2. The sun
2
Passive heat
This is heat which we receive from the sun naturally; this can be
taken into account in the design of buildings so that less
additional heating is required
Solar thermal
Uses the sun’s heat to provide hot water for buildings
Photovoltaic (PV) energy
Converts energy from the sun into electricity
6. Some figures
6
PV annual increase
Source: IEA Trends in Photovoltaic Applications
7. Europe: Global PV market leader
7
Source: Global Market Outlook for PV until 2013
8. How does PV work
8
Photovoltaic effect
Phenomenon that certain materials produce electric current
when they are exposed to light
Discovered in 1839 by 19 year old Alexandre Edmond
Becquerel French physicist
1873: Willoughby Smith discovered the photoconductivity of
selenium
1923: Albert Einstein received the Nobel Prize for his
theories explaining the photoelectric effect
1954: The PV effect in Cadmium was reported; primary
work was performed by Rappaport, Loferski and Jenny
9. How does PV work
9
PN Junction and Semiconductors
One pure silicon crystal is doped with two
different dopants (e.g. arsenic, gallium,
aluminum, phosphorus)
One half of the crystal is left electron
deficient: p-type layer and the other half has
an excess of electrons: n-type layer
There is an electric field across the junction
between the two halves
Electrons in the crystal can only travel in one
direction - from the electron rich half to the
electron poor half
Where the two halves of the crystal meet is
called a PN junction, and this doped crystal
is a semiconductor
10. How does PV work
10
Energy from sunlight
The light from the sun is made up of
packets of energy called Photons
When a visible light photon strikes a
solar cell it can pass straight through, be
reflected, or be absorbed
If the photon is absorbed its energy is
absorbed by an electron enabling it to
cross the junction and fill a hole
Electrons are physically moving across
the PN junction and the holes are
moving in the opposite direction
DC current is established around the
load circuit
11. PV power
11
The power that a PV produces depends on
The amount of incident sunlight (irradiance)
The efficiency of the PV at converting this light to
electricity
Peak power (Wp)
Output power at Standard Test Conditions (STC)
STC: teta=25ºC; G=1000W/m2
14. Average monthly irradiation
14
400
307,0
300,2
300
Radiação solar incidente G (W/m2)
273,9
262,9
217,2
209,6
200
177,2
135,5
111,9
100 87,8
77,0
63,6
0
Jan Fev Mar Abr Mai Jun Jul Ago Set Out Nov Dez
17. PV technologies
17
Crystalline silicon technology
Efficiency ranges between 12% and 17%
This is the most common technology representing
about 90% of the market today
Types of crystalline cells
Monocrystalline (Mono c-Si)
Polycrystalline (or Multicrystalline) (multi c-Si)
Ribbon sheets (ribbon-sheet c-Si)
18. PV technologies
18
Thin film technology
Depositing extremely thin layers of photosensitive materials
onto a low-cost backing such as glass, stainless steel or
plastic
Lower production costs compared to the more material-
intensive crystalline technology
Price advantage is currently counterbalanced by lower
efficiency (5% to 13%)
Types of thin film modules depend on the active material
Amorphous silicon (a-Si)
Cadmium telluride (CdTe)
Copper Indium/gallium Diselenide/disulphide (CIS, CIGS)
Multi junction cells (a-Si/m-Si)
20. PV technologies
20
Other cell types
Concentrated photovoltaic (CPV)
Designed to operate with concentrated sunlight
Built into concentrating collectors that use a lens to focus the
sunlight onto the cells
Use very little of the expensive semiconducting PV material
while collecting as much sunlight as possible
Efficiencies are in the range of 20 to 30%
Flexible cells
Based on a similar production process to thin film cells, when
the active material is deposited in a thin plastic, the cell can be
flexible
This opens the range of applications, especially for Building
integration (roofs-tiles)
21. 21 CPV
MST Ltd. (Israel) is developing a novel concentrating PV (CPV) technology.
The basic unit is the solar tracker, with an output power of about 50 kWp.
The system's lenses concentrate sunlight to 500 suns on multi-junction highly-efficient (37 %) solar
cells.
23. PV applications
23
Grid-connected domestic systems
Most popular type for
homes and businesses
in developed areas
Connection to the local
electricity network
An inverter is used to
convert the DC power
to AC
28. PV applications
28
Grid-Connected power plants
Production of a large
quantity of
photovoltaic electricity
in a single point
The size ranges from
several hundred
kilowatts to several
megawatts
31. PV applications
31
Off-grid for rural electrification
Where no mains
electricity is available
The system is
connected to a battery
via a charge controller
An inverter can be
used to provide AC
power
Use of normal
electrical appliances
32. PV applications
32
Off-grid industrial applications
Repeater stations for
mobile telephones
Traffic signals
Marine navigation aids
Security phones
Remote lighting
Highway signs
Waste water treatment
plants
34. Moura PV Power Plant
34
One of the world largest centralized PV plants, with
45,6 MWp installed power
Located @ Amareleja, east Alentejo and owned and
operated by Acciona Energy
Built in about 13 months
262 080 PV modules
2520 solar trackers (azimuthal)
Area occupied 250 ha
The estimated annual output is 93 GWh
Final yield slightly over 2000 kWh/kWp
Source: IEA Report 2008 - Portugal
37. 37 Double sun (Portugal)
WS Energia developed and patented the DoubleSun® Technology which duplicates the annual
energy yield of commercial PV modules by combining extremely light flat mirrors with easy-to-
mount, quick-to-install tracking systems.
38. Costs
38
Feed-in tariff vs market prices
Renewables feed-in tariff
Market price
Source: Energy Services Regulatory Authority
