015 UK Power Networks. All rights reserved
FiT vs G83 Registers: ≤4kW
Sources: FiT Installation Register Aug 2015, UKPN G83 Register Oct 2015
Records of existing generation
Missing
Registered in Both
UKPN G83 Register
Ofgem FiT Register(UKPN MPANs)
0 50 100 150 200 250 300 350 400 450
163 MW
205 MW
225 MW
369 MW
Total capacity of ≤4kW installations (MW)
Only 41% have same rating (within 0.1kW)
2015 UK Power Networks. All rights reserved
Conclusions
Derating due to efficiency / insolation
For thermal constraints: possibly yesFor voltage constraints: possibly not
Diversity due to varying panel orientations
Potentially reduced or eliminated because of undersized inverters
Derating due to on-site consumption Allow 200W per customer
Voltage rise assessment tool Ask me for a demonstration / copy
Records of existing generation
G83 is incomplete and inaccurate.DNOs can request Ofgem’s FiT data with full MPANs.
Thank You
[email protected]/in/liwenyipLCNF T1 Closedown report: bit.ly/ukpn-pvtool-cdr