Note: Descriptions are shown in the official language in which they were submitted.
ROOF INTEGRATED SOLAR POWER SYSTEM WITH
TOP MOUNTED ELECTRICAL COMPONENTS AND CABLES
TECHNICAL FIELD
This disclosure relates generally to photovoltaic energy production and more
specifically to solar panels and associated solar power systems configured to
be
mounted on the roof of a building for producing electrical energy when exposed
to
sunlight.
BACKGROUND
Collecting energy directly from the sun has drawn more and more interest in
the
past several years as people and industries turn to more sustainable forms of
energy
production. One way to collect energy from the sun is through the use of
photovoltaic
panels that generate electrical energy when the panels are exposed to
sunlight. Large
numbers of such panels can be erected in an array and electrically
interconnected to
generate correspondingly large volumes of electrical energy. Such photovoltaic
arrays
have been used to supply electrical power for commercial manufacturing plants,
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wineries, commercial buildings, and even domestic buildings. Such systems
unfortunately tend to be large, bulky, unsightly, and generally not
aesthetically desirable
for installation on the roof of one's home.
More recently, photovoltaic systems have been developed that are designed to
be installed on the roof of a residential home and, when installed, to present
a more
pleasing and acceptable appearance. One example is the Powerhouse brand solar
shingle from Dow Solar, which is relatively flat, installed in a manner
similar to normal
asphalt shingles, and at least to some degree resembles ordinary shingles.
These
more recent systems, while a step in the right direction, have generally been
less
acceptable than expected for a number of reasons including their tendency to
leak, their
susceptibility to large reductions in efficiency when one or a few panels of
the system
are shaded, and the difficulty of detecting and replacing defective panels
and/or
defective electrical connections beneath the panels. These systems generally
also
require large inverters in a garage or other location that convert the direct
current (DC)
electrical energy generated by the panels to alternating current (AC)
electrical energy
for connection to the public grid.
A need persists for a roof integrated solar power system that addresses the
above and other problems and shortcomings, that is suitable in appearance and
function for use on the roofs of residential homes, and that is easily
installed and easily
serviced when necessary. It is to the provision of such a system that the
present
invention is primarily directed.
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SUMMARY
Briefly described, a roof integrated solar power system is disclosed for
installation on the roof of a residential home to produce electrical energy
when exposed
to the sun. By "roof integrated" it is meant that the system also functions as
the roofing
membrane or water barrier of the building to shed water and protect the roof
deck. The
system comprises a plurality of solar modules that may or may not include a
frame, a
photovoltaic or solar panel comprising a plurality of solar cells on the
module, and an
electronics compartment or region located to one side of the solar panel. The
electronics compartment or region is generally formed in or accessible from
the top
surface of the solar module.
In one embodiment, a micro-inverter is mounted in the electronics compartment
and is electrically connected to the solar panel of the module to convert the
DC energy
produced by the solar panel to AC energy for distribution. Also located in the
electronics compartment or region and accessible from the top surface of the
solar
module is an electrical connection block for coupling the AC energy from the
micro-
inverter of the module to AC energy generated by others of the plurality of
modules in
the solar power system. The aggregated AC electrical energy generated by the
plurality
of solar modules can then be delivered to the public electrical grid, used
directly to
power appliances, or stored in a battery bank for later use.
In another embodiment, the solar modules are frameless and are attached
directly to the roof deck with appropriate fasteners. Each module of this
embodiment
has a top surface that faces away from a roof on which it is mounted. A solar
panel
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comprising an array of solar cells is disposed on the upper surface of the
module and
edge portions to the sides of the solar panel that are devoid of solar cells.
One or more
electrical components, such as a junction box, DC optimizer, smart junction
box, and/or
a micro-inverter, are disposed within the edge portions on top of the module.
Cables also are located within the edge portions on top of the module for
interconnecting the electrical components of one module to those of adjacent
modules
in the solar power system. An access panel in the form of a protective cover
strip is
configured to be attached to adjacent modules extending along their edge
portions. The
protective cover strip covers, protects, and provides access to the electrical
components
.. and cables within the edge portions atop the solar modules.
These and other features, aspects, and advantages of the system of this
disclosure will become more apparent upon review of the detailed description
set forth
below when taken in conjunction with the accompanying drawing figures, which
are
briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective partially exploded view of one module of a roof
integrated
solar panel system according to one embodiment of the invention.
FIG. la is a simplified perspective illustration of a roof integrated solar
panel
system comprising a plurality of modules according to FIG. 1 mounted on a roof
deck.
FIG. 2 is a partial cross sectional view along line 2-2 of FIG. la showing the
electronics compartment and a micro-inverter, wiring, and connection block
contained
therein.
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=
FIG. 3 is a side elevational view of two modules of the roof solar panel
system
illustrating a starter strip and a head lap between courses of solar panel
modules.
FIG. 4 is a partial cross sectional view along line 4-4 of FIG. 1a showing a
water
managing shiplap joint at the ends of two solar panel modules.
FIG. 5 is a perspective view of an alternate embodiment of the system
incorporating direct-to-deck mounted solar panels with top mounted electrical
components and wiring.
Fig. 6 is a front perspective view of the embodiment illustrated in Fig. 5
with one
protective cover strip removed to reveal electronic components and wiring.
Fig. 7 is an enlarged perspective view showing a section of a protective cover
strip being installed over electronic components and wiring of the solar panel
system of
Fig. 5.
DETAILED DESCRIPTION
Referring now in more detail to the drawing figures, wherein like reference
numerals, where appropriate, indicate like parts throughout the several views,
FIG. 1
illustrates one embodiment of a single solar module 11 of a roof integrated
solar panel
system according to the invention. The module 11 of this embodiment comprises
a
frame 12 that can be made of any appropriate material such as, for instance,
molded or
extruded plastic, aluminum, a polymer composite material, or other material
resistant to
sun and the weather. The frame has a rear edge portion 13, a front edge
portion 14, a
right end portion 16, and a left end portion 17. A photovoltaic panel 18 is
mounted to or
recessed in the top surface of the frame for exposure to sunlight. The
photovoltaic
panel 18 may conventionally comprise an array of solar cells electrically
connected
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together to form the panel or may comprise any type of photovoltaic technology
capable
of converting solar energy to electrical energy. The photovoltaic panel 18 may
be
covered with a protective material such as glass, a polymer, an epoxy, or
similar
material to protect the photovoltaic panel from the elements and to inhibit
water
leakage.
The frame 12 of this embodiment is further formed to define a recessed
electronics compartment 19 spaced from one end of the photovoltaic panel, and
that is
formed in or accessible from the top surface of the frame. A micro-inverter 21
or other
electrical component such as a junction box, smart junction box, or DC
optimizer is
contained within the electronics compartment 19 and is connected through a
wire 20 to
the photovoltaic panel 18 of the module. The micro-inverter, which is a
commercially
available product available from a number of suppliers such as, for example,
Enphase
Energy of Petaluma, California, functions to convert DC energy produced by the
photovoltaic panel 18 to AC energy, preferably at a common frequency such as
60
cycles per second (Hz). Doing the DC-AC conversion on the module itself has
been
found to be more efficient than directing aggregated DC electrical energy from
a
plurality of solar panels to a remotely located large capacity inverter
somewhere else in
a home.
The AC output of the micro-inverter is directed through wire 22 to AC
connection
block 24, also located within the electronics compartment 19 and accessible
from the
top surface of the frame. The AC connection block 24 is configured to allow
the AC
output of other modules of the system to be interconnected so that the AC
outputs of all
the modules is can be aggregated into a single AC output that can be connected
to the
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electrical grid, power appliances, or otherwise used. For example, wire 33 may
connect
to the AC connection block 24 from the micro-inverter of the next adjacent
module of the
system while wire 34 may connect to the AC connection block of a module in a
next
higher course of modules in a system. In this way, the AC output of each
module is
aggregated and can be applied through a trunk line to its eventual use.
A removable access panel 32 is sized and configured to be mounted to the top
of
the module covering the electronics compartment to provide aesthetic appeal
and to
protect components in the electronics compartment. The access panel 32 is
accessible
from the top surface of the frame. The access panel 32 can be made to match
the
frame 12 or the photovoltaic panel 18 in appearance if desired, or it may be
configured
to contrast with the frame or photovoltaic panel. In one aspect, the top
surface of the
access panel 32 can be substantially flush with the top surface of the
photovoltaic panel
18, and both the top surface of the access panel 32 and the top surface of the
photovoltaic panel 18 may or may not be substantially flush with the top
surface of the
frame 12.
The right end portion 16 of the frame 12 in this embodiment is formed with a
laterally extending overlap 27 having channels 29 formed on its underside.
Similarly,
the left end portion 17 of the frame 12 is formed with a laterally extending
underlap 28
also having channels 31 formed therealong. The channels 31 are configured to
engage
and mesh with the channels 27 when two modules of the system are connected end-
to-
end as described in more detail below. A tapered recess 26 is formed along the
underside of the front edge portion 14 of the frame 12. As detailed below, the
recess 26
is sized and configured to receive rear edge portion 13 of a like module 11 in
a next
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=
lower course of modules of a system. As a result, the modules can form a water
barrier
when assembled together on a roof deck that also provides water shedding
during rain
that protects the roof.
It will be appreciated that when a plurality of modules 11 are installed on a
roof,
.. the thickness of each module can be minimized to improve aesthetics since
the micro-
inverters are not mounted on the backs of the photovoltaic panels but rather
to their
sides and are accessible from the top of the frame. Further, if a micro-
inverter of a
module should fail or an AC connection block should require access, it is a
simple
matter to remove the corresponding access panel 32, make the needed repairs,
and
.. replace the access panel. An entire module also can be replaced if
defective simply by
removing the access panel, disconnecting the module at the connection block,
moving
it, replacing it with a new module, and rewiring the new module within the
electronics
compartment. This is in stark contrast to traditional solar shingles, which
must be
removed from the roof deck to effect repairs and are not easily replaced when
defective.
FIG. la shows a roof integrated solar power system comprising a plurality of
solar panel modules 11 installed on the deck 43 of a roof. The roof deck in
this
illustration is plywood supported by roof rafters 44 and extends upwardly at a
pitch to a
roof ridge 46. Only three modules are shown in this illustration, but it
should be
understood that a typical system may include many more modules installed and
interconnected as shown in FIG. 1a. Two modules 11 are illustrated here in an
upper
course of modules while one module 11 is illustrated in a lower course of
modules. For
the lower and top right modules, the access panels 32 are shown attached and
covering
the electronics compartment 19 of these modules while the access panel 32 is
shown
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removed from the electronics compartment of the upper left module. The two
modules
11 of the top course are mounted end-to-end with the overlap 27 of the left
module
overlying and meshed with the underlap 28 of the right panel to form a
shiplap. The
modules may be secured to the roof deck 43 with nails, screws, or other
fasteners (not
shown) preferably driven through the upper edge or headlap portions of the
modules
and into the roof deck below. Fasteners also may be driven through other
portions of
the modules as needed.
As may be appreciated by one of skill in the art, the process of converting
the DC
electrical energy to AC electrical energy can produce significant heat.
Consequently,
positioning the micro-inverter 21 to one side of the photovoltaic panel 18,
rather than on
the back or below the photovoltaic panel, can be advantageous by relocating
the heat
source out from under photovoltaic components that may be affected by higher
ambient
temperatures. As a result, the modules 11 can be installed directly to the
deck 43 of the
roof rather than elevated on a frame above the deck, as with some prior art
systems, to
provide ventilation for electrical modules that are mounted on the backs or
below the
photovoltaic panels.
The upper edge or headlap portion of the module 11 in the lower course is
shown
received within the recess 26 of the upper course of modules. In this way, the
lower
edge portions of the upper course of modules overlaps the headlap portions of
a lower
course of shingles to facilitate water shedding. A starter strip 47 is affixed
to the roof
deck along the forward edges of a lowermost course of modules and fills the
recesses
26 of these modules. The starter strip may be formed of any appropriate
material such
as plastic, wood, a composite, or other material and extends along the lower
edges of
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the lowermost course of modules to provide a substrate to which the lowermost
course
of modules may be affixed along their forward edges. Sealant may be applied
between
the starter strip 47 and the modules to inhibit windblown water from
penetrating beneath
the lowermost course of modules. The wiring 20, 33, and 34 as well as any
additional
wiring may easily be routed through the frames 13 of the modules and all
electrical
connections are made within the electronics compartments 19 during
installation of a
system of modules.
FIG. 2 is a partial cross-sectional view taken along line 2-2 of FIG. la
illustrating
one configuration of the electronics compartment of a module according to this
embodiment of the invention. The frame 12 of the module 11 is shown resting on
a roof
deck 41 with the rear or headlap portion 13 of a next lower module received in
the
recess 26. The frame 12 of the upper module 11 is formed with a recessed area
38 that
defines the electronics compartment 19. A micro-inverter 21 in this case is
shown
disposed within the electronics compartment fastened to the floor of the
recessed area
in this case. Access panel 32 is shown covering the electronics compartment.
Preferably, the recessed area is formed such that an air space surrounds the
micro-
inverter 21 within the compartment to facilitate cooling of the electronics
compartment
19. In the illustrated embodiment, the access panel 32 has a forward edge
formed with
a pair of fingers 53 shaped to receive a tongue formed along the forward edge
of the
recessed area 38. In this way, the forward edge of the access panel is
securely fixed to
the frame and water leakage into the electronics compartment 19 along this
edge is
inhibited.
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FIG. 3 illustrates the starter strip 47 and overlying arrangement of modules
11 in
a solar power system of the present invention. As described above, the starter
strip is
fixed to the roof deck 41 and is received in the recess 26 of the lowermost
course of
modules of a system. The recesses along forward edges of modules in the next
higher
course of modules receives and overlaps the headlap portions of a lower course
of
modules to facilitate water shedding. FIG. 4 illustrates the end-to-end
connection
between two modules 11 in the same course of modules. The overlap portion 27
of the
left module is formed along its bottom surface with a series of ridges and
troughs that
form grooves 29 extending along the underside of the overlap. Similarly, the
underlap
portion 28 of the right module is formed along its top surface with a series
of
complementing ridges and troughs that form grooves 31 extending along the
upper
surface of the underlap portion 28. When two modules are joined end-to-end as
shown,
the grooves mesh with each other as shown in FIG. 4. This, in turn, prevents
water
from migrating laterally across the shiplap joint formed by the overlap and
underlap
portions and thereby inhibits leakage between modules in a course of modules.
The roof integrated solar power system of this invention is installed on a
roof
deck as illustrated in FIG. 1a in courses. A starter strip is installed along
the bottom
edge of the installation and the first course of modules is installed against
the starter
strip. The next higher course of modules is then installed with the grooves 26
of the
modules overlapping the rear edge or headlap portions of the lower course
modules.
Preferably, the modules of adjacent courses are staggered with respect to one
another
as shown in FIG. 1a to enhance the water shedding and leak resistant
properties of the
installed system. Any water that may seep into the shiplap joints of an upper
course is
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directed along the grooves of the joint onto the mid portion of a lower module
where it is
shed away.
As each module is installed on a roof deck, or after installation of the
entire
system, the modules are electrically connected together. This is done using
connector
blocks 24 located within the electrical compartment 19. The connector blocks
electrically connect the micro-inverters of each module in a course to the
micro-inverters
in other modules of the course through wires 33 that are hidden beneath the
modules.
Likewise, the micro-inverters of each course are connected to those of a next
higher (or
lower) course through wires 34 that also are hidden beneath the modules. In
the
preferred embodiment, the micro-inverters are electrically connected in
parallel so that
the total voltage of the system is substantially the same as the voltage of
one of the
micro-inverters while the electrical current capacity of the system is
substantially the
sum of the current capacities of all of the micro-inverters. The total
electrical energy
developed by the system can then be connected through a trunk wire, buss, or
otherwise to the public electrical grid, to appliances in the home, or other
destinations.
With the modules installed and wired, the electrical compartments of the
modules
are covered by their access panels 32 to complete the installation. The
interface
between the access panels and the top of the frame 12 can be made water tight
if
desired, so that the micro-inverter is positioned below the water barrier and
water
shedding is accomplished across the tops of the access panels during rain.
Alternatively, water may be allowed to leak into the electrical compartments
which may
be provided with appropriate drainage systems or weep holes so that the micro-
inverter
is positioned above the water barrier and the water shedding is accomplished
from
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within the electrical compartments. In the later case, vents may be formed in
the
access panels to vent heated air from within the electrical compartments to
ambience to
help maintain the temperature of the micro-inverters within acceptable ranges.
It will be appreciated, moreover, that with either configuration the primary
water
barrier provided by the frames 12 of the assembled solar power modules 11 may
not be
breached or interrupted during repairs, adjustments, or upgrades to the
electrical
components located with the electronics compartments 19, and that are
accessible from
the top of the modules 11.
Figs. 5 ¨ 7 illustrate a second or alternate embodiment of a solar power
system
wherein the solar modules also are mounted directly to a roof deck. Electrical
junctions,
electrical components, and cabling are disposed on top of and within edge
portions of
the solar modules. These electrical components are covered with access panels
in the
form of protective cover strips mounted to the modules. Referring first to
Fig. 5, a roof
integrated solar power system 51 is shown mounted to the roof deck 52 of a
home or
other structure. The solar power system 51 comprises a plurality of solar
modules 53
arranged in a matrix. Each solar module 53 has an upper surface that faces
away from
the roof. A solar panel bearing a plurality of solar cells for converting
sunlight to
electrical energy is disposed on the upper surface of the solar module. Edge
portions
55 (Figs. 6 and 7) are located to the sides of the solar panel and the edge
portions
preferably are barren of solar cells.
The solar modules in this embodiment are attached directly to the roof deck
with
appropriate fasteners. The modules may be framed or frameless solar modules or
more preferably may be lightweight flexible solar modules such as those
available from
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*
Rich Solar of Derrimut, Australia and others. In either case, the solar
modules are
mounted directly to the roof deck so that mounting rails and associated
mounting
hardware are not necessary. This greatly reduces the cost of the system. The
illustrated embodiment shows the use of lightweight flexible solar modules 53
having
grommets 58 for use in securing the modules to the roof. Of course, any other
means
for securing the solar modules directly to the roof are possible and all
should be
considered to be within the scope of the invention. Access panels 56 in the
form of
removable protective cover strips 56 cover the edges of side-by-side abutting
solar
modules for purposes detailed below.
Fig. 6 shows the solar power system 51 from its bottom edge with one of the
protective cover strips 56 removed. Electrical components 59 are seen to be
mounted
to the top of each module to the sides of the solar panels and within the edge
portions
modules. These components can be simple junction boxes or more complicated
items
such as smart junctions, DC optimizers, or inverters that convert DC
electrical energy to
AC. Such components have become increasingly smaller over time and are suited
for
use with the present invention. The electrical components are electrically
interconnected with electrical cables 61 to aggregate the electrical energy
produced by
the solar modules.
The protective cover strips 56 are sized and configured to overlie, cover, and
protect the electrical components 59 and cables 61 but to be easily removable
if needed
for service or replacement of a solar module or its electrical components. In
the
illustrated embodiment, each protective cover strip 56 comprises multiple
strip sections
56a, 56b, and 56c with the bottom ends of upper sections overlapping top ends
of lower
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sections. This provides water shedding properties and makes it easier to
handle, install,
and remove the protective cover strips when necessary. End caps 57 may be used
to
cover and seal open ends of the cover strips. It will be seen that the cover
strips 56 are
mounted on the solar modules to the sides of the solar panels and covering the
edge
portions of the modules. The cover strips 56 also are raised above the upper
surfaces
of the solar modules to accommodate the electrical components and cabling
below.
Fig. 7 is an enlarged view showing a protective cover strip section 56a being
installed. Two solar modules 53 are seen attached directly to a roof deck and
their
edges abut one another along junction 65. Electrical components 59 are secured
to the
top of each solar module along the edge portions 55 and to the side of the
solar panels
that carry the solar cells. Cabling 61 extends from both ends of each of the
electrical
components and the cabling terminates in cable connectors 63. The cable
connectors
63 are coupled to the cable connectors of lower and higher solar modules in a
column
of solar modules. In this way, the electrical energy produced by all solar
modules in
each column is aggregated.
Each electrically aggregated column can then be electrically coupled together
to
aggregate all of the electrical energy produced by the solar modules of the
solar power
system. This can be done at the top or bottom of the installation or somewhere
in-
between. For example, the electrical components of two side-by-side modules
can be
configured to couple together across the width of the installation. Once
electrical
connections and cable routing is complete, the protective cover strips 56 are
installed
over the electrical components, cabling, and connectors to protect them from
the
elements and to prevent rainwater from seeping through the junctions 65
between side-
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by-side solar modules. The protective cover strips can be secured with snaps,
screws,
spring clips, or any other technique for securing them removably to the solar
modules.
The top and bottom ends of the protective cover strips can be sealed with
appropriate
end caps 57.
Flashing 62 may be installed across the top of the installed solar power
system to
integrate it with surrounding shingles 54 and direct cascading water onto the
tops of the
solar modules. Flashing also may be used along the sides and the bottom edge
of the
installed system if desired.
The invention has been described herein in terms of preferred embodiments and
methodologies considered by the inventor to represent the best modes of
carrying out
the invention. It will be understood by the skilled artisan; however, that a
wide range of
additions, deletions, and modifications, both subtle and gross, may be made to
the
illustrated and exemplary embodiments without departing from the spirit and
scope of
the invention disclosed herein.
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