SolarEdge Technologies Ltd v. SMA Solar Technology AG

1. Case Identification

• Case #: IPR2020-00965
• Patent #: 8,779,630
• Filed: June 16, 2020
• Petitioner(s): SolarEdge Technologies Ltd.
• Patent Owner(s): SMA Solar Technology, AG.
• Challenged Claims: 1-23

2. Patent Overview

• Title: Power Generation System and Inverter for Feeding Power into a Three-Phase Grid
• Brief Description: The ’630 patent discloses a power generation system, such as a solar power system, with a specific relay arrangement for disconnecting the system from a three-phase electrical grid. The alleged invention is a relay arrangement comprising three two-pole relays, configured to provide two serially connected, independently activated switches for each of the three grid phases, intended to meet safety standards requiring protection against "islanding" (unintentionally feeding power to a downed grid).

3. Grounds for Unpatentability

Ground 1: Obviousness over Sakae and Burr - Claims 1-6, 11, 14, 15, and 17-19 are obvious over Sakae in view of Burr.

• Prior Art Relied Upon: Sakae (Japanese Patent Publication No. 2003-116222) and Burr (Application # 20080079318).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Sakae taught a solar power generation system connected to a three-phase grid via a DC/AC inverter, which is the system recited in independent claim 1. Sakae’s relay arrangement included two three-pole relays (switches 11 and 12) for grid disconnection, providing two series-connected switches for each phase. This configuration, controlled by a single control unit, allegedly met most limitations of the independent claims. However, Petitioner contended that Sakae did not explicitly disclose three relays.
  • Motivation to Combine (for §103 grounds): Burr was introduced to remedy this alleged deficiency. Burr taught a safety relay system with three relay contacts connected in series to provide improved fault tolerance, explaining that if one relay contact welds shut, the others can still open the circuit. A POSITA would combine Sakae’s grid-tie inverter system with Burr's teaching of a third series relay to enhance the system's safety and fault tolerance, which was a known problem with grid-disconnection switches.
  • Expectation of Success: The combination involved adding a known component (a third relay) to an existing system (Sakae's) in a known manner to achieve the predictable result of improved safety, as explicitly taught by Burr.

Ground 2: Obviousness over Sakae, Burr, and Nitsche - Claims 7-9, 12, 16, and 20-22 are obvious over Sakae, Burr, and Nitsche.

• Prior Art Relied Upon: Sakae, Burr, and Nitsche (Application # 2008/0067877).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the Sakae and Burr combination to address limitations in dependent claims related to control and monitoring. Nitsche was cited for its disclosure of a safety switching apparatus that included a microcontroller (claimed "control unit"), a watchdog arrangement, and AND gates. Nitsche taught using the control unit and watchdog to generate setting and interrupt signals that ensure relays operate only when both control circuits are functional (claim 7), monitoring the control unit with the watchdog (claim 8), and using a test signal to monitor the relay drivers (claim 9).
  • Motivation to Combine (for §103 grounds): A POSITA would be motivated to incorporate Nitsche's advanced safety and monitoring features into the Sakae/Burr system. Since the relays in Sakae perform a critical anti-islanding safety function, ensuring their reliable control is paramount. Nitsche provided a known technique for improving the reliability of similar safety relay systems.
  • Key Aspects: Petitioner also argued Nitsche taught integrating safety components into a compact housing (mapping to claims 12 and 16), a common practice for protecting electronic systems.

Ground 3: Obviousness over VDE0126 and Burr - Claims 1-5, 11, 14-15, and 17-18 are obvious over VDE0126 and Burr.

• Prior Art Relied Upon: VDE0126 (a German technical standard, DIN V VDE V 0126-1-1) and Burr.

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that the ’630 patent itself admitted its purpose was to comply with standards like VDE0126. The VDE0126 standard explicitly required a disconnection device that disconnects a generator from the grid using two independently controlled switches arranged in series for each active conductor. Petitioner argued that a POSITA tasked with implementing this standard for a three-phase system would have arrived at the claimed invention through one of a few, well-known design choices, such as using six single-pole relays, two three-pole relays, or three two-pole relays.
  • Motivation to Combine (for §103 grounds): The motivation was to simply design a system compliant with the VDE0126 standard. Choosing between the limited, known relay configurations to achieve compliance was an obvious design choice. The combination with Burr provided the explicit motivation to select a three-relay configuration (over a minimal two-relay configuration) to achieve the enhanced fault tolerance and safety that Burr taught.
  • Expectation of Success: A POSITA would have a high expectation of success in implementing a known safety standard using a finite and well-understood set of commercially available relay configurations.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds adding Spreitzer (German Patent No. DE 100 29 828 C1) for teaching relay testing via a short-duration test pulse, and Finder (a technical datasheet) for teaching PCB-mountable relays. Other grounds mirrored the logic of the grounds above but used VDE0126 as the primary reference instead of Sakae.

4. Key Claim Construction Positions

• "photovoltaic inverter" (claims 3, 15): Petitioner proposed this term be construed as “an inverter that converts the DC output of a photovoltaic solar panel into an AC source for a power grid,” consistent with the Applicant’s argument during prosecution.
• "the relay arrangement is integrated into a housing" (claims 12, 16): Petitioner proposed this term be construed to mean the relay arrangement is “located inside” a housing, arguing this reflects the plain meaning and context in the patent, as opposed to a more complex "merged" or "fused" interpretation.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the grounds for review should not be denied under §314(a) or §325(d) because they were not cumulative with arguments considered by the examiner during prosecution. The petition also noted the filing of companion petitions and stated the asserted grounds were not redundant with those presented in the other petitions.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-23 of Patent 8,779,630 as unpatentable.