2
C. Ballif
• PV electricity is manageable: it can be dispatched and used on demand, thanks to
the possibility of storage, e.g. in batteries or via pumped hydroelectric systems.
• With further decreasing costs, it will become convenient and cost-effective to
transform solar electricity into chemical fuels (power-to-gas), enabling versatile
long-term storage.
Hence, photovoltaics not only has the potential to become, in the foreseeable
future, the World’s major source of electricity—it could also become, by the second
half of the century, the major source of energy, in general, via the transformation and
storage of electricity.
This book is primarily concerned with the core component of a photovoltaic (PV)
system—with solar cells and modules; it will describe the different types of solar cells
and their assembly into entire modules, as well as various aspects of their application.
1.1.1 Is There Enough Energy from the Sun?
When the sun shines, it typically brings a power of 1000 W per m
2 on the ground.
Thus, an area covered by a PV module with an efficiency of 20% (a typical value
for a high-quality module today) will provide a peak power of approximately 200 W
(referred to as Watt Peak or W p ). Depending on the location, every year the sun brings
on each square metre of the ground 800–2700 kWh, as illustrated in Fig. 1.1. A welloriented module at 40° latitude (Rome, New York, Beijing) receives around 1500–
1600 kWh/m
2 every year, i.e. the energy equivalent of one barrel of oil (159 litres).
Fig. 1.1 Daily and yearly total global horizontal irradiation (GHI) values—given per m 2 and
representing the energy received by a flat, horizontal surface. (Map obtained from the “Global Solar
Atlas 2.0, a free, web-based application developed and operated by the company Solargis s.r.o. on
behalf of the World Bank Group, utilizing Solargis data, with funding provided by the Energy Sector
Management Assistance Program (ESMAP). For additional information: https://globalsolaratlas.
info)
C. Ballif
• PV electricity is manageable: it can be dispatched and used on demand, thanks to
the possibility of storage, e.g. in batteries or via pumped hydroelectric systems.
• With further decreasing costs, it will become convenient and cost-effective to
transform solar electricity into chemical fuels (power-to-gas), enabling versatile
long-term storage.
Hence, photovoltaics not only has the potential to become, in the foreseeable
future, the World’s major source of electricity—it could also become, by the second
half of the century, the major source of energy, in general, via the transformation and
storage of electricity.
This book is primarily concerned with the core component of a photovoltaic (PV)
system—with solar cells and modules; it will describe the different types of solar cells
and their assembly into entire modules, as well as various aspects of their application.
1.1.1 Is There Enough Energy from the Sun?
When the sun shines, it typically brings a power of 1000 W per m
2 on the ground.
Thus, an area covered by a PV module with an efficiency of 20% (a typical value
for a high-quality module today) will provide a peak power of approximately 200 W
(referred to as Watt Peak or W p ). Depending on the location, every year the sun brings
on each square metre of the ground 800–2700 kWh, as illustrated in Fig. 1.1. A welloriented module at 40° latitude (Rome, New York, Beijing) receives around 1500–
1600 kWh/m
2 every year, i.e. the energy equivalent of one barrel of oil (159 litres).
Fig. 1.1 Daily and yearly total global horizontal irradiation (GHI) values—given per m 2 and
representing the energy received by a flat, horizontal surface. (Map obtained from the “Global Solar
Atlas 2.0, a free, web-based application developed and operated by the company Solargis s.r.o. on
behalf of the World Bank Group, utilizing Solargis data, with funding provided by the Energy Sector
Management Assistance Program (ESMAP). For additional information: https://globalsolaratlas.
info)