Technical Application Papers No.10 Photovoltaic plants - ABB

Index
Technical Application Papers
Photovoltaic plants
Introduction ............................................... 4
PART I
1 Generalities on photovoltaic
(PV) plants ............................................ 5
1.1 Operating principle ................................... 5
1.2 Energy from the Sun ................................. 5
1.3 Main components of a photovoltaic plant ... 8
1.3.1 Photovoltaic generator ................................... 8
1.3.2 Inverter..........................................................11
1.4 Typologies of photovoltaic panels ......... 12
1.4.1 Crystal silicon panels ....................................12
1.4.2 Thin film panels ............................................13
1.5 Typologies of photovoltaic plants........... 15
1.5.1 Stand-alone plants .......................................15
1.5.2 Grid-connected plants ..................................16
1.6 Intermittence of generation and storage of
the produced power ............................... 17
2 Energy production ..................... 18
2.1 Circuit equivalent to the cell ................... 18
2.2 Voltage-current characteristic of the cell ... 18
2.3 Grid connection scheme ........................ 19
2.4 Nominal peak power .............................. 20
2.5 Expected energy production per year .... 20
2.6 Inclination and orientation
of the panels ........................................... 22
2.7 Voltages and currents in a PV plant ....... 24
2.8 Variation in the produced energy ........... 24
2.8.1 Irradiance ......................................................24
2.8.2 Temperatures of the modules .......................25
2.8.3 Shading ........................................................25
3 Installation methods and
configurations ................................ 26
3.1 Architectural integration ................................. 26
3.2 Solar field layout ............................................ 27
3.2.1 Single-inverter plant ...............................................27
3.2.2 Plant with one inverter for each string ....................27
3.2.3 Multi-inverter plant .................................................27
3.3 Inverter selection and interfacing ................... 28
3.4 Choice of cables ............................................ 32
3.4.1 Types of cables .......................................................32
3.4.2 Cross sectional area and current carrying capacity..... 32
PART II – Italian context
4 Connection to the grid and
measure of the energy ........... 33
4.1 General ........................................................... 33
4.2 In parallel with the LV network ....................... 34
4.3 In parallel with the MV network ..................... 36
4.4 Measurement of the energy produced and exchanged
with the grid .................................... 38
5 Earthing and protection
against indirect contact ...... 39
5.1 Earthing .......................................................... 39
5.2 Plants with transformer .................................. 39
5.2.1 Exposed conductive parts on the load side of the
transformer .............................................................39
5.2.1.1 Plant with IT system ..................................39
5.2.1.2 Plant with TN system .................................39
5.2.2 Exposed conductive parts on the supply side of
the transformer .......................................................40
Follows
1