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Solar power analysedA close lock into 5 years of operation of a small
residential PV-system !!!!!!!!
brought to you by goMicromorph PV-School
Energy Yield of a PV-systemEn
ergy
(kW
h)
0
400
800
1200
1600
2000
2008 2009 2010 2011 2012 2013
Average Annual Energy Annual Energy (kWh)
1'6531'644
1'878
1'4791'6031'564
Annual specific yield
Ener
gy (k
Wh)
0
400
800
1200
1600
2000
2008 2009 2010 2011 2012 2013
Average Annual EnergyAnnual Energy (kWh)
1'6531'6441'878
1'4791'6031'564
Formula 1:!Specific Yield = energy yield / nominal solar power !Example:!A PV-system of 1.5 kWPeak installed power (6 modules à 250 W) generates in a good year 1800 kWh of electricity. a) calculate the annual specific yield. b) calculate the average monthly specific
yield. Solutions: a) Ya = 1800 kWh / 1.5 kWp
Ya = 1200 kWh/kWp = 1200 h/a b) Ym = Ya / 12 = 100 h/m
The most meaningful figure of a solarPV system is the specific yield, indicating the energy per installed power - or the number of full operation hours per year or per month.
Annual specific yield
Ener
gy (k
Wh)
0
400
800
1200
1600
2000
2008 2009 2010 2011 2012 2013
Average Annual EnergyAnnual Energy (kWh)
1'6531'6441'878
1'4791'6031'564
Nominal PV power: Pg = 1.5 kWPeak Installed: 2007 Thin-film silicon (aSi) modules, new micromorph modules installed 2012 New nominal power: Pg = 2 kWPeak
Specific Yield (kWh/kWp)Ya 1043 1069 986 1252 1096 827
Pg! 1.5 1.5 1.5 1.5 1.5 2.0
Monthly energy yieldsSp
ecifi
c Yi
eld
(kW
h/kW
p)
0
45
90
135
180
1 2 3 4 5 6 7 8 9 10 11 12
Spec.Yield 2010 Spec.Yield 2011 Spec.Yield 2012 Spec.Yield 2013 Average Spec.Yield 2009
Monthly energy yieldsSp
ecifi
c Yi
eld
(kW
h/kW
p)
0
45
90
135
180
1 2 3 4 5 6 7 8 9 10 11 12
Spec.Yield 2010 Spec.Yield 2011 Spec.Yield 2012Spec.Yield 2013 Average Spec.Yield 2009
0
45
90
135
180
1 2 3 4 5 6 7 8 9 10 11 12
Average
Average yieldsSp
ecifi
c Yi
eld
(kW
h/kW
p)
0
45
90
135
180
1 2 3 4 5 6 7 8 9 10 11 12
Spec.Yield 2010 Spec.Yield 2011 Spec.Yield 2012Spec.Yield 2013 Average Spec.Yield 2009
Monthly values16 19 82 131 149 146 156 148 118 76 36 4 Average19 25 49 28 28 13 7 13 15 13 19 4 Std. Dev
119% 135% 60% 21% 19% 9% 5% 9% 13% 17% 52% 97% Std. Dev %
Ener
gy (k
Wh)
0
400
800
1200
1600
2000
2008 2009 2010 2011 2012 2013
Average Annual EnergyAnnual Energy (kWh)
1'6531'6441'878
1'4791'6031'564
Yearly values1637 kWh/kWp134 kWh/kWp8% %
Large variations on monthly basis, less variation from year-to-year comparison.
Monthly energy yields
0
100
Sum
(Max
(Ene
rgy/
Wpea
k (W
h/W
)))
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
2 3 4 5 6 7 8 9 10 11 12
Year within Month
Year 2008 2009 2010 2011 2012 2013
Energy (kWh/kWp)
Monthly irradiation
0
100000
200000
Sum
(Max
(Irra
dia
tion
(W
h/m
2))
)
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
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10
20
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13
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08
20
09
20
10
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11
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13
20
08
20
09
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10
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11
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12
20
13
20
08
20
09
20
10
20
11
20
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13
20
08
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09
20
10
20
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12
20
13
20
08
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09
20
10
20
11
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12
20
13
20
08
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09
20
10
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11
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12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
2 3 4 5 6 7 8 9 10 11 12
Year within Month
Year 2008 2009 2010 2011 2012 2013
Irradiation (kWh/m2)
Energy - Irradiation
0
100
Sum
(Max
(Ene
rgy/
Wpea
k (W
h/W
)))
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
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20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
2 3 4 5 6 7 8 9 10 11 12
0
100000
200000
Sum
(Max
(Irra
dia
tion
(W
h/m
2))
)
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
20
12
20
13
20
08
20
09
20
10
20
11
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12
20
13
20
08
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09
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20
11
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13
20
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09
20
10
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13
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08
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09
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10
20
11
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12
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13
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09
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08
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09
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10
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08
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13
20
08
20
09
20
10
20
11
20
12
20
13
2 3 4 5 6 7 8 9 10 11 12
Year within Month
Year 2008 2009 2010 2011 2012 2013
Energy (kWh/kWp)
Irradiation (kWh/m2)
Do the sun-hours and the electricity-hours correlate?
Daily energy Yield versus irradiation 2008-2013
Ener
gy (k
Wh)
0
400
800
1200
1600
2000
2008 2009 2010 2011 2012 2013
Average Annual EnergyAnnual Energy (kWh)
1'6531'6441'878
1'4791'6031'564
Specific Yield (kWh/kWp)yearly 1043 1069 986 1252 1096 827
monthly 87 89 82 104 91 69daily 2.9 2.9 2.7 3.4 3.0 2.3
Elec
trici
ty (k
Wh/
kWp/
day)
0
2
4
6
8
Irradiation (kWh/m2/day)
0 2.25 4.5 6.75 9
Linear fits of daily energy-irradiation
Elec
trici
ty (k
Wh/
kWp/
day)
0
2
4
6
8
Irradiation (kWh/m2/day)
0 2.25 4.5 6.75 9
y = 0.8194x - 0.1653
y = 0.7335x - 0.0134
y = 0.8723x - 0.0956
y = 0.8298x - 0.0591
y = 0.8949x - 0.0299
y = 0.914x + 0.1291
Irrad'08 (kWh) Irrad'09 (kWh) Irrad'10 (kWh)Irrad'11 (kWh) Irrad'12 (kWh) Irrad'13 (kWh) m d
2008 0.914 0.129
2009 0.895 -0.030
2010 0.830 -0.059
2011 0.872 -0.096
2012 0.733 -0.013
2013 0.819 -0.165
Lowest system performance in the year 2012 due to broken PV-modules.
Conclusions• Energy yields vary:
- strongly looking on a monthly basis (up to 135% for some months) - less on a year to year basis (only 8% over the past 5 years).
• A convenient figure comparing solarPV systems is the specific yield (Ya) on an annual time scale. It gives comparison of all sizes of PV-systems.
• Yields correlate well with the sun irradiation.
• Correlating irradiance with yield brings up operational problems of the PV-system.
Further reading
See us on www.gomicromorph.com !http://gomicromorph.blogspot.ch/ !twitter.com/goMicromorph !ch.linkedin.com/in/gomicromorph/ !http://www.youtube.com/user/goMicromorph !http://www.slideshare.net/PVschool !https://itunes.apple.com/ch/artist/luc-feitknecht/id513205568?l=en&mt=11
More reading
You may like also • Cloud enhancement: a few slides
on the surprising effect of clouds boosting the solarPV yieldhttp://www.slideshare.net/PVschool/clouds2-25195039 !!!
• The cost of solar electricity: the key to solar electricity is sun and cheap moneyhttp://www.slideshare.net/PVschool/cost-of-solar-electricity !
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