Tigo Energy Innovations LLC v. SolarEdge Tech Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Tigo Energy Innovations LLC (Texas)
  • Defendant: SolarEdge Technologies, Inc. (Delaware); SolarEdge Manufacturing Inc. (Delaware)
  • Plaintiff's Counsel: Dorsey & Whitney LLP; Cherry Johnson Siegmund James PC
• Case Identification: 7:26-cv-00329, W.D. Tex., 08/19/2026
• Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Defendant SolarEdge Technologies maintains a physical place of business in the district via a manufacturing facility in Austin, Texas, either directly or through its agent, Flex Ltd. The complaint also alleges SolarEdge conducts business and has committed acts of infringement in the district.
• Core Dispute: Plaintiff alleges that Defendant's solar power optimizers and inverters infringe a portfolio of eight patents related to module-level control, communication, and safety shutdown functionalities in photovoltaic (PV) systems.
• Technical Context: The lawsuit concerns module-level power electronics (MLPE), a critical technology in modern solar energy systems that enhances safety through features like "rapid shutdown" and improves energy yield by optimizing the performance of individual solar panels.
• Key Procedural History: The complaint alleges that Defendant had pre-suit knowledge of at least some of the asserted patents through its participation in the SunSpec Alliance, an industry group where the patents were disclosed. The complaint also notes that several of the asserted patents have survived inter partes review (IPR) challenges at the Patent Trial and Appeal Board (PTAB), with those decisions being affirmed in part by the Federal Circuit.

Case Timeline

Date	Event
2006-01-01	Defendant SolarEdge founded (approximate date)
2008-10-20	Earliest Priority Date for '021, '770, '403, and '278 Patents
2009-03-25	Earliest Priority Date for '241 Patent
2009-09-18	Earliest Priority Date for '172 Patent
2009-12-01	Earliest Priority Date for '321 and '385 Patents
2012-09-25	'172 Patent Issued
2014-10-14	'241 Patent Issued
2015-01-13	'321 Patent Issued
2017-11-01	SunSpec Member's Briefing allegedly providing notice of '172 and '321 Patents
2017-11-07	'021 Patent Issued
2018-11-20	'385 Patent Issued
2019-04-09	'770 Patent Issued
2020-06-16	'403 Patent Issued
2021-05-03	IPR petitions against '321 and '770 Patents dismissed after settlement
2021-05-20	Plaintiff's predecessor (TE) identified additional patents, including the '770 Patent, as relevant to SunSpec RSD Specification
2022-01-18	'278 Patent Issued
2025-06-02	SolarEdge reported production of 250,000 inverters at Austin, TX facility
2026-01-02	Plaintiff sent letter to SolarEdge notifying it of the Tigo Patents
2026-08-19	Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,274,172 - "Systems and Method for Limiting Maximum Voltage in Solar Photovoltaic Power Generation Systems"

• Patent Identification: U.S. Patent No. 8,274,172, "Systems and Method for Limiting Maximum Voltage in Solar Photovoltaic Power Generation Systems," Issued September 25, 2012 Compl. ¶45

The Invention Explained

• Problem Addressed: The patent's background section describes the challenge of connecting multiple solar modules in series without exceeding regulatory and safety voltage limits, such as 600V in the U.S. Compl. ¶46 '172 Patent, col. 1:21-34 This limitation inhibits installers from creating longer, more cost-effective strings of panels.
• The Patented Solution: The invention proposes a system that monitors voltage along a "string bus" and actively limits the voltage contribution from one or more individual solar modules to ensure the total string voltage does not surpass a predefined safety or regulatory threshold Compl. ¶46 '172 Patent, abstract This control can be performed by a central controller or by local management units associated with each module, allowing the system to operate closer to the maximum allowable voltage without risking over-voltage conditions '172 Patent, col. 2:1-12
• Technical Importance: This technology allows for the design of more flexible and powerful solar arrays by enabling longer strings of solar panels, which can reduce balance-of-system costs while maintaining compliance with electrical safety codes Compl. ¶46

Key Claims at a Glance

• The complaint asserts method claim 17 Compl. ¶151
• The essential elements of independent claim 17 are:
  • A method comprising: monitoring a voltage across a string bus section connecting a solar module to a voltage output; and
  • limiting the voltage output based on a maximum regulatory safety voltage by limiting a voltage of the solar module.
• The complaint does not explicitly reserve the right to assert dependent claims for the '172 Patent.

U.S. Patent No. 8,860,241 - "Systems and Methods for Using a Power Converter for Transmission of Data Over the Power Feed"

• Patent Identification: U.S. Patent No. 8,860,241, "Systems and Methods for Using a Power Converter for Transmission of Data Over the Power Feed," Issued October 14, 2014 Compl. ¶47

The Invention Explained

• Problem Addressed: The patent addresses the cost and complexity of installing separate wiring for data communication in photovoltaic systems, which is needed to monitor and control individual modules Compl. ¶48 '241 Patent, col. 2:1-24
• The Patented Solution: The invention discloses using a controller to modulate the switching circuitry of a module's power converter. This modulation embeds data onto the DC power line itself, allowing the same wires that deliver energy from the solar panel to also carry control and monitoring data '241 Patent, abstract '241 Patent, col. 4:1-15 This technique is commonly known as power-line communication (PLC).
• Technical Importance: This approach reduces the cost and complexity of solar installations by eliminating the need for dedicated communication cables, a significant factor in the overall system expense and installation time Compl. ¶48

Key Claims at a Glance

• The complaint asserts apparatus claim 1 Compl. ¶163
• The essential elements of independent claim 1 are:
  • An apparatus, comprising: a photovoltaic energy production unit to generate electricity; and
  • a local management unit, coupled between the photovoltaic energy production unit and a string bus, the local management unit having: a controller, a voltage converter having switching circuitry, and a communication transmission modulator;
  • wherein the controller provides a control for the switching circuitry to cause the voltage converter to deliver electrical energy from the photovoltaic energy production unit to the string bus; and
  • wherein the communication transmission modulator modulates the control, provided by the controller to the switching circuitry of the voltage converter, with data to be transmitted from the local management unit over the string bus.
• The complaint does not explicitly reserve the right to assert dependent claims for the '241 Patent.

Multi-Patent Capsules

• U.S. Patent No. 8,933,321: Titled "Systems and methods for an enhanced watchdog in solar module installations," issued January 13, 2015 Compl. ¶49

  • Technology Synopsis: The '321 Patent describes a "watchdog unit" that monitors a signal from a central controller. If the signal is lost, interrupted, or a shutdown signal is received, the unit disconnects the solar module to render the array safe Compl. ¶50 This functionality is intended for emergency shutdown scenarios. The patent has survived IPR challenges Compl. ¶51
  • Asserted Claims: Independent claim 1 Compl. ¶176
  • Accused Features: The Accused Power Optimizers are alleged to be "watchdog units" that shut down when communication from the Accused Inverter (the "central controller") is lost Compl. ¶178

• U.S. Patent No. 9,813,021: Titled "System and method for enhanced watch dog in solar panel installations," issued November 7, 2017 Compl. ¶52

  • Technology Synopsis: The '021 Patent discloses a local management unit that communicates with a remote master control unit. The local unit shuts down power output in response to detecting an "anomaly," which includes a predetermined number of "skips" of heartbeat signals from the master unit Compl. ¶53
  • Asserted Claims: Independent claim 1 Compl. ¶189
  • Accused Features: The Accused Power Optimizers are alleged to be local management units that communicate with Accused Inverters (master control units). The optimizers allegedly shut down after a loss of communication, which is equated to detecting an anomaly or skipped heartbeat signals Compl. ¶191

• U.S. Patent No. 10,135,385: Titled "Identification Protocol Between a Local Controller of a Solar Module and a Master Controller," issued November 20, 2018 Compl. ¶54

  • Technology Synopsis: The '385 Patent addresses authentication between local and master controllers. The system involves local units sending identification codes to a master unit, receiving authentication of those codes, and continuing operation only after successful authentication Compl. ¶55
  • Asserted Claims: Independent claim 10 Compl. ¶202
  • Accused Features: The "pairing" process between the Accused Power Optimizers and Accused Inverters is alleged to practice the claimed authentication method, where the inverter authenticates the optimizers before they begin normal operation Compl. ¶204

• U.S. Patent No. 10,256,770: Titled "System and Method for Enhanced Watch Dog in Solar Panel Installations," issued April 9, 2019 Compl. ¶56

  • Technology Synopsis: The '770 Patent describes a distributed solar architecture with master and local management units. The local units can independently shut down if communication with the master unit is lost or if an emergency is detected by a sensor connected to the master unit Compl. ¶57 The patent has had claims both invalidated and upheld in IPR proceedings Compl. ¶58
  • Asserted Claims: Independent claim 1 Compl. ¶215
  • Accused Features: The Accused Power Optimizers (local units) and Accused Inverters (remote units) are alleged to form an infringing system. The SafeDC system, which shuts down the optimizers upon loss of communication or arc detection, is alleged to be the claimed shutdown-on-anomaly feature Compl. ¶217

• U.S. Patent No. 10,686,403: Titled "System and Method for Enhanced Watch Dog in Solar Panel Installations," issued June 16, 2020 Compl. ¶59

  • Technology Synopsis: The '403 Patent discloses a photovoltaic panel with a control unit that receives heartbeat signals from a remote unit. The controller detects an anomaly in the signals (e.g., skips) and, in response, reduces or shuts down the panel's power output Compl. ¶60
  • Asserted Claims: Independent claim 10 Compl. ¶228
  • Accused Features: The Accused Power Optimizers are alleged to be the claimed control units that communicate with the remote Accused Inverter. The SafeDC system is alleged to implement the claimed shutdown function in response to an anomaly in communications Compl. ¶230

• U.S. Patent No. 11,228,278: Titled "System and Method for Enhanced Watch Dog in Solar Panel Installations," issued January 18, 2022 Compl. ¶61

  • Technology Synopsis: The '278 Patent discloses a "watchdog unit" with a local controller that monitors communication from a remote central controller. If the communication is interrupted for a period longer than a number of "allowed skips," a switch disconnects the solar module from the power bus Compl. ¶62
  • Asserted Claims: Independent claim 1 Compl. ¶241
  • Accused Features: The Accused Power Optimizers are alleged to be the watchdog units, and their shutdown via the SafeDC feature upon loss of communication from the Accused Inverter is alleged to be the claimed disconnection in response to an interruption longer than the allowed skips Compl. ¶243

III. The Accused Instrumentality

Product Identification

The complaint identifies SolarEdge's "Accused Products" as its solar power optimizers (including S-Series, P-Series, and U-Series), inverters (including Home Hub, Home Wave, and Nexis models), and associated software and firmware Compl. ¶11 Compl. ¶67 Compl. ¶71

Functionality and Market Context

• The Accused Products form a "DC-optimized" solar energy system. The Accused Power Optimizers are module-level DC/DC converters that attach to individual solar panels to perform Maximum Power Point Tracking (MPPT) for each panel, which is alleged to mitigate power losses from shading or module mismatch Compl. ¶70 Compl. ¶80-82 These optimizers are connected in series to form a "string," which feeds DC power to an Accused Inverter Compl. ¶77
• The Accused Inverter converts the DC power from the string to grid-compatible AC power and also functions as the system controller and communications gateway Compl. ¶83-84 Communication between the optimizers and inverter occurs via power-line communication (PLC) over the same DC wiring that carries the power Compl. ¶86-87
• A key accused feature is SolarEdge's "SafeDC" or "rapid shutdown" functionality. Each Accused Power Optimizer is configured to reduce its output to a safe 1-volt level unless it receives a "fail-safe signal" from a functioning inverter Compl. ¶93 Compl. ¶96 When the inverter is shut down or communication is lost, the optimizers default to this safe state, thereby de-energizing the array Compl. ¶94 The complaint presents a diagram from SolarEdge marketing materials that illustrates the SafeDC feature Compl. ¶94, p. 24
• The complaint alleges SolarEdge is a "global leader in renewable energy technology" and has shipped over 140 million power optimizers and 6.9 million inverters, generating millions of dollars in revenue Compl. ¶65 Compl. ¶75-76

IV. Analysis of Infringement Allegations

8,274,172 Infringement Allegations

Claim Element (from Independent Claim 17)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A method comprising: monitoring a voltage across a string bus section connecting a solar module to a voltage output; and	A SolarEdge system includes a string bus carrying energy from solar modules. The Accused Inverters monitor voltage across this string bus section during operation.	¶152a	col. 6:29-31
limiting the voltage output based on a maximum regulatory safety voltage by limiting a voltage of the solar module.	The Accused Inverters limit the voltage output of the Accused Power Optimizers to comply with regulatory safety standards. During rapid shutdown, the optimizers enter "SafeDC mode," ceasing to provide normal string voltage.	¶152b	col. 2:1-12

8,860,241 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
An apparatus, comprising: a photovoltaic energy production unit to generate electricity; and	Each Accused Power Optimizer is used with a PV panel that generates electricity.	¶165b	col. 4:1-2
a local management unit, coupled between the photovoltaic energy production unit and a connection of energy production units forming a string bus, the local management unit having: a controller, a voltage converter having switching circuitry, and a communication transmission modulator;	The Accused Power Optimizers are alleged to be local management units coupled between PV panels and a string bus. They allegedly contain a microcontroller (controller), a buck/boost converter with MOSFETs (voltage converter with switching circuitry), and PLC circuitry (communication transmission modulator).	¶165c; ¶165e; ¶165f; ¶165g	col. 4:1-15
wherein the controller provides a control for the switching circuitry to cause the voltage converter to deliver electrical energy generated by the photovoltaic energy production unit to the string bus; and	The controller in the Accused Power Optimizers allegedly sends control signals to gate drivers to cause the buck/boost converter to deliver energy from the PV panel to the string bus.	¶165h	col. 4:8-11
wherein the communication transmission modulator modulates the control, provided by the controller to the switching circuitry of the voltage converter, with data to be transmitted from the local management unit over the string bus.	The PLC circuitry allegedly modulates the control signal provided by the microcontroller to the switching circuitry of the buck/boost converter, with data to be transmitted over the string bus.	¶165i	col. 4:11-15

Identified Points of Contention

• For the '172 Patent, a central issue may be whether the accused SafeDC feature meets the limitation "limiting the voltage output based on a maximum regulatory safety voltage." The complaint alleges the feature ensures compliance with regulatory standards Compl. ¶152b, but the accused system's trigger appears to be a loss of a "keep-alive" signal from the inverter Compl. ¶96, not a direct measurement or calculation related to a specific regulatory voltage. The court may need to determine if a fail-safe mechanism that has the effect of maintaining regulatory compliance is "based on" that regulation as the claim requires.
• For the '241 Patent, the infringement allegation hinges on the specific mechanism of the accused PLC. The claim requires the "communication transmission modulator" to "modulate[] the control, provided by the controller to the switching circuitry." This raises the technical question of whether the Accused Products' PLC circuitry modulates the actual gate drive signals for the power conversion MOSFETs, or if it superimposes a separate, high-frequency carrier signal onto the power line. The latter is a common PLC method that may not meet the specific language of the claim, creating a potential point of dispute. The complaint offers a diagram of the accused system architecture, which may provide evidence on this point Compl. ¶84, p. 21

V. Key Claim Terms for Construction

For U.S. Patent No. 8,274,172:

• The Term: "limiting the voltage output based on a maximum regulatory safety voltage"
• Context and Importance: This term is the functional core of claim 17. The infringement case for the '172 Patent depends on whether the accused SafeDC feature, which reduces optimizer voltage to 1V upon loss of an inverter signal Compl. ¶96, performs a limitation that is "based on" a regulatory voltage. Practitioners may focus on this term because SolarEdge could argue its feature is based on the presence or absence of a communication signal, not a voltage level, and its compliance with regulations is a consequential effect, not the basis of operation.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent specification repeatedly discusses the goal of preventing voltage from exceeding "regulatory or safety limits" '172 Patent, abstract '172 Patent, col. 2:9-12 This language may support an interpretation where any control scheme designed with the purpose of ensuring regulatory compliance is "based on" that regulation.
  • Evidence for a Narrower Interpretation: The claim requires the limiting action to be "based on a maximum regulatory safety voltage." This could be construed to require that the limiting decision involves a comparison with, or a calculation using, the specific numerical value of the regulatory voltage, rather than a simple response to a lost communication signal.

For U.S. Patent No. 8,860,241:

• The Term: "communication transmission modulator modulates the control, provided by the controller to the switching circuitry"
• Context and Importance: This term defines how data is transmitted. The infringement allegation maps this to the accused PLC circuitry Compl. ¶165g Compl. ¶165i The dispute will likely center on the precise technical method of the accused PLC. Practitioners may focus on this term because a common PLC technique involves superimposing a high-frequency carrier signal onto the power line, which could be argued to be separate from "the control" signal for the power converter, potentially placing it outside the literal scope of the claim.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent's abstract states the invention's purpose is "Transmission of Data Over the Power Feed" by modulating "the control ... with data." This broad statement of purpose could support reading the claim to cover any method where the power converter's electronics are manipulated to send data over the power line.
  • Evidence for a Narrower Interpretation: The claim language is highly specific: it is "the control" for the "switching circuitry" that is modulated. This could be argued to require that the data signal be embedded by directly altering the PWM (pulse-width modulation) signal that drives the power converter's transistors, as distinct from adding a separate carrier signal that merely shares the same wire.

VI. Other Allegations

• Indirect Infringement: The complaint alleges that SolarEdge induces infringement by "intentionally instructing, encouraging, and assisting" installers and customers to assemble and operate the Accused Products in an infringing manner through installation manuals, software tools (e.g., SetApp), and technical support Compl. ¶14 Compl. ¶99-102 Compl. ¶156 Contributory infringement is alleged on the basis that the Accused Products are material parts of the inventions, are especially adapted for use in an infringing manner, and are not staple articles of commerce with substantial non-infringing uses Compl. ¶14 Compl. ¶157
• Willful Infringement: The complaint alleges willful infringement based on both pre-suit and post-suit knowledge. Pre-suit knowledge is alleged to have been acquired no later than November 1, 2017, through SolarEdge's active membership in the SunSpec Alliance, where certain Tigo patents were disclosed in connection with the rapid shutdown standard Compl. ¶107-109 Compl. ¶112 Knowledge is also alleged based on a direct notification letter sent from Tigo to SolarEdge on January 2, 2026 Compl. ¶110 Willfulness is based on SolarEdge's alleged "deliberate and intentional" decision to continue its accused activities after acquiring this knowledge Compl. ¶114-116

VII. Analyst's Conclusion: Key Questions for the Case

• A core issue will be one of functional interpretation: does SolarEdge's "SafeDC" feature, a fail-safe mechanism triggered by the loss of a "keep-alive" signal, perform the function of "limiting ... based on a maximum regulatory safety voltage" as required by the '172 Patent? The case may turn on whether a system designed to achieve regulatory compliance as an outcome is legally equivalent to a system that uses the regulatory value as a direct input for its control logic.
• A second central issue will be a technical and definitional one: does SolarEdge's power-line communication system infringe the '241 Patent by "modulat[ing] the control" of its power converter's switching circuitry, or does it employ a non-infringing method, such as superimposing a separate data carrier onto the power lines? The outcome will depend on the court's construction of the claim term and the specific technical evidence regarding the operation of the accused PLC.
• A third key question will relate to damages and willfulness: did SolarEdge's participation in the SunSpec Alliance, where Tigo's patents were disclosed, provide the level of specific, pre-suit knowledge required to support a finding of willful infringement? This will likely involve a factual inquiry into the nature of the disclosures and what a sophisticated industry participant like SolarEdge knew or should have known.