CyboEnergy v. Duracell Power Center: Solar Inverter Patents Dismissed Without Prejudice
CyboEnergy, Inc. asserted two solar power inverter patents against Duracell Power Center, LLC in California’s Northern District. The plaintiff voluntarily dismissed all claims without prejudice just 93 days after filing, before the defendant had answered — leaving both patents available for future assertion.
Early voluntary exit leaves Duracell solar inverter exposure unresolved
On December 10, 2024, CyboEnergy, Inc. filed suit against Duracell Power Center, LLC in the U.S. District Court for the Northern District of California (Case No. 3:24-cv-08891), presided over by Judge Lisa J. Cisneros. The action alleged infringement of two patents — US9331489B2 and US9331488B2 — both directed to solar power inverter technology, and specifically targeted Duracell Power Center’s line of solar microinverters.
On March 13, 2025, CyboEnergy filed a notice of voluntary dismissal under Federal Rule of Civil Procedure 41(a)(1)(A)(i), which permits a plaintiff to dismiss without court order if the defendant has not yet answered or moved for summary judgment. The dismissal was explicitly without prejudice, meaning CyboEnergy retains the right to re-file the same claims. Each party bears its own litigation costs, with no fee-shifting ordered.
The 93-day lifecycle is notably short and suggests the dispute may have been resolved through early-stage negotiations, a licensing agreement, or a strategic decision to pursue litigation in a different venue or at a different time — none of which are confirmed in the public record. The without-prejudice designation is commercially significant: the patents remain enforceable and Duracell Power Center cannot claim res judicata protection from this dismissal.
Filing to Voluntary dismissal in 93 days
93 days — resolved well before typical district court timelines of 2–3 years
Voluntarily dismissed: what the Rule 41 exit means for both parties
Rule 41(a)(1)(A)(i): plaintiff’s unilateral right to exit
Federal Rule 41(a)(1)(A)(i) allows a plaintiff to dismiss an action without a court order, provided the defendant has not yet served an answer or a motion for summary judgment. CyboEnergy exercised this right 93 days after filing. Because no judicial merits determination was made, the dismissal carries no precedential weight on the validity or infringement of either asserted patent.
No merits rulingWithout prejudice: the distinction that keeps claims alive
The dismissal was expressly without prejudice, meaning CyboEnergy is not barred from re-asserting US9331489B2 or US9331488B2 against Duracell Power Center or any other party in the future. Had the dismissal been with prejudice, the plaintiff would have been permanently barred from bringing the same claims. The public record does not disclose why without-prejudice terms were chosen, but this preserves maximum enforcement optionality for CyboEnergy.
Claims may be re-filedDuracell Power Center avoids judgment — but patent risk persists
Duracell Power Center obtains no legal protection from this dismissal. The without-prejudice exit means no res judicata shield, no invalidity ruling, and no non-infringement finding. The company’s solar microinverter products remain potentially exposed to the same patents. Duracell Power Center filed no answer and incurred no recorded fee obligation, but the underlying IP risk is unresolved.
Exposure unresolvedSolar inverter IP landscape: two live patents, one open question
US9331489B2 and US9331488B2 remain in force and unlitigated to a merits conclusion. For solar microinverter manufacturers and distributors, this case signals that CyboEnergy is actively monitoring the competitive landscape. The early exit is consistent with a confidential settlement, licensing discussion, or tactical repositioning — all of which suggest the patents have perceived commercial value worth pursuing.
Patents remain enforceableFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | CyboEnergy, Inc. | Company | Solar energy technology company — holder of US9331489B2 and US9331488B2Search in Eureka ↗ |
| Defendant | Duracell Power Center, LLC | Company | Duracell Power Center, LLC — solar microinverter manufacturer and distributorSearch in Eureka ↗ |
| Plaintiff counsel | Jennifer L. Ishimoto | Attorney | Counsel for CyboEnergy, Inc.Search in Eureka ↗ |
| Plaintiff counsel | William Peterson Ramey , III | Attorney | Counsel for CyboEnergy, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Jennifer Ishimoto | Law Firm | Representing CyboEnergy, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Ramey LLP | Law Firm | Representing CyboEnergy, Inc.Search in Eureka ↗ |
| Presiding judge | Judge Lisa J. Cisneros | Judge | California Northern District CourtSearch in Eureka ↗ |
Official order — verbatim text
The dismissal notice explicitly invokes Rule 41(a)(1)(A)(i) and specifies that the dismissal is without prejudice, with each party bearing its own costs. This phrasing is legally precise: the without-prejudice designation is controlling and means no claim preclusion attaches. The cost-bearing provision — absent any fee-shifting — is neutral and does not suggest any finding of exceptional case status under 35 U.S.C. § 285. No merits determination was reached on infringement or patent validity.
US9331489B2 & US9331488B2 — Solar Power Microinverter Technology
US9331489B2 and US9331488B2 are U.S. utility patents assigned to CyboEnergy, Inc., covering solar power inverter technology — specifically microinverter systems used to convert DC power from solar panels to AC power for grid or direct consumption. The patents derive from application numbers US13/789637 and US13/537206 respectively, placing their priority in the early-to-mid 2010s, a pivotal period of growth in distributed solar generation architecture.
Microinverters represent a significant share of the residential and small commercial solar installation market, offering panel-level power optimisation versus traditional string inverters. CyboEnergy’s assertion of both patents in a single action against a branded consumer product line — Duracell Power Center’s microinverters — suggests the patents are positioned as covering core circuit or control methodology features that would be difficult to design around without fundamental architectural changes. Competitors and OEM suppliers in this space should assess their freedom-to-operate posture against both patents.
Should you run an FTO against US9331489B2 and US9331488B2?
Any company designing, manufacturing, importing, or distributing solar microinverters or related power conversion products in the U.S. market should assess its exposure to CyboEnergy’s patent portfolio. This case demonstrates active enforcement intent: CyboEnergy retained litigation counsel and filed in a major federal district. The without-prejudice dismissal means both patents are immediately available for re-assertion against the same or different defendants.
PatSnap Eureka’s FTO Search Agent can map the claim scope of US9331489B2 and US9331488B2 against your product architecture, identify design-around pathways, and surface any prior art that could support an IPR petition if invalidity is a viable defensive strategy. Given the early stage at which this case resolved, no public claim construction record exists — making independent claim analysis all the more important for companies in the solar inverter supply chain.
Run a freedom-to-operate analysis on US9331489B2 to assess your product’s exposure
Run FTO in Eureka →Similar solar inverter and clean energy patent cases in U.S. district courts
Explore related patent infringement actions involving solar power inverter and microinverter technology filed in U.S. district courts, including the Northern District of California.
What this case signals for the solar inverter IP landscape
An early voluntary exit without prejudice is rarely the end of the story — for patent holders or their competitors.
Without-prejudice dismissals preserve enforcement leverage indefinitely
CyboEnergy’s Rule 41(a)(1)(A)(i) exit does not extinguish its rights. Companies in the solar inverter supply chain should treat US9331489B2 and US9331488B2 as active enforcement risks. A dismissal without prejudice at this early stage is frequently a precursor to re-filing, licensing negotiation, or assertion against a broader defendant pool.
Pre-answer exits often signal confidential resolution — monitor for licensing activity
When a plaintiff dismisses before the defendant has answered, it typically suggests either a quick commercial resolution or a strategic pivot. Neither scenario removes the patent risk. IP and legal teams at solar power product companies should track CyboEnergy’s patent portfolio for new filings and watch for licensing program announcements targeting microinverter manufacturers.
CyboEnergy v Duracell — key questions answered
CyboEnergy asserted two patents: US9331489B2 (application US13/789637) and US9331488B2 (application US13/537206). Both cover solar power microinverter technology and were directed at Duracell Power Center’s solar microinverter product line.
The public record does not disclose the reason. CyboEnergy filed a Rule 41(a)(1)(A)(i) notice 93 days after filing, before Duracell Power Center had answered. This is consistent with early settlement, a licensing agreement, or a strategic decision to re-file elsewhere — none of which are confirmed in court documents.
No. A dismissal without prejudice under Rule 41(a)(1)(A)(i) does not bar CyboEnergy from re-filing the same claims. No res judicata protection attaches to Duracell Power Center, and no invalidity or non-infringement finding was made. Both patents remain enforceable.
The dismissal notice specifies that each party shall bear its own costs, expenses, and attorneys’ fees. No fee-shifting was ordered. This is a standard arrangement in early voluntary dismissals and does not reflect any finding under 35 U.S.C. § 285 regarding exceptional case status.
CyboEnergy accused Duracell Power Center’s solar power microinverter product line of infringing the two asserted patents. The complaint referenced Duracell Power Center’s microinverter brochure and spec sheet, indicating specific commercial products were identified in the pleadings.
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