experience from pv system performance (including comparison of on-roof and façade systems in...
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Experience from PV system performance (including comparison of on-roof and façade
systems in Prague)
Vitezslav Benda, Zdenek MachacekCTU Prague, Faculty of Electrical Engineering
radiation temperature
datalogger
Inverter SUNRISE MINI
= 180 V+
-switchboard ~ 230 V
~ 230 Vgrid
connection=
~PV module field
++ +- - -SUNRISEdatalogger
displayunit
PC
In the year 2001, a 3kWp demonstration, on-grid connected
photovoltaic system has been built at the Czech Technical University in Prague on the roof of the Faculty of Electrical Engineering.
In the year 2001, a 3kWp demonstration, on-grid connected
photovoltaic system has been built at the Czech Technical University in Prague on the roof of the Faculty of Electrical Engineering.
PV field 1
PV field 2
PV field 3
=~
=~
=~
Temperature sensor
Radiation sensor
Display unit
Comp. networkEthernet
RJ45
Converter RS 422/RS232
RS 485
RS 232
RS 422
Power measuring
DataloggerFVS 2300E
Grid connection 230 V / 50 Hz
Shunt
Inverter SUNRISE
PC
Installed peak power: 3320 Wp
Total module area: 26 m2 Number of modules: 30 (3 fields of 10)
Latitude: 50.07 °NAltitude: 205 m
http://k313.feld.cvut.cz/solarsys/
Module type Pmax (Wp) Vpm (V) Ipm (A) VOC (V) ISC (A) cell (%) module (%)
RADIX72-112 111,5 17,4 6,41 21,5 7,04 14,9 12,8
RADIX72-108 107,8 17,1 6,29 21,5 6,98 14,4 12,4
Parameters of PV modules at radiation power 1000W/m2, spectrum AM 1,5 and temperature 25°C
PV field Tilt angle Module type Pm (Wp)
1 45° RADIX72-112 1120
2 variable RADIX72-112 1120
3 90° RADIX72-108 1080
Parameters of individual PV fields
Parameters of Sunrise inverters
Type of inverter Sunrise Mini Sunrise Micro
Input voltage 120 - 300 V 120 - 300 V
Nominal input voltage 170 V 170 V
Maximum input voltage
350 V 350 V
Output voltage 230 V,+10/-15% 230 V,+10/-15%
Output frequency 50 Hz,+/-0,2 Hz 50 Hz,+/-0,2 Hz
Output nominal current
4,4 A 3,2 A
Output nominal power 1000 W 750 W
Harmonic distortion < 3% < 5%
Maximum effectivity 93% 92%
Dark consumption 0 W 0 W
A comparison of estimated and measured energy production in period from January 2002 to December 2005
0
2000
4000
6000
8000
10000
12000
14000
Ave
rag
e d
aily
en
erg
y p
rod
uct
ion
(W
h)
Estimation Measured
2005200420032002
Energy produced by individual PV fields in period from January 2002 to December 2005
0
1000
2000
3000
4000
5000
6000
Jan
uary
Marc
h
May
Ju
ly
Sep
tem
ber
No
vem
ber
Jan
uary
Marc
h
May
Ju
ly
Sep
tem
ber
No
vem
ber
Jan
uary
Marc
h
May
Ju
ly
Sep
tem
ber
No
vem
ber
Jan
uary
Marc
h
May
Ju
ly
Sep
tem
ber
No
vem
ber
Avera
ge d
ail
y e
ne
rgy p
rod
uc
tio
n (
Wh
)
PV field 1 PV field 2 PV field 3
2002 20052003 2004
This gives the efficiency decrease of about 0.6% per 1K, which is higher than supposed decrease of cell efficiency (about 0.4% per 1K).
It means that an increase of losses with increasing temperature in other parts of system cannot be neglected.
Temperature dependence of energy conversion efficiency
9,0
10,0
11,0
12,0
13,0
14,0
15,0
Eff
icie
ncy
(%)
-5,0
0,0
5,0
10,0
15,0
20,0
25,0
30,0
35,0
PV
field
tem
pera
ture
(°C
)
Febr
uary
Mar
ch
Nov
embe
r
Oct
ober
Sep
tem
ber
Aug
ust
July
June
May
Apr
il
Efficiency
Temperature
8
9
10
11
12
13
14
0 20 40 60
PV field temperature (°C)
Effi
cien
cy (%
)
August
January
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58
Temperature distribution over the PV field areas
roof
facade
June, ambient temperature 32 °C
Tilt angle: 45°
Tilt angle: 90°
teplota (°C)
Temperature distribution over the PV field areas
December, ambient temperature -6 °C
roof
0100
200300
400500
600700
800900
8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Ou
tpu
t p
ow
er
(W)
PV field 1 PV field 2
Shadowing effect
PV field 1PV field 2
Conclusions
• Facade PV system applications can produce about 66% of electrical energy produced by the roof (45° tilted) one
• Efficiency of PV systems is strongly influenced by temperature
• PV field constructions should allow an effective cooling of PV modules