Enphase Energy, Inc.

Patent Trials and Appeals Board

Jan 11, 2021

2020001438 (P.T.A.B. Jan. 11, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
14/249,465 04/10/2014 Michael Harrison EE117 9581
54698 7590 01/11/2021
MOSER TABOADA
1030 BROAD STREET
SUITE 203
SHREWSBURY, NJ 07702
EXAMINER
TAN, RICHARD
ART UNIT PAPER NUMBER
2849
NOTIFICATION DATE DELIVERY MODE
01/11/2021 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
docketing@mtiplaw.com
llinardakis@mtiplaw.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
_________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
__________

Ex parte MICHAEL HARRISON,
ERIK WEYKER, and MARTIN FORNAGE
_________

Appeal 2020-001438
Application 14/249,465
Technology Center 2800
___________

Before ADRIENE LEPIANE HANLON, JEFFREY B. ROBERTSON, and
JAMES C. HOUSEL, Administrative Patent Judges.

HANLON, Administrative Patent Judge.

DECISION ON APPEAL

A. STATEMENT OF THE CASE
The Appellant1 filed an appeal under 35 U.S.C. § 134(a) from an Examiner’s
decision finally rejecting claims 1–14 and 16–20. We have jurisdiction under
35 U.S.C. § 6(b).
We AFFIRM.
The claims on appeal are directed to a method for voltage clamping a
photovoltaic (PV) module (claims 1–8), an apparatus for clamping a voltage of a

1 We use the word “Appellant” to refer to “applicant” as defined in 37 C.F.R.
§ 1.42. The Appellant identifies the real party in interest as Enphase Energy, Inc.
Appeal Brief dated June 24, 2019 (“App. Br.”), at 3.
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PV module (claims 9–14 and 16), and a system for clamping a PV module voltage
(claims 17–20).
Representative claim 1 is reproduced below from the Claims Appendix to
the Appeal Brief. The limitations at issue are italicized.
1. A method for voltage clamping a photovoltaic (PV) module
comprising:
measuring a DC voltage across an output of the PV module that
is coupled across an input of a power converter, wherein the PV
module comprises a plurality of substrings of PV cells;
comparing the measured DC voltage to an overvoltage
threshold;
determining the measured DC voltage exceeds the overvoltage
threshold; and
operating a clamping circuit to clamp at least a portion of the
DC voltage by clamping a subset of substrings of the plurality of
substrings.
App. Br. 14.
The Examiner maintains the following grounds of rejection on appeal:
(1) claims 1–8 under 35 U.S.C. § 103 as unpatentable over Kraft et al.2 in
view of Burghardt et al.3 and Lai et al.;4
(2) claims 9–14 and 16 under 35 U.S.C. § 103 as unpatentable over Kraft
in view of Burghardt; and
(3) claims 17–20 under 35 U.S.C. § 103 as unpatentable over
Khajehoddin et al.5 in view of Kraft and Burghardt.
B. DISCUSSION

2 US 2013/0049710 A1, published February 28, 2013 (“Kraft”).
3 US 2013/0094112 A1, published April 18, 2013 (“Burghardt”).
4 US 2012/0230066 A1, published September 13, 2012 (“Lai”).
5 US 2010/0236612 A1, published September 23, 2010 (“Khajehoddin”).
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The Examiner finds Kraft discloses a voltage clamping method comprising
the following steps: (1) measuring a DC voltage across an output of a string of PV
modules; (2) comparing the measured DC voltage to an overvoltage threshold; (3)
determining the measured DC voltage exceeds the overvoltage threshold; and (4)
operating a clamping circuit to clamp at least a portion of the DC voltage. Final
Act. 4–5.6
To illustrate, Kraft Figure 2A, reproduced below, shows a string 202 of PV
or solar modules 204. Kraft ¶ 25.

Kraft Figure 2A illustrates a portion of solar system 200
in accordance with an embodiment of the invention.
Kraft discloses that pathways 206 and 208 indicate possible locations where
a device may be used to bypass one or more modules under open circuit
conditions. Kraft ¶ 25.

6 Final Office Action dated January 24, 2019.
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The Examiner finds Kraft does not disclose that a “plurality of substrings of
PV cells are formed in a PV module.” Final Act. 3 (emphasis added). In other
words, the Examiner finds that Kraft does not disclose that the clamping circuit is
operated by clamping a subset of substrings of the plurality of substrings of PV
cells in the PV module as recited in claim 1. See App. Br. 14 (reciting that the step
of “operating a clamping circuit to clamp at least a portion of the DC voltage” is
carried out “by clamping a subset of substrings of the plurality of substrings [of PV
cells in the PV module]”). Rather, Kraft clamps a subset of the plurality of PV
modules (e.g., modules 204A and 204B) in string 202.7 See Kraft Fig. 2A.
Nonetheless, the Examiner finds Burghardt discloses a plurality of
substrings of PV cells formed in a single PV module. Final Act. 3, 5–6; see also
Burghardt Fig. 5 (showing module strings MS1, MS2, MS3, and MS4 in PV
module M1). The Examiner concludes that it would have been obvious to one of
ordinary skill in the art to modify Kraft based on the teachings in Burghardt to
form a plurality of substrings of PV cells in a PV module as claimed. Final Act. 3,
6; see also Kraft ¶ 2 (disclosing that “[a] plurality of photovoltaic cells may be
included in a solar module [(e.g., module 204)]). The Examiner finds that the
motivation for forming a single PV module as taught by Burghardt is “to reduce a
require[d] step to connect the plurality of PV modules or to provide a compact
package.” Final Act. 3, 6.

7 Referring to Appellant’s Figure 2, the Appellant discloses that the voltage
clamping circuit 220 is depicted for multiple substrings of PV cells (205, 210, and
215) in one embodiment of the invention. Spec. ¶ 26. In another embodiment of
the invention, similar to Kraft, the substrings (205, 210, and 215) may represent
three full 60-cell PV modules. Spec. ¶¶ 26–27.
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The Appellant argues that “Burghardt does not disclose, teach, or suggest
independently controlling the module substrings such that a subset of them are
operated on.” App. Br. 8. Instead, the Appellant argues that Burghardt teaches
that switch elements SS1, SS2, SS3, and SS4, respectively connected across
module strings MS1, MS2, MS3, and MS4, are either all opened or all closed
based on an enable signal FS. App. Br. 8. Therefore, the Appellant argues that the
combination of Kraft and Burghardt “teaches a plurality of solar modules coupled
to one another to form a string of solar modules, each solar module having a
plurality of module strings MS1–MS4 coupled in series and controlled (i.e.,
coupled to or decoupled from the solar module connection lines) as a single unit.”
App. Br. 8 (emphasis added).
The Appellant’s argument is not persuasive of reversible error. Claim 1
recites the step of “operating a clamping circuit to clamp at least a portion of the
DC voltage by clamping a subset of substrings of the plurality of substrings.” App.
Br. 14 (emphasis added). Claim 1 does not exclude clamping more than one subset
of substrings of the plurality of substrings as disclosed in Burghardt.
Moreover, in the rejection on appeal, the Examiner merely relies on
Burghardt to show that a plurality of substrings of PV cells are known to be formed
in a single PV module and those substrings (MS1, MS2, MS3, and MS4) are
known to be connected to individual switch elements (SS1, SS2, SS3, and SS4,
respectively). Final Act. 3, 5–6; see also Burghardt Fig. 5. The Examiner finds,
and the Appellant does not dispute, that Kraft discloses independently controlling
the PV modules in the disclosed solar system. Ans. 5;8 see also Kraft Fig. 2A.
Thus, in the modification proposed by the Examiner, the PV module(s) in Kraft’s

8 Examiner’s Answer dated October 18, 2019.
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system would be modified to include a plurality of substrings of PV cells as
disclosed in Burghardt and those substrings would be independently controlled as
disclosed in Kraft.
In response, the Appellant argues for the first time in the Reply Brief that the
Examiner’s motivation for combining Kraft and Burghardt “is directly in contrast
to the teachings of Kraft” and “[t]here is nothing additional to be gleaned from
Burghardt’s disclosure” because “Kraft already discloses that a PV module
comprises multiple PV cells.” Reply Br. 2.9
According to 37 C.F.R. § 41.41(b)(2), “[a]ny argument raised in the reply
brief which was not raised in the appeal brief, or is not responsive to an argument
raised in the examiner’s answer . . . will not be considered by the Board for
purposes of the present appeal, unless good cause is shown.”
Significantly, the Appellant’s arguments are not responsive to an argument
raised for the first time in the Examiner’s Answer. See Final Act. 6 (finding that
the motivation for combining Kraft and Burghardt is “to reduce a require[d] step to
connect the plurality of PV modules or to provide a compact package”); Final Act.
4 (recognizing Kraft discloses that “‘a plurality of photovoltaic cells may be
included in a solar module’”). Moreover, the Appellant does not show good cause
why the arguments could not have been raised in the Appeal Brief. For those
reasons, the Appellant’s arguments are untimely and will not be considered on
appeal.
Based on the foregoing, a preponderance of the evidence of record supports
the Examiner’s conclusion of obviousness in the rejection of claim 1. The
Appellant does not present arguments in support of the separate patentability of

9 Reply Brief dated December 16, 2019.
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any of claims 2–14 and 16–20. See App. Br. 9–11 (arguing that the cited
combination of references does not render obvious independent claims 9 and 17 for
the same reason that the cited combination of references does not render obvious
independent claim 1); App. Br. 9–11 (arguing that the dependent claims are not
obvious because independent claims 1, 9, and 7 are not obvious). Therefore, the
obviousness rejections of claims 1–14 and 16–20 are sustained.
C. CONCLUSION
The Examiner’s decision is affirmed.
In summary:

Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1–8 103 Kraft, Burghardt,
Lai
1–8
9–14, 16 103 Kraft, Burghardt 9–14, 16
17–20 103 Khajehoddin,
Kraft, Burghardt
17–20
Overall
Outcome
1–14, 16–20

No time period for taking any subsequent action in connection with this
appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).
AFFIRMED