AIA_PV_GLASS_EN (1)

t
ONYX SOLAR
40107985
PHOTOVOLTAIC (PV) GLASS
GLAZING
PHOTOVOLTAIC (PV) GLASS
PVGLAZING 101
Diego Cuevas
01/01/16

COURSE REGISTERED WITH AIA CES
Credit(s) earned on completion of this
course will be reported to AIA CES for
AIA members.
Certificates of Completion for both AIA
members and non-AIA members are
available upon request.
This course is registered with AIA CES for
continuing professional education. As such, it
does not include content that may be
deemed or construed to be an approved or
endorsed by the AIA for any construction
material or building, handling, utility, distributing
method.
__________________________________________
Questions related to specific materials, methods, and
services will be addressed at the conclusion of this
presentation.

This presentation is protected by US and International Copyright
laws. Reproduction, distribution, display and use of the
presentation without written permission of the speaker is
prohibited.
© Onyx Solar Energy, S.L. 2015
Copyright Materials

Course
Description
Photovoltaic (PV) glass and its Building Integrated Photovoltaic Applications (BIPV) offer
buildings the opportunity of generating onsite free clean electricity from the sun. The BIPV
provides an easy solution to designing a PV façade, skylight and canopy. However a
basic set of skills and product knowledge is needed to improve the outcome of the
installation.
This course covers the main photovoltaic glass technologies available in the market,
discussing their advantages and disadvantages, compositions, architectural specs, and
the design-performance relationship.
The course will also explore the main PV applications: curtain walls, ventilated façades,
skylights, louvers, canopies, and slip-resistant floors. Emphasis will be on understanding its
interaction with the structural/framing system as well as on the Electrical Balance of System
(electrical equipment) required to make it work. And how much does the PV Glass cost?
The course will cover that answer too.

Learning
Objectives
At the end of the this course, the participants will be able to:
1.- Recognize the main photovoltaic technologies commercially available in the market
for their incorporation into the building´s skin by going over the content and graphics of
the course.
2.- Acquire knowledge to evaluate which photovoltaic glass will be a better fit for a
project by understanding its characteristics, advantages and disadvantages.
3.- Acquire an improved set of skills to design building envelopes with PV glass, learning
from the examples with the drawings provided throughout the course.
4.- Understand the value proposition of the PV glass, and measure it by learning from cost
information and real project case studies.

INDEX
1.- What is a Photovoltaic (PV) Glass?
1.1.- Key Concepts
2.- What is the PV Glass made of?
2.1.- Glass lites
2.2.- Solar cells
2.3.- Encapsulants
2.4.- Junction Box
2.5.- Additional Components
3.- Amorphous Silicon Photovoltaic Glass
3.1.- Physical characteristics
3.2.- Sizes, shapes, thicknesses
3.3.- Transparency
3.4.- Performance
3.5.- Applications
3.6.- Special Application: PV Floor Tile
4.- Crystalline Silicon Photovoltaic Glass
4.2.- Sizes, thicknesses and shapes
4.3.- Transparency
4.4.- Performance
4.5.- Applications
5.- Structural/Framing systems

6.- Electrical Balance of System: main components
6.1.-Energy Management Alternatives
A. Direct consumption with battery
B. Direct consumption
C. Connecting to the grid system
7.- LEED Certification/Green Building Elements
8.- PV Glass Specs: 088000/ 263100/ Special Function
Glazing Specs
9.- Cost information and ROI
9.1.- Cost Information
9.2.-ROI
10.- Designing your envelope with PV Glass: general
recommendations
11.- Tools
11.1.-Photovoltaic Estimation Tool
11.2.-Energy Modeling Tool
11.3.- Glazing Thermal Transmitance
Case Study: Photovoltaic Ventilated Façade
INDEX

1.- WHAT IS A PHOTOVOLTAIC GLASS?
Photovoltaic(PV) glass is an architectonic glass which besides providing the building with
the same properties as a conventional glazing, it also generates free electricity from the
sun. It is therefore, the only building material available in the market that provides your
building a return on the investment.

1.1.- Key concepts
• PV Glass substitutes conventional glass within the building envelope.
• PV Glass offers the same mechanical behavior as a conventional glass that has the same
build-up.
• PV Glass is always a laminated glass product.
• PV Glass generates free electricity from the Sun.
• Basic idea: think of PV Glass as a traditional, architectonic glazing, which also provides you free
electricity from the Sun.

2.- WHAT IS THE PV GLASS MADE OF?
2.1.- Glass lites
2.2.- Solar cells
2.3.- Interlayers
2.4.- Junction box
2.5.- Optional configuration elements

2.1.- Glass lites
There are no special requirements for the glass lites that compose a photovoltaic glass unit.
In fact, glass lites for PV glazing units can present the same thermal treatments,
characteristics and properties as the traditional glazing composition.
COMMON HEAT TREATMENTS:
- Heat Strengthened Glass: two times stronger than annealed glass of the
same thickness and size. If broken, this type of glass reduces the chance of
vacating the opening since it breaks in large shards similar to annealed glass.
- Fully Tempered Glass: two times stronger than Heat Strengthened Glass of
the same thickness and size. If broken, it will shatter into fine pieces, reducing
the chances of injury. It will likely vacate the opening.
- Heat Soaking Glass: due to nickel sulfide inclusions, the glass material can be
fragile when there is a sudden change in the temperature. The heat-soak
process is carried out to help rigidify the glass in such scenario, which also
makes it stronger than the tempered glass.

2.1.- Glass lites
COATINGS:
- *Low-emissivity coatings: low-e coatings can be applied on the glass for a
greater thermal performance whenever required. Pyrolytic/hard coatings are
usually applied. * See next slides to get more information.
- Reflective coatings: these can also be applied to the photovoltaic glass
whenever required, however the coating must be placed always in a surface
behind the solar cells, to not hinder the efficiency of the photovoltaic glass
unit.
- Hydrophobic coatings: can also be applied on to the glass, but will
drastically lower the power output since they reduce the amount of sunlight
reaching the photovoltaic cells.

2.1.- Glass lites
FRITS, SILKSCREENING:
-Frit patterns, silkscreen designs are also available and compatible with the glass used for PV Glazing applications.
The only rule is to place it behind the solar cells to not obstruct the sunlight for the photovoltaic cells.

2.1.- Glass lites
ACID ETCHING:
Photovolatic glass can incorporate acid etch treatments too; if required on
the outer surface of the photovoltaic glass, it is important to select a good
treatment to keep the performance of the photovoltaic glass as unaffected
as possible. Acid etching over the solar cells could decrease the efficiency of
the system by only 2% if they are well selected and counting on the
amorphous Silicon technology. If the acid etch treatment goes on any
surface # that is behind the solar cell, there will not be any decrease in the
power output of the system.

* COATINGS - SPECIAL MENTION. Low Emissivity Glass:
A High Performance PV Glass
Low emissivity (Low-e) coating could be applied onto the PV glass in order to prevent the
heat loss. This energy efficient invisible coating significantly reduces heat transfer and
helps maintaining heat in the interior space during the cold winter times. It is an effective
way of reducing carbon footprint by lowering the monthly energy bill.
How Low-e coating works:
The low-e coating manages two different wavelengths from the sun: short wave and
long wave. Taking into account that heat always flows towards the cold, the low-e
coating allows the glass to maintain the heat on the interior side against the cold exterior.
The majority of the solar radiations that will reach the windows are the short waves; the
coating allows these short waves to pass through into the interior. These short waves
warm up the indoor items such as furniture and carpets, which then the energy is
converted to the long wave radiations. Consequently, these long waves will reflect back
into the interior space thus retaining the heat.

Carefully considering the role of solar
properties is essential in accomplishing
thermal comfort indoors. To gauge the
impact of the solar properties on the
indoor temperature, SHGC (Solar Heat
Gain Coefficient) and g-value are used.
The Thin Film technology, which refers to
a class of PV material that is applicable
to the composition of glass, limits the g-
value to the range of 10-40%.
In other words, an optimal amount of
the natural light will illuminate the
interior space without the harmful solar
radiations such as the UV and the IR.
Exterior
Interior
Implication of Low-e on PV glass

Conventional Glass: Harmful radiation and solar heat
gain coefficient passes through the glass for less
favorable indoor condition.
PERFORMANCE COMPARISON; Solar Radiation Filtration: Conventional glass vs. PV glass
Thin Film (PV) Glass: Harmful radiation and solar heat
gain coefficient are significantly reduced, effectively
enhancing the indoor comfort level. (99% UV and 85-
95% IR radiations).

2.2.- Solar cells
Solar technology keeps evolving everyday, aiming to improve efficiencies, lifespan, and
even the aesthetics of the technology. The following table shows several of the major solar
technologies available in the market, however this course will focus on the most robust
ones for photovoltaic glass applications: amorphous silicon and crystalline silicon solar
cells. This course will be reviewing both technologies deeper.
TYPE OF PV SOLAR CELL PRIMARY MATERIALS EFICIENCY (%)
Thin Film
CIGS
Compound of Copper
Indium Gallium Selenium
7% - 12%
CdTe
Compound of Cadmium
and Telluride
8% - 11%
A-Si
Silicon
6% - 10%
Crystalline Silicon
Monocrystalline 16% - 20%
Polycrystalline 13% - 16%
III-V multijunction
PV
Tandem Cells
Indium Gallium
Phosphide
Indium Gallium Arsenide
27% - 30%
Excitonics and
quantum-structured
photovoltaics
OPV Polymer 3%
DSSC Titanium Dioxide 6% - 8%

2.2.- Solar cells
EFFICIENCY:
Is related to the amount of energy from the 1000 W/m² under STC that the technology
can convert to energy (kWh).
For normal use, the monocrystalline cells are the most efficient, followed by polycrystalline.
While the best monocrystalline panels measure slightly over 20%, most of the panels in
production today measures at about 15% of the available light energy. Amorphous
panels and other thin layers rarely exceed 10% efficiency.
In other words monocrystalline cells can transform slightly over 200 W/h (under the STC of
1000 W/m²).
•NOMINAL PEAK POWER (kWp) VS. GENERATED POWER (kWh/year):
An installed PV glass unit brings its own nominal peak power that is also referred to as
installed power. It is fundamental to distinguish between the two concepts that are often
confused: installed power (kWp) and energy generated (kWh).
The kWp relates to the integration surface, the applied technology, transparency degree,
etc. The generated energy, expressed as kWh/year, on the other hand, will depend on
the local radiation conditions that affect the building and the tilt and orientation of the
photovoltaic glass. Because there will be less photovoltaic material with more etching,
the performance of the PV glass decreases as the transparency increases.

2.3.- Interlayers
Polyvinyl Butyral (PVB): it is maybe the most
common interlayer used within the glass industry for
laminated products. It is normally available in three
different thicknesses:
0.03”
0.06”
0.09”
and typically used with amorphous Silicon
photovoltaic glass products.
SentryGlass® by DuPont: it is an ionoplast
interlayer which minimizes deflection; it is stronger
and more rigid than traditional interlayers, so it
performs well for glass applications frequently used
to withstand storms, blasts and bigger impacts. It is
also available in different thicknesses:
0.06”
0.09”
0.10”
Vanceva ® Color by Solutia: an interlayer made of
base colors that can be combined in up to four
layers together, to achieve the desired color for the
photovoltaic glass. The interlayer is normally placed
behind the solar cells in triple laminated glazing
units, so that the power output of the glass does not
decrease. Typical thickness is 0.015” and normally
up to four layers stick together to reach 0.06”
overall thickness.
EVA: typically specified with crystalline Silicon
technology, since it provides better electrical
isolation compared to PVB. It is weather resistant
and has a high light transmission, which offers
crystalline Silicon photovoltaic glass a reliable
lamination result and improved electrical isolation.
Typically available in thicknesses as follows, and
offering the possibility of using more than one layer
together for greater thickness.
0.015”
0.030”

2.3.- Interlayers
UV and chemical curable resins: liquid
resin that is injected in between the
layers of glass which is going to be
laminated.
UV curable resin cures with its exposure to
low-intensity UV light; chemical curable
resin cures with thermal energy. Resins
are sometimes used as an alternative
material that meets more stringent codes
in terms of glass strength and safety, such
as in hurricane prone areas.

2.4.- Junction Box
The Junction Box is the component of the photovoltaic module necessary for its electrical
connection.
Electrical junction boxes are attached to the PV glass unit, either at the edge of the
laminated glass, or in the rear lite of the composition. Within these two possible options,
there is certain flexibility to place it in the most suitable location within the rear glass or
within the edge.
Each module is supplied with its own junction box. The junction box can be bipolar or
monopolar. The bipolar one has positive and negative polarities and is the most commonly
used for modules. The monopolar junction box, on the other hand, only has a single active
pole (positive or negative), and two units per module must therefore be placed.

2.4.- Junction Box
The selection of the box type will be determined by the nature of assembly required for the
project. If you consult our technical guide, you will see that the technical specifications of
each standard unit come with a diagram of each particular module, where its
appearance can be seen in terms of its size and the placement of the junction box. The
diagram shown has a monopolar box and this is why we can see two components.

2.5.- Other additional components
By other components we refer to other configurations for the photovoltaic glass that,
depending on the performance desired for the project, may be required.
A typical additional component is a spacer to improve the U-value of the photovoltaic
glass unit; counting on an double glazing unit and considering the coatings applied, the
photovoltaic glass can reach as low U-values as 0.13 BTU/h*Ft2*Fº.
Regarding the spacer, frequent thicknesses for the spacer are ¼”, ½” and 10/16”,
depending on the insulation required. Air and Argon fills are commonly requested.
.
Picture on the left
shows a typical
amorphous Silicon
double glazing
configuration, as a
reference.

3.- AMORPHOUS SILICON
Amorphous silicon technologies (a-Si) are formed by
depositing various types of treated silicon onto the
surface layer of the glass, followed by laser etching to
establish the edges of the cells and to create
transparency when necessary. As mentioned before,
the efficiency of this photovoltaic glass ranges between
6% and 10%. Photovoltaic efficiency is defined by the
percentage of power converted into power from the
total amount of sunlight properties absorbed by a PV
glass unit.
Within constructive solutions on curtain walls and
skylights, where transparency and homogeneity (if
desired by client) take precedence, amorphous silicon
technology is commonly chosen.

3.- AMORPHOUS SILICON
Advantages of the amorphous silicon technology:
• Greater energy production (kWh) at the same installed power
(kWp).
• Low temperature coefficient. The yield of amorphous silicon
photovoltaic glass under high temperature conditions is better
than in crystalline modules.
• Greater capability of producing more energy under indirect/
diffused sunlight & overcast climate(e.g. indirect sun irradiation,
overcast climate, early morning and late at night, less
favorable orientation, etc.).
• Better behavior in the presence of shadows.
• Less reliant on the angular positioning of the installed glass.
• Enables a more aesthetic integration to the architecture of the
building.
• Shorter amortization period.
• Sunscreen effect and daylight facilitator, better transparency.

The appearance of the amorphous
silicon glass is different from the
exterior and the interior side of the
PV glass. Viewed from a distance
the exterior side is similar to the
tinted glass, whereas from the
interior, the views outside are clear
and unobstructed. Between the
exterior and the interior, whichever
side is brighter will be more visible
from the opposite.
Let’s take an office building with an
amorphous silicon curtain wall for
example: you will have a clearer
view of the outside from the office
during the daytime, whereas during
the night time, the opposite is true
when the office spaces are
illuminated with the lighting.
PV Skylight. 20% Semitransparent. View from the exterior.
PV Skylight. 20% Semitransparent. View from the interior.

3.2.- Sizes, Shape and Thickness

3.2.- Sizes
Photovoltaic glass can be normally manufactured in a variety of sizes. For the amorphous
silicon technology, market sizes usually range from 1245mm x 300mm (49’’ x 12’’) up to
3000x1500 mm (10’ x 5’).
Notwithstanding, amorphous silicon PV glass can be customized in size and thickness.
Within this range, the PV glass can also be adapted to an existing design. However, using
standard sizes may bring additional cost benefits.
The figure below lists some of these standard sizes for the a-Si PV glass.

3.2.- Shape & Colors
Although the amorphous silicon PV Glass
normally comes in rectangular shapes,
irregular shapes such as trapezoid could
also be manufactured. The irregular
shapes are not recommended for the
amorphous Silicon.
A wide range of colors –up to 1,500- is
available on the market for a-Si
photovoltaic glass. The colored PVB
interlayer is incorporated during the
lamination process.

3.2.- Thickness
The thickness of the PV unit would vary depending on the composition of the glass
(double pane laminated, or triple pane laminated) and whether it is with or without an air
space (i.e. single or double glazing).
As any other architectural glass, thermal and acoustic insulations requirements could be
satisfied by means of Air or Argon chambers, besides additional high performance
coatings. When the unit includes an air chamber, it is pre-assembled at the manufacture
facility prior to shipping.
A single glazed PV unit
can be laminated
glass or triple pane
laminated glass.
A single glazed PV unit
typically consists of
two layers of fully
tempered / HS glass
laminated with a PV
glass layer in
between.

3.2.- Thickness
As shown in the figure above, the PVB (Polyvinyl Butyral) foil is used in order to join all the
layers together.
This is an example of a laminated composition whose thickness results to 7.16 mm (9/32’’).
The thickness of the unit varies depending on the choice of the glass composition. The
inner layer of glass tempered and float glass can be provided for the thickness of 4, 5, and
6 nominal millimeters. (5/32’’, 3/16’’ and ¼’’ respectively).

3.2.- Thickness
The triple laminated PV glass pane has a configuration that can be composed of different
glass thicknesses: 4, 5, and 6 nominal millimeters (fully tempered/heat strengthened/heat
soak tested). The central layer, which is the PV interlayer, will always be 3.2 mm float glass.
The weight of the glass will depend on its configuration. For example, a 3mm +3mm (1/8’’
+ 1/8’’) safety glass would weigh 16.7 kg/Sqm; whereas a triple pane laminated 6 mm+3
mm+ 6mm (1/4’’+1/8’’+1/4’’) safety glass would weigh 41,0 kg/sqm.
Therefore, the
weight of any
photovoltaic
glazing is
calculated as any
other regular
glazing material.

3.3.- Transparency
During the manufacturing process, transparency is achieved by removing some portion of
the amorphous silicon layers via the laser etching.
Since the etching removes the photovoltaic material, the output power of the glass is
inversely proportional to the transparency degree. The higher the transparency degree,
the lower the output power with more transmitted daylight. Normally 10 and 20% semi-
transparency degrees offer a perfect balance between light transmission and energy
yield. To make the best discernment between the trade-off, it is recommended to count
on the professional advice.

3.4.- Performance
The performance of a photovoltaic glass will depend on the following elements:
- Efficiency of the technology (refer to slide #10, solar cells)
- Geographical parameters (i.e. latitude, longitude, altitude)
- Azimuth (is the compass direction from which the sunlight is coming)
- Maintenance
Measurement conditions (Standard Testing Condition)
To evaluate the efficiency of a PV glass, the electrical characteristics must be tested under the following
standard condition:
- 1000 W/m²
- AM 1.5 global (air mass coefficient defines the direct optical path length through the Earth's
atmosphere)
- 25°C
Output values to measure:
- Short circuit current (Isc)
- Open circuit voltage (Voc)
- Maximum output (Pmpp)
- Current at Pmpp (Impp)
- Voltage at Pmpp (Vmpp)
- Fill factor (FF)
- Efficiency (useful power output/total power output)

3.4.- Performance
Amorphous Silicon technology performs very well under both direct sunlight and diffuse
light conditions. Despite it shows a lower power output per Sqm compared to crystalline
Silicon technology, it performs very well under certain climatic conditions and non
optimized orientations and tilts. For example, amorphous Silicon performs well for vertical
applications such as curtain walls, ventilated facades and other cladding systems;
considering the fact that a vertical application is not naturally oriented or tilted to
maximize solar energy harvest, this technology makes the most under these conditions
where diffuse light plays a key role.

3.5.- Applications
Due to its semi-transparency property, the Amorphous Silicon is often used where the
transparency takes precedence and/or the integration takes place where there is a
limited direct sunlight irradiation.
Moreover, the tinted glass appearance of the PV glass allows an easier architectural
integration with the design of the building than it is with the crystalline silicon (explained
on the following pages).
Its application includes any form of façade system (ventilated, curtain wall, cladding,
etc.), as well as skylights, canopies, glass railing, flooring, parking lot, louvers, and urban
furniture.

An example of PV Curtain Wall and PV Skylight from a project in Spain. Both of the components feature 20% transparency degree
PV glass with the combination of non-PV Glass, providing more homogeneous appearance.
AMORPHOUS SILICON PV SKYLIGHT AND CURTAIN WALL

Retrofit of an historic market in Madrid, Spain. The a-Si photovoltaic Skylight with 20% transparency provides the market underneath
natural illumination as well as to filter most of the UV and IR radiations, while simultaneously generating electricity from the Sun.
AMORPHOUS SILICON PV SKYLIGHT

Photovoltaic Skylight Retrofit in Spain. Three different levels of transparency (10%, 20% and 30%) combined with different colors in
order to achieve a Pierre Mondrian aesthetic.
AMORPHOUS SILICON PV SKYLIGHT

Photovoltaic Skylight and Curtain Wall. University Building in Spain. 20% transparency IGU was chosen for both systems to assure
natural sunlight illumination for the interior space, as well as the thermal and acoustic insulation.
AMORPHOUS SILICON PV SKYLIGHT AND CURTAIN WALL

PV Parking Lot, Italy. Dark a-Si modules selected for the solution with a high level efficiency.
AMORPHOUS SILICON PV PARKING LOT

Curtain Wall System for a new construction in Spain. The transparency degree is at 10% and was chosen by the client to guarantee
a tinted glass effect from the exterior while maintaining views outwards from the interior.
AMORPHOUS SILICON PV CURTAIN WALL

Photovoltaic Ventilated façade made of opaque amorphous Silicon PV Glass held by clips onto the framing system.
AMORPHOUS SILICON PV VENTILATED FAÇADE

Retrofit of the HQ’s of a Mexican company in Monterrey with a PV Ventilated Façade. The integration was carried out with 20%
semitransparent glass with black colored PVB for aesthetic purposes.

PV Ventilated Façade of Opaque PV glass in combination with Corian. Solar Decathlon Competition 2010.

Photovoltaic Ventilated Façade for Pzifer Building in Spain. Combination of different degrees of semitransparency together with
white glass.

3.5.1- Special Application: Amorphous
Silicon PV Floor Pavers
This type of integration has been developed as
a raised flooring system. In this sense, like the
rest of photovoltaic solutions we have seen so
far, these pavers have been developed to be
installed just as any other exterior technical
floor.
The photovoltaic paver consists of triple pane,
laminated glass. The outer layer features an
acid etching treatment to give it a slip-resistant
finish.
PV Pavers comes in several sizes; a common
size is 600 mm x 600 mm (24” x 24”) since it is a
standard size for the conventional raised
flooring systems such as ceramic or stone
pavers.
Counting on standard sizes, any deck flooring,
terrace and sidewalk can easily incorporate the
PV tile.

3.5.1- Special Application: Amorphous
Silicon PV Floor Pavers
The PV flooring system can be designed
such that it works as a beacon element or
outdoor lighting, operating autonomously
with self sustaining LED system.
The system consists of a number of
semitransparent photovoltaic tiles units that
are retro-lighted from the pit by a LEDs
system.
A battery (connected to the PV source) is
incorporated to the system to feed the LEDs
according to the needs of the facility.
Other electrical device manages the
energy produced by the photovoltaic tiles
feeding the battery during the day and
giving energy to the LEDs (from the battery)
in low light level periods.

3.5.1- Special Application:
Amorphous Silicon PV Floor Pavers
1.- PV floor pavers do not take up any extra
space on the rooftop, deck, or any other
given area. They can be walked on and
can withstand the weight of the people
standing on them.
2.- PV floor pavers generate electricity from
the diffused sunlight; they can still generate
electricity when the tiles are under shades.
3.- Great P.R. benefits; PV floor tiles are one
of the most innovative ways to incorporate
technology. They have been patented by
the PV Glass manufacturer Onyx Solar, and
they offer the users the possibility to walk on
the sunshine.
PV Floor is also available in customized sizes, up to 10’ x 5’.
Colors are also an option whenever a fancy finish might be of interest.

4.- CRYSTALLINE SILICON PHOTOVOLTAIC GLASS
4.3.- Transparency
4.4.- Performance
4.5.- Applications

Crystalline Silicon (c-Si) is probably the most renown solar technology because it is
normally used to manufacture traditional PV panels for roof-mounted applications and
solar farms. However, it is also a very useful technology for building integrated
photovoltaic applications.
Within crystalline technology, there are monocrystalline silicon cells (formed from a single
silicon crystal) and polycrystalline cells (formed by different macrocrystals that are formed
from different crystalline seeds in vertical growth ovens). These cells can, in turn, be of
different sizes: 5’’ or 6’’, typically.
Crystalline glass usually has power values of around 100 – 180 Wp per square meter,
depending on the technology, the separation between cells and the efficiency of the
cells.
In constructive solutions where electricity generation takes precedence over
transparency, such as pergolas, brise soleils or canopies, it is usual to choose crystalline
silicon technology.

The advantages of crystalline silicon technology
over amorphous:
• Greater nominal power per square meter
(Wp/m²).
• Less installation surface area to equal power.
• Greater efficiency (between 15% – 18%).
Photovoltaic efficiency is defined as the
percentage of power converted into electricity
from the total sunlight absorbed by a module.
• Produces greater power under direct sunlight.
• Better transparency

To generate maximum power output under the direct sunlight while providing shade, the
crystalline silicon is often utilized. Though its applicability is not limited, the crystalline is more
often manifested in canopies, skylights, parking lots, and spandrel glass. The picture below
illustrates its use as a canopy system at the Bay Area Rapid Transit Station in Union City, CA,
where the transparency is not need but still benefits from the natural sunlight that is filtered
through

The crystalline silicon technology
includes two subcategories; Mono
and Poly crystalline. Mono-
crystalline is slightly more efficient
than poly-crystalline (the internal
structure is composed by aligned
crystals). The Poly-crystalline
technology is based on the same
technology but in its internal
structure the crystals are
misaligned, this means less
efficiency, and its appearance
consists of varying shades of blue.
Mono-crystalline Silicon, glass on glass
Poly-crystalline Silicon, glass on glass

4.2.- Sizes
A glass on glass crystalline silicon unit can be manufactured in variety of sizes, thicknesses
and shapes. Its typical maximum size is of approximately 2100 mm x 2100 mm (83” x 122”).
Both the typical industrial standard sizes (shown below) and the customized sizes are
available to suit each project’s needs. For sizes larger than 2100 mm x 2100 mm, please
consult with a PV Glass manufacturer.

4.2.- Thicknesses
Regarding to thicknesses, glass on glass crystalline units consist of the solar cells embedded
in between two layers of glass, which is laminated with different interlayers as required. The
typical individual glass pane thicknesses are 4, 5, 6, 8 and 10 mm each. (5/32”, 3/16”, ¼”
and 5/16”). Besides these, there is another option available for applications which may
require very light weight PV modules; it consists of a 4 mm front glass + 1 mm tedlar
(Polyvinyl Fluoride), resulting in a very light weight option that can be integrated for a
component such as brise soleils.
While almost all glass on glass
units are frameless for an
aesthetic integration within
any structural system, the
glass/tedlar composition
requires framing at the
perimeter with an aluminum
channel to provide it more
rigidness.

4.2.- Shapes
Crystalline silicon glass-on-glass units can also provide interesting design options through
different shapes. While the rectangular is the most frequent, trapezoids and non-regular
shapes are also available. As an example, see the picture below showing a hexagonal,
crystalline silicon glass-on-glass unit, installed at the Denver Botanic Gardens, Colorado,
USA. The rear glass contains a black colored frit pattern for enhanced aesthetics.
Hexagonal PV glass on glass unit to clad the
pyramidal building on the right. Design by Onyx
Solar.
Pyramidal design at Denver Botanic Gardens. Design and renderings by Burkett
Design/Studio NYL.

4.3.- Transparency
In contrast to the amorphous, the crystalline
silicon is composed of solid opaque
photovoltaic cells that are not customizable
(the cell have standard sizes of 5” and 6”).
The spacing of the cells, however, is
customizable, which is how the transparency
is accomplished with the crystalline units.
Similar to the amorphous, the higher the
transparency required the less power output
installed due to the less number of cells per
unit. The pictures on the right are examples
of how these two technologies can be used.
The top right picture is from a canopy
project in PA with the Mono-crystalline. It
consists of larger spacing between the PV
cells to allow more natural light to be
transmitted through. In comparison, the
picture on the bottom right shows a canopy
project in Morocco where the smaller gaps
between the PV cells provide the shading
while still allowing a substantial amount of
the natural light to filter through to radiate
the space underneath.
Larger spacing of solar cells, more day lighting, lower efficiency
per SqFt.
Smaller spacing of solar cells, less day lighting, more sun control,
higher efficiency per SqFt.

4.4.- Performance
The performance of a photovoltaic glass will depend on the following elements:
- Efficiency of the technology (refer to slide #10, solar cells)
- Geographical parameters (i.e. latitude, longitude, altitude)
- Azimuth (is the compass direction from which the sunlight is coming)
- Maintenance
Measurement conditions (Standard Testing Condition)
To evaluate the efficiency of a PV glass, the electrical characteristics must be tested under the following
standard condition:
-1000 W/m²
- AM 1.5 global (air mass coefficient defines the direct optical path length through the Earth's
atmosphere)
- 25°C
Output values to measure:
- Short circuit current (Isc)
- Open circuit voltage (Voc)
- Maximum output (Pmpp)
- Current at Pmpp (Impp)
- Voltage at Pmpp (Vmpp)
- Fill factor (FF)
- Efficiency (useful power output/total power output)

4.4.- Performance
Crystalline Silicon technology performs the best under the direct sunlight and is one of the
most efficienct solar technologies. Therefore, its performance significantly decreases
when installed under shadows or overcast weather. So it is very important to configure
the most suitable angular positioning and orientation of the unit, as well as the
geographic location of the project in order to ensure the best performance.

4.5.- Applications
One of the most effective ways that the crystalline technology can be utilized is when it is
integrated onto a large surface area which does not require much transparency. Since it
performs better when exposed to the direct sunlight, canopies, skylights, parking lots and
other roof applications are ideal integration options; notwithstanding, vertical
applications such as ventilated façades or spandrel glass for curtain walls are also
interesting options. Let’s see some examples.

Crystalline Silicon Skylight system installed in New Jersey for a large Pharmaceutical Corporation. PV Glass shows a 30% light
transmission, providing diffuse, natural illumination inside the office building.
CRYSTALLINE SILICON GLASS ON GLASS SKYLIGHTS
Skylights are also a good application for the
crystalline technology as it will often be
exposed to the direct sunlight irradiation that
it requires while simultaneously providing
filtered natural light for the interior.

Crystalline Silicon Skylight system installed in New Jersey. Open-able system counting on perforated solar cells.
CRYSTALLINE SILICON GLASS ON GLASS SKYLIGHTS

This PV Canopy is made of mono-crystalline Silicon solar cells embedded into two layers of fully tempered, laminated glass. The rear
glass incorporates a white color ceramic frit pattern which covers the shape of the solar cells.
CRYSTALLINE SILICON GLASS ON GLASS CANOPIES
Canopies are also a good applications as it
often requires shades and the protection from
the weather elements more than
transparency. Transit stations, such as shown
here at BART’s Union City Station are great for
this application.

Record: each module of this PV Canopy in Morocco has the capacity to produce a peak power of 626Wp; equivalent to 160
Wp/sqm, which means 16% of efficiency.
CRYSTALLINE SILICON GLASS ON GLASS CANOPIES

This PV Brise Soleil at Arcadia University’s main building a sun control and free electricity from the sun through innovation in design.
A TV screen monitors the Wh generated by the system and the amount of CO2 Kg eliminated. A highly educational installation.
CRYSTALLINE SILICON GLASS ON GLASS BRISE SOLEILS

This PV Brise Soleil, installed in Kona, Hawaii, incorporates a dotted ceramic frit on the rear glass pane, enhancing its aesthetics while
providing additional sun control. Given the high electricity rates in Hawaii, this installation helps reducing the high electricity bill
monthly.
CRYSTALLINE SILICON GLASS ON GLASS BRISE SOLEILS

Crystalline Silicon glass on glass units are also available for PV Parking lots. Considering electrical vehicles are becoming more and
more popular each day, a PV parking lot can be aesthetically pleasant and feed the electric vehicle charging station whenever
required.
CRYSTALLINE SILICON GLASS ON GLASS PARKING LOTS

Crystalline Silicon glass on glass installed as photovoltaic curtain wall in Punta Arenas, Chile. Due to the city’s geographic location,
the crystalline silicon solar cells receive a great amount of direct sunlight, turning it into a very efficient solution. Gaps between the
solar cells are larger for more light transmission.
CRYSTALLINE SILICON GLASS ON GLASS CURTAIN WALL
Double glazing units with Air or Argon fills are
frequently required for curtain wall
applications, providing thermal isolation as
required.

5.- STRUCTURAL/FRAMING SYSTEMS
The photovoltaic glass units do not require framing system any different from that of the
conventional glass. This allows the adaptability and multi-functionality as to where and how
the PV glass is utilized.

But how does the junction box work with the insulating glass unit spacer?
That is a typical question many designers have. In an effort to maintain the aesthetics of
photovoltaic glass and to provide clean installations, the IGU will be shifted few millimeters to
make a space for the junction box. This way, the junction boxes are placed behind the front
glass lamination, and hidden behind the structural system receiving the photovoltaic glass.
Alternatively, the edge connection junction box could be another option, but it must be
reviewed accordingly with the structural system proposed.
Below are the images that illustrate how the junction boxes are located to accommodate
the structural detail. The image on the left shows a composition without the junction box and
the right image is with the junction boxes.

Typical curtain wall detail, normal glass. Typical curtain wall detail, photovoltaic glass.

Photovoltaic glass is compatible with all types of commercial profiles available on the market
such as Kawneer, Schuco, Reynaers, Oldcastle, YKK…
Minor adjustments or additions must be made to the system, especially depending on how
the wire is handled throughout the structure of a curtain wall. The installation method must
adapt to whether the wire runs through the conduit or it runs inside the structural profile itself.
The figure of top right demonstrates a typical detail of a mullion system which incorporates a
bolted L-channel to hide the junction box and the wiring along the structure of the curtain
wall. Typically, the L-profile’s color would match the color of the mullion system selected.
*This is just an example of one of the structural solutions available. Other applications may
not require relocating junction box, additional structural systems, or modifications.

Crystalline Silicon glass on glass
units are also available for PV
parking lots. Considering
electrical vehicles are
becoming more and more
popular each day, a PV
parking lot can be
aesthetically pleasant and
feed the electric vehicle
charging station whenever
required.

An alternative design for photovoltaic curtain wall. The figure above illustrates a PV
curtain wall which incorporates a wire conduit anchored to the mullion system to
run all wiring up to the combiner boxes. This is an alternative way to address the
wiring of the installation.

PV Ventilated Facade’s structural detail. Primary and mounting structures. Ventilated
facade structures usually receive and withstand the photovoltaic glass incorporating a
clip/clamp system as shown in the figure above.

A typical mounting system for a PV Parking Lot.

PV Parking Lot typical structural system. Compatible with both amorphous Silicon and
crystalline Silicon glass on glass units.

A PV paver supporting system. PV pavers can be supported on different raising systems. The
figure above illustrates a traditional PVC pedestal, anchored/fixed to the ground level. It fixes
and supports the PV Glass pavers while gathering the wiring. Notwithstanding the image above,
there are other raising systems available depending on the structural needs of each project.
Steel and aluminum channels can be another option to raise the pavers whenever they are
larger in size and therefore heavier.

6.- ELECTRICAL BALANCE OF SYSTEM:
MAIN COMPONENTS
6.1.- Energy Management alternatives
A. Direct consumption with battery
B. Direct consumption
C. Connecting to the grid system

6.- ELECTRICAL BALANCE OF SYSTEM:
MAIN COMPONENTS
A Solar PV Balance-of-System or BOS refers to the components and equipment that
move DC energy produced by the solar panels through the conversion system which, in
turn, produces AC electricity.
Most often, BOS refers to all components of a PV system other than the modules. In
addition to inverters, this includes the cables/wires, switches, enclosures, fuses, ground
fault detectors, and more. BOS applies to all types of solar applications (i.e.
commercial, residential, agricultural, public facilities, and solar parks).

6.- ELECTRICAL BALANCE OF SYSTEM: MAIN
COMPONENTS
Image above shows a typical electrical one-line diagram / electrical design for the PV glass
installation. Count on your electrical engineers and also on your PV glass supplier to help you
with additional information in this field.

Collecting solar properties and generating electricity with the PV glass integration
provides the following three options as to how the power output can be managed:
A. Direct consumption with battery: This is a
useful option where the PV integration will
generate more power than what is consumed.
The battery can store the surplus electricity for
later use. The batteries, however, with its
installation is costly and is less environmentally
friendly.

B. Direct consumption: When power output from
the PV glass integration is less than the
consumption, it may be best to choose this option.
At a hospital building, for instance, where the
energy consumption is high, it is better to
simultaneously feed the power source in real time
than otherwise. Since this does not require
batteries, it is more environmentally friendly and
less costly.

C. Connecting to the grid system: This could be
a viable option for a large scale community
development, for instance, where the larger
entity could produce a great amount of energy
collectively. The grid system would also allow for
one individual to sell the harvested energy to
others who are connected to the system.

7.- LEED CERTIFICATION/GREEN BUILDING
ELEMENTS
The PV glass integration solution provides numerous effective ways in which LEED
certification can be attainable. The following is the break-down of how the PV integration
can help in earning the LEED credits:
Location and transportation (LT):
LT CREDIT: BICYCLE FACILITIES: Promote bicycling and transportation efficiency and reduce
vehicle distance traveled. To improve public health by encouraging utilitarian and
recreational physical activity.
LT CREDIT: GREEN VEHICLES : Reduce pollution by promoting alternatives to conventionally
fueled automobiles.
Sustainable Sites (SS):
SS CREDIT: HEAT ISLAND REDUCTION: Roof and non-roof.
Reduces heat island to minimize its impact on
microclimate and habitats of people, animals, and plants.

Indoor Environmental Quality (EQ):
EQ CREDIT: THERMAL COMFORT: Provides a comfortable thermal environment that
promotes occupant productivity and well-being.
EQ CREDIT: DAYLIGHT: Provides building occupants with a connection between indoor
spaces and the outdoor through the introduction of daylight and views into the regularly
occupied areas of the building.
EQ CREDIT: QUALITY VIEW: Give building occupants a connection to the natural outdoor
environment by providing quality views.
EQ CREDIT: ACCOUSTIC PERFORMANCE: Provide workspaces and classrooms that promote
occupants’ well-being, productivity, and communications through effective acoustic
design.
ELEMENTS

Energy & Atmosphere (EA):
EA CREDIT: RENEWABLE ENERGY PRODUCTION: Encourages and recognizes increasing
levels of on-site renewable energy to reduce environmental and economic impacts
associated with fossil fuel energy use.
Innovation (IN):
IN CREDIT: INNOVATION: Encourage projects to achieve exceptional or innovative
performance
ELEMENTS

8.- PHOTOVOLTAIC GLASS SPECIFICATIONS
Photovoltaic Glass is commonly specified within the following three sections:
263100 – Photovoltaic Collectors
088000 – Glazing
088800 – Special Function Glazing
Depending on the spec writer, section 263100 can be complemented with sections 088000 or
088800 whenever required, depending on the type of application, or just refer to these glazing
sections to get more information about the photovoltaic collectors.
Each spec writer has his or her way of writing the spec. As the glazing industry evolves and building
integrated photovoltaic applications are being widely adopted, it is now very frequent to get the
glass specified under these glazing sections.
For special photovoltaic glass applications, such as the PV floor pavers, there are other possible
sections where the PV paver is specified, such as:
09600 – Flooring
That is without prejudice to find it specified within any of the sections previously mentioned.

8.- PHOTOVOLTAIC GLASS SPECIFICATIONS
The following links show the specs for three different photovoltaic glass units:
1.- Amorphous Silicon photovoltaic glass
http://www.onyxsolardownloads.com/docs/Onyx-Solar-CSI-Specifications-Example-I-Triple-laminate-thin-film-f.pdf
2.- Crystalline Silicon photovoltaic glass
http://www.onyxsolardownloads.com/docs/Onyx-Solar-CSI-Specifications-Example-II-double-laminated-
Crystallyne-glass-f.pdf
3.- Amorphous Silicon photovoltaic floor paver
http://www.onyxsolardownloads.com/docs/Onyx-Solar-CSI-Specifications-Example-III-Walkable-floor-f.pdf
These three documents show examples of the standard photovoltaic glass specification.
When specifying photovoltaic glass, sizes and thicknesses will be adjusted as needed. It
should be noted that all glass thickness and interlayer thickness can be adjusted as required.
For applications requiring a different interlayer, coating, and heat treatment, the spec
should incorporate that information the same way as the spec for a traditional glass.
It is advisable however to count on a photovoltaic glass fabricator whenever doubts arise,
to help specifying PV glass the right way.

9.- COST INFORMATION AND RETURN ON THE
INVESTMENT
9.1.- Cost information
9.2.- Return on the investment

COST OF THE PV GLASS: the cost of photovoltaic glass varies depending on:
1.- Total PV Glass SqFt. Keep in mind that PV Glass production is more economic when
ordering in large quantities. The saving can be up to 70% compared to small PV glass orders.
Therefore, commercial developments, office buildings, large retail projects, and educational
are normally much more interesting for photovoltaic glass than a residential project.
2.- PV Glass dimensions. This course shows several of the most standard and cost competitive
glass sizes available on the market. However, custom sizes are also available on demand to
meet any project requirement. Whenever you can stick to a standard size, cost will be 8 – 16%
cheaper than a customized size. Consider this fact early in the design phase!
Photovoltaic glass is not merely a construction material but also a great source of green
building design that brings a very interesting investment.
The elements below show the main cost streams to consider when designing a building
integrated photovoltaic.

3.- PV Glass buildup. Monolithic glass is less expensive than a low-e double glazing. PV Glass
price also depends on build ups. The more complex the photovoltaic glass is, the more
expensive. Let’s work with the right buildup that meets your performance requirements!
Prices can range from $4/Sqft for 1/8” + 1/8” laminated PV glass, up to $22/Sqft for
photovoltaic double glazing units. In between there is a wide range of options. The pricing
may vary for special compositions with extra thick glass lites, special shapes and so on.
Notwithstanding, that is a huge range and the best way to estimate the cost for the PV glass,
is to count on a photovoltaic glass fabricator that will quote the glass according to project
needs.
*COST OF THE STRUCTURAL SYSTEM: photovoltaic glass is normally frameless, and as
commented previously, it is compatible with most commercial framing/structural systems in
the market. Therefore, there are no extra costs associated to the framing system, since the
same system that receives normal glass would receive photovoltaic glass also. Only in the
cases where an additional plate or channel to hide the wires is required, there would be a
small addition in the cost. However, for estimating purposes, you can consider no added
costs for the framing system.

COST OF THE ELECTRICAL BALANCE SYSTEM: the cost of the electrical installation depends
on the energy management business model selected (direct consumption, self
consumption with backup, grid connected). Depending on that model the cost of the
electrical equipment required will be evaluated: inverters, protections/fuses, combiner
boxes, wires…
The industry normally ballparks the cost using the $/Wp ratio. That ratio reflects a dollar
amount per watt installed; Watts installed will be given by the nominal power of the PV
Glass per Sqft times the total Sqft of the project.
Once the size of the photovoltaic glass installation is selected, it is advisable to count on
an electrical contractor to quote the electrical installation. The installation is similar to a
traditional photovoltaic system, so expect an installation cost similar to a traditional system.
Certain photovoltaic glass manufacturers can also provide quotes on the electrical
installation, whenever they have capabilities of delivering turnkey projects. Count on them
since they will be able to guide you.

9.2.-Return on the investment
Photovoltaic glass pays off. Ask yourself:
What is the return on the investment for a traditional glazing?
The answer is none. There is no return on the investment for a traditional glazing. A building
enclosure can be designed specifying an energy efficient glass with sun control coatings.
That glass will cost more than, for example, a single pane unit. It would possibly provide
savings in HVAC systems but not return on the investment.
Photovoltaic glass, on the other hand, allows for the decrease on the operation and
management costs, especially associated with HVAC systems since it is an energy efficient
glazing. On top of that, it generates electricity from the sun. The generated solar electricity
will prove its value on the electricity bill of the building. This is the active property of the
photovoltaic glass that makes it a multifunctional glazing for any construction project.
In order to calculate the return on the investment for a photovoltaic glazing, the following
premises have to be taken into consideration:

1.- NET INVESTMENT:
+ The cost of the PV glass installation
– The cost of the traditional glass installation
= Net Investment
2.- INPUTS TO CALCULATE RETURN ON THE INVESTMENT
*Electricity Production over the lifespan of the installation (25 to 30+ years)
*Cost of electricity and projected cost increases over 25 to 30+ years)
*Expenses in HVAC systems vs. savings due to the energy efficient PV Glass installation
*Operation and Management costs for the PV Glass system
*Tax incentives and rebates (35% Federal Tax Credit of the total cost of the photovoltaic
system + State & Local incentives via rebates or performance-based).

The return on the investment may vary between each project according to its regional
electricity price its state and local incentives. However, the photovoltaic glass will always pay
off.
While the following evaluation shows a less “tangible” benefits associated with the
photovoltaic glass incorporation for the building, they have been stated as a fact by third
party research and consulting firms:
* Enhanced productivity level associated with the building incorporating green and energy
efficiency measures.
* Higher property market value
* Higher asking rents
* Enhanced corporate image and social responsibility
* Exposure to P.R. and media due to the innovative approach to incorporate solar energy

10.- DESIGNING YOUR ENVELOPE WITH PV GLASS.
GENERAL RECOMMENDATIONS.
Congratulations if you are about to design your next architectural project with a photovoltaic
glazing. That means you are up to date on the new technologies and new glazing trends for
the building envelope, which has turned into a key part of building design to optimize the
energy efficiency, to promote comfort and wellbeing, and to decrease operation and
management costs of the building.
1.- Whenever possible, bring on board a photovoltaic glass manufacturer to assist you during
the early design phases of the project. They will be able to help you with CAD drawings,
constructive details, photovoltaic glass design, and solar technologies to consider applications
and initial estimated figures (costs, energy yield). They will normally do it for free, at least at the
early estimating and design phase, since their goal will be to help you spec the photovoltaic
glass.
2.- Think of PV Glass as a normal architectonic glass that generates free electricity for your
building. In this sense, almost any U-value, SHGC, reflectance will be achieved by photovoltaic
glass. Ask a photovoltaic glass manufacturer about the PV glass buildup that will match your
performance requirements.

GENERAL RECOMMENDATIONS
3.- Think of your whole building as a source for generating energy. Using photovoltaic glass
allows you to generate electricity not only from the rooftop of your building, but also from
curtain walls and façades, skylights, canopies, louvers and fins, balustrades and so on.
All these applications will allow for your design to raise awareness of the sustainable materials
your building incorporates. While no one can see you are generating free electricity from the
rooftop, everyone will take notice of the PV building envelope.
4.- Solve your questions while advancing in the design of your building skin. The earlier you learn
about the PV glass limitation (size, thickness, output, treatments), the earlier you will complete a
fully manufacturable design. Call your PV Glass supplier and get assistance from A to Z during
the design process.

5.- Rely only on technologies that have been already proven in the market. Many PV Glass
suppliers keep developing new solar technologies to bring to the market –which is great and
something we also work hard with- however for few of those technologies it may still be early.
Check out websites of BIPV companies, see their experience, see the projects they have
completed, who their customers are, and what solar technologies they have offered. That will
give you an idea of which technologies are robust as of today and which ones are still under
development. As of today, thin film technology and crystalline solar cells are two of the most
reliable ones for BiPV applications. Notwithstanding, keep a lookout for us for upcoming
developments!
6.- Whenever possible, stick to the companies that can provide you services beyond the mere
supply of the photovoltaic glass. Incorporating a new product in your building for the first time
may call for an ample assistance. Build relationships with companies willing to go the distance
with the whole design process and that will support you with more than just the cost estimation.
7.- Think big; as exposed previously, the cost of the PV Glass decreases significantly when
installing in large quantities. This is why commercial developments, office towers, mixed-uses
are usually very suitable for the PV glass.

8.- Combining glazing is always an option, too. Within the same curtain wall system, you can
combine different types of photovoltaic glass (i.e. opaque glass for the spandrel areas and
semi-transparent for the vision panes). You can also combine normal glass with PV Glass. There
are a lot of design options. Keep all of them in mind!
9.- Understand the advantages and benefits that a photovoltaic glass can bring to your
building, to share them with the whole team so that they all can understand the value
proposition of a BIPV application.
10.- Enjoy and learn from the design process; architecture, building materials and regulations
evolve quickly; being able to design buildings with the latest technologies is always a plus. We
are glad participating in your education in BiPV and happy to see you have just earned your
AIA Learning Unit!

11.- TOOLS
11.1.- Energy Modeling Tool
11.2.- Photovoltaic Estimation Tool

11.1.- Energy Modeling Tool
How it works
This tool allows you to calculate the energy and cost
savings in a building by using PV glass, thereby allowing
you to see the reduction of energy demand. Two simple
steps, selecting the location and dimension of the
building, will help you to know in a few seconds the
amount of energy saved in a building thanks to the
passive properties of the glass and the amount of
energy produced by its active properties.
The PV glass is the only building material that provides
return on the investment by generating clean electricity
throughout the year. This is made possible by the multi-
functionality of the PV glass: in addition to the on-site
solar electricity generation, it allows for the entry of
natural light into the building, reducing the need for
artificial lighting; it filters the harmful ultraviolet and
infrared radiation, which also preserves the interior of the
building; it provides thermal/acoustical insulation to
minimize the solar factor/SHGC, making the PV glass the
best choice for accomplishing the HAVC energy saving
by optimizing the indoor temperature.
ESTIMATE
NOW

11.2.- Photovoltaic Estimation Tool
How it works
Enter the value for the photovoltaic installation area
you have in mind, then select the type of the
photovoltaic technology. The result will display the
energy that would be generated and its
equivalences in avoided CO2 emissions, hours of light
and electric car mileage.
Use the screen of your smartphone or computer to
simulate the active surface of the photovoltaic glass,
and just place it in the same position that your
installation would be. The results will vary according to
the angular positioning and the orientation of the
device. Try it out and compare the results for different
design purposes.
ESTIMATE
NOW

How it works
You will be able to calculate the U-value (or thermal
transmittance) of your PV glass system. This
magnitude is important because it indicates the
heat lost through a glazing component. In this
sense, it relates directly to energy efficiency: the
lower the U-value, the greater the thermal insulation
and therefore the greater efficiency level.
In order to calculate this value, it will be required to
know the number of glass layers that makes the
composition of the glazing, characteristics of the air
space (if applicable) and the characteristics of the
encapsulant sheets used to laminate the glass.
ESTIMATE
NOW

CASE STUDY.- PHOTOVOLTAIC VENTILATED
FAÇADE
The following study was made for a 40.000 sq. feet (4.000 sq. mts.) façade from a real
prototype of 2.280 sq. feet (280 sq. mts.). This project was executed in Avila (Spain) using
amorphous silicon technology, and doing a combination between dark glasses and glasses
with a degree of 20% transparency.
These are 3+3 laminated glasses, of 1245 x 635 mm and a nominal power of 62 Wp/m² for
dark glasses and 38 Wp/m² for the semitransparent ones.

FAÇADE
The project is divided into two façades. The first one, Southeast (azimuth -45º) and the
second one, Northeast (azimuth -135º). Power installed: 11.9 kWp. Generated energy:
8.207 kWh/year, which is a 32% contribution to the total energy consumption of the
building.
On the other hand, given the insulation
properties of the ventilated façade, 53% of
the yearly energy needs of the building’s
HVAC (heating, ventilating and air
conditioning) has been saved.
The building, with a 280 m² of surface area,
has an average consumption of 193
kWh/m², of which 50% is destined for HVAC
needs.

FAÇADE
The façade was initially conceived with porcelain stoneware. When this façade was
substituted by a photovoltaic glass ventilated façade, the investment rose 20%. This
investment is amortized in 28 months and shows an Internal Rate of Revenue, i.e. the
average future yield, of 89%. In a way, throughout the service life of this installation a 30
fold of the investment is received.

This concludes The American Institute of
Architects Continuing Education Systems Course
Diego Cuevas
Onyx Solar Group
1123 Broadway
New York, NY 10010 – USA
usa@onyxsolar.com
www.onyxsolar.com

AIA_PV_GLASS_EN (1)

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