Energy Efficiency in Buildings Workshop
Building Integrated Photovoltaics
Active Systems:
Building Integrated
Photovoltaics - BiPV
Dr Mark Jentsch
Sustainable Energy Research Group, University of Southampton
www.energy.soton.ac.uk
m.jentsch@soton.ac.uk
~1 kWp
~100 kW
Forget about PV before you have thought about your car!
Mark Jentsch, University of Southampton
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Energy Efficiency in Buildings Workshop
Building Integrated Photovoltaics
Photovoltaics
‘Greenwash’ or
something
useful?
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Image source: www.solarcentury.com
Photovoltaics – The Issues
Temperature effect
Inverter
Short Circuit
Current - Isc
Module
Open Circuit
Voltage - Voc (-10)
Double insulation
Maximum Power
Voltage - Vmpp (+70)
Mismatch
Standard Test
Conditions
Cell type
Multi-functional
elements
Installation and
Operation Standards
Performance Ratio
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Mark Jentsch, University of Southampton
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Energy Efficiency in Buildings Workshop
Building Integrated Photovoltaics
Photovoltaics - Characteristics
Source: sharp-solar.com
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Photovoltaics – IV Curves
Source: sharp-solar.com
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Mark Jentsch, University of Southampton
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Energy Efficiency in Buildings Workshop
Building Integrated Photovoltaics
Photovoltaics
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Standard Test Conditions
(1000 W/m² irradiance
25 °C cell temp,
AM1.5 - equator)
String 4 x 188W modules
each module
Vmpp =24V
Voc =29.6V
Temperature coefficients
Pmax=-0.485 %/ °C
Voc = -0.104 V / °C
Isc=+0.053 % / °C
Design criteria
Pmax @ -10 °C, 1000W/m²
Voc @ -10 °C
Vmpp @ +75 °C
Voc @ -10 °C = (Voc @ STC) + (-10 - 25)·(-0.104)= 29.6 + 3.6 = 33.2 V
Vmpp @ +75 °C = (Voc @ STC) + (75 - 25)·(-0.104)= 24 - 5.2 = 18.8 V
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Photovoltaics
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Standard Test Conditions
(1000 W/m² irradiance
25 °C cell temp
AM1.5 - equator)
Normal Operating Cell Temperature (NOCT) = 48 °C
PNOCT = (100 – (48 - 25) · (0.485))/100 · 188 = 167W
Other losses:
Inverter efficiency, 92%
DC cable losses, 1%
DC module mismatch, 2%
Dust, 2%
Performance Ratio (PR)
Actual module yield = (STC rating) x (efficiency loss effects)
= (188) x 0.92 x 0.99 x 0.98 x 0.98 x (167/188) = (188) x 0.77 = 146 W
Mark Jentsch, University of Southampton
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Energy Efficiency in Buildings Workshop
Building Integrated Photovoltaics
Photovoltaics
PR = 0.77
Annual Yield = (kWp rating) x PR x (hours in year) x
(average continous irradiance / 1000)
London ~ 3000 Wh/m² day = 3 kWh/day
= (3 x 1000 x 3600)/(24 x 3600)
= (3000/24) = 125 W/m²
1kWp in London (9m²)
= 1 x 0.77 x 8760 x (125/1000) kWh per annum
=843 kWh per annum
RULE OF THUMB 800 kWh per kWp INSTALLED
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Photovoltaics
Athens (38 deg N)
Chicago (42 deg N)
Abu Dhabi (24 deg N)
London (53 deg N)
Mark Jentsch, University of Southampton
Kuala Lumpur (3 deg N)
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