{"product_id":"eg4-flexboss21-21kw-split-phase-hybrid-solar-inverter","title":"EG4 FlexBOSS21 21kW Split-Phase Hybrid Solar Inverter","description":"\u003cstyle\u003e\n.flexboss21-pd {\n  --ink: #000000;\n  --ink-2: #141414;\n  --paper: #F7F7F7;\n  --card: #FFFFFF;\n  --text: #000000;\n  --text-light: #FFFFFF;\n  --muted: #5C5C5C;\n  --accent: #246AAF;\n  --accent-2: #36AF24;\n  --line: #E2E2E2;\n  --radius: 14px;\n  --font-display: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;\n  --font-mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;\n  font-family: var(--font-display) !important;\n  color: var(--text) !important;\n  opacity: 1 !important;\n  background: var(--card);\n  line-height: 1.65;\n  font-size: 16px;\n  border: 1px solid var(--line);\n  border-radius: var(--radius);\n  overflow: hidden;\n  box-shadow: 0 16px 40px rgba(16,20,25,0.10);\n}\n.flexboss21-pd, .flexboss21-pd *, .flexboss21-pd *::before, .flexboss21-pd *::after { box-sizing: border-box; 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}\n.fb21-compat li { font-family: var(--font-mono) !important; font-size: 13.3px; padding-left: 18px; position: relative; }\n.fb21-compat li::before { content: ''; position: absolute; left: 0; top: 6px; width: 8px; height: 8px; background: var(--accent-2); border-radius: 2px; }\n\n\/* FAQ *\/\n.fb21-faq { padding: 42px 32px; background: var(--paper); }\n.fb21-faq details { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 2px 18px; margin-bottom: 10px; }\n.fb21-faq summary { cursor: pointer; font-weight: 600; font-size: 14.8px; padding: 15px 24px 15px 0; list-style: none; position: relative; }\n.fb21-faq summary::-webkit-details-marker { display: none; }\n.fb21-faq summary::after { content: '+'; position: absolute; right: 0; top: 13px; font-size: 19px; color: var(--accent) !important; }\n.fb21-faq details[open] summary::after { content: '\\2013'; }\n.fb21-faq details p { padding: 0 0 16px; color: var(--muted) !important; font-size: 13.8px; max-width: 70ch; }\n\n\/* Downloads *\/\n.fb21-downloads { padding: 42px 32px; background: var(--card); }\n.fb21-download-list { display: flex; flex-wrap: wrap; gap: 12px; }\n.flexboss21-pd .fb21-download {\n  display: inline-flex; align-items: center; gap: 10px;\n  padding: 12px 18px;\n  border: 1px solid var(--line);\n  border-radius: 10px;\n  text-decoration: none !important;\n  color: var(--text) !important;\n  font-size: 14px; font-weight: 600;\n  transition: border-color .15s ease, background .15s ease;\n}\n.flexboss21-pd .fb21-download:hover { border-color: var(--accent) !important; background: var(--paper); }\n.fb21-download svg { width: 18px; height: 18px; color: var(--accent) !important; flex-shrink: 0; }\n\n\/* Footer *\/\n.fb21-footer { padding: 26px 32px; background: var(--ink); color: var(--text-light); }\n.flexboss21-pd .fb21-warranty { font-size: 14px; color: var(--text-light) !important; }\n.flexboss21-pd .fb21-warranty strong { color: var(--accent) !important; }\n\u003c\/style\u003e\n\u003cdiv class=\"flexboss21-pd\"\u003e\n\u003c!-- ============ HERO ============ --\u003e\n\u003csection class=\"fb21-hero\"\u003e\n\u003cp class=\"fb21-eyebrow\"\u003e48V Hybrid Inverter · 3 MPPT · GridBOSS-Ready · UL 9540\u003c\/p\u003e\n\u003ch2\u003e16,000 Watts of Hybrid Power, Built to Scale With EG4's GridBOSS\u003c\/h2\u003e\n\u003cp class=\"fb21-lead\"\u003eThe EG4 FlexBOSS21 is rated for 12,000W of continuous output on its own, rising to 16,000W with solar actively assisting, backed by up to 21,000W of PV input across three MPPT trackers and five solar strings. It works grid-tied or fully off-grid, integrates directly with EG4's GridBOSS energy management hub, and carries a 10-year manufacturer's warranty inside a NEMA 4X all-weather enclosure.\u003c\/p\u003e\n\u003cdiv aria-hidden=\"true\" class=\"fb21-divider\"\u003e\u003csvg preserveaspectratio=\"none\" viewbox=\"0 0 600 20\"\u003e\u003cpath stroke-linecap=\"round\" stroke-width=\"2\" stroke=\"currentColor\" fill=\"none\" d=\"M0,10 Q25,-4 50,10 T100,10 T150,10 T200,10 T250,10 T300,10 T350,10 T400,10 T450,10 T500,10 T550,10 T600,10\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c!-- ============ STATS ============ --\u003e\n\u003csection class=\"fb21-stats\"\u003e\n\u003cdiv class=\"fb21-stat\"\u003e\n\u003cspan class=\"num\"\u003e16,000W\u003c\/span\u003e\u003cspan class=\"label\"\u003ePeak Output (w\/ PV)\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-stat\"\u003e\n\u003cspan class=\"num\"\u003e21,000W\u003c\/span\u003e\u003cspan class=\"label\"\u003eMax Solar Input\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-stat\"\u003e\n\u003cspan class=\"num\"\u003e3 MPPT\u003c\/span\u003e\u003cspan class=\"label\"\u003e5 Solar Strings\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-stat\"\u003e\n\u003cspan class=\"num\"\u003e10-Year\u003c\/span\u003e\u003cspan class=\"label\"\u003eWarranty\u003c\/span\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c!-- ============ FEATURES ============ --\u003e\n\u003csection class=\"fb21-features\"\u003e\n\u003ch3\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0566\/2418\/5399\/files\/FlexBoss21-Simple-System-Expansion-Final-scaled-1-2048x820.webp?v=1784837233\" alt=\"A diagram, set against a subtle card background, shows five battery units connected in a row and integrating seamlessly with the Eco Solar Kits EG4 FlexBOSS21 21kW Split-Phase Hybrid Solar Inverter. The display uses the IBM Plex Sans font for clarity, and text highlights both effortless integration and an optional conduit box for clean, easy installation.\"\u003e\u003c\/h3\u003e\n\u003ch3\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0566\/2418\/5399\/files\/Flexboss-All-weather-Rain.webp?v=1784837256\" alt=\"At night, a modern house glows warmly in the rain, powered by lights inside and equipped with solar panels on the roof—demonstrating backup power solutions. The sleek architecture features wide windows with gently rounded corners for a contemporary look. Text in IBM Plex Sans highlights how the Eco Solar Kits EG4 FlexBOSS21 21kW Split-Phase Hybrid Solar Inverter keeps power on during outages using advanced solar energy storage technology.\"\u003e\u003c\/h3\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch3\u003eWhat Makes the FlexBOSS21 Different\u003c\/h3\u003e\n\u003cdiv class=\"fb21-feature-grid\"\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" fill=\"currentColor\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M13 2 4 14h6l-1 8 9-12h-6l1-8z\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003e12,000W Base, 16,000W With PV\u003c\/h4\u003e\n\u003cp\u003eRated for 12,000W continuous on its own, and up to 16,000W when solar is actively contributing alongside the battery.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003ccircle r=\"4.2\" cy=\"12\" cx=\"12\"\u003e\u003c\/circle\u003e\u003cpath d=\"M12 3v2M12 19v2M4.2 12H2.2M21.8 12h-2M5.6 5.6l1.4 1.4M17 17l1.4 1.4M18.4 5.6 17 7M7 17l-1.4 1.4\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003e21kW Solar, 3 MPPT \/ 5 Strings\u003c\/h4\u003e\n\u003cp\u003eThree independent MPPT trackers split across five total input strings, pulling up to 21,000W utilized from the array.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003ccircle r=\"2.5\" cy=\"12\" cx=\"6\"\u003e\u003c\/circle\u003e\u003ccircle r=\"2.5\" cy=\"12\" cx=\"18\"\u003e\u003c\/circle\u003e\u003cpath stroke-dasharray=\"2 2\" d=\"M8.5 12h7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003eGridBOSS Integration\u003c\/h4\u003e\n\u003cp\u003eConnects directly to EG4's GridBOSS hub for smart load management, AC coupling, and generator support at a system level.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M9 2v4M15 2v4M7 8h10v4a5 5 0 0 1-10 0V8Z\"\u003e\u003c\/path\u003e\u003cpath d=\"M12 17v4\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003e90A Grid Feed-Through\u003c\/h4\u003e\n\u003cp\u003eHandles high-demand loads and grid integration with headroom beyond what most residential hybrid inverters offer.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M4 7h13M13 3l4 4-4 4M20 17H7M11 21l-4-4 4-4\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003eHybrid: Grid-Tied or Off-Grid\u003c\/h4\u003e\n\u003cp\u003eUL 9540 certified for both grid-tied and off-grid installs with compatible batteries — the same unit covers either path.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M12 2 4 5v6c0 5 3.4 8.4 8 9.9 4.6-1.5 8-4.9 8-9.9V5l-8-3Z\"\u003e\u003c\/path\u003e\u003cpath stroke=\"none\" fill=\"currentColor\" d=\"M12 8c-1.5 2-2.5 3.3-2.5 4.5a2.5 2.5 0 0 0 5 0C14.5 11.3 13.5 10 12 8Z\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003eNEMA 4X All-Weather\u003c\/h4\u003e\n\u003cp\u003eRated for direct outdoor installation and built to keep running through rain and snow, not just covered or indoor spaces.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"fb21-accent-2\"\u003e\u003cpath d=\"M12 2 4 5v6c0 5 3.4 8.4 8 9.9 4.6-1.5 8-4.9 8-9.9V5l-8-3Z\"\u003e\u003c\/path\u003e\u003cpath d=\"M8.5 12.3 10.8 14.6 15.5 9.9\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003ch4\u003eRapid Shutdown \u0026amp; Fault Protection\u003c\/h4\u003e\n\u003cp\u003eBuilt-in rapid shutdown, ground fault, and arc fault protection for safe, code-compliant operation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-feature\"\u003e\n\u003csvg aria-hidden=\"true\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003crect transform=\"rotate(-18 7 12)\" rx=\"3\" height=\"6\" width=\"9\" y=\"9\" x=\"2.5\"\u003e\u003c\/rect\u003e\u003crect transform=\"rotate(-18 17 12)\" rx=\"3\" height=\"6\" width=\"9\" y=\"9\" x=\"12.5\"\u003e\u003c\/rect\u003e\u003c\/svg\u003e\n\u003ch4\u003eParallels Up to 16 Units\u003c\/h4\u003e\n\u003cp\u003eScales from a single home installation up to large residential or commercial-style systems on the same platform.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv aria-hidden=\"true\" style=\"background: var(--ink-2); color: var(--accent); opacity: 0.7;\" class=\"fb21-divider\"\u003e\u003csvg preserveaspectratio=\"none\" viewbox=\"0 0 600 20\"\u003e\u003cpath stroke-linecap=\"round\" stroke-width=\"2\" stroke=\"currentColor\" fill=\"none\" d=\"M0,10 Q25,-4 50,10 T100,10 T150,10 T200,10 T250,10 T300,10 T350,10 T400,10 T450,10 T500,10 T550,10 T600,10\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\u003c\/div\u003e\n\u003c!-- ============ NARRATIVE ============ --\u003e\n\u003csection class=\"fb21-narrative\"\u003e\n\u003ch3\u003eBuilt as the Center of a Larger System\u003c\/h3\u003e\n\u003cp\u003eThe FlexBOSS21 sits at the top of EG4's hybrid lineup by power: 12,000W continuous on its own, 16,000W when solar is actively feeding in alongside the battery, and up to 21,000W of usable PV input spread across three MPPT trackers and five separate strings. That's more granular solar tracking than a typical 2-MPPT hybrid inverter, which matters on larger or more complex roof layouts with panels facing different directions.\u003c\/p\u003e\n\u003cp\u003eWhere it distinguishes itself further is the GridBOSS ecosystem: paired with EG4's GridBOSS hub (sold separately), it gains smart load management, AC coupling for retrofits, and generator support at a whole-system level rather than just at the inverter. It's UL 9540 certified for both grid-tied and off-grid installs with BigBattery ETHOS or EG4 batteries, wrapped in a NEMA 4X enclosure rated for direct outdoor installation, and backed by a 10-year manufacturer's warranty.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003c!-- ============ SPECS ============ --\u003e\n\u003csection class=\"fb21-specs\"\u003e\n\u003ch3\u003eFull Specifications\u003c\/h3\u003e\n\u003cdiv class=\"fb21-spec-groups\"\u003e\n\u003cdiv class=\"fb21-spec-group\"\u003e\n\u003ch4\u003eOutput\u003c\/h4\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eRated output (without PV)\u003c\/td\u003e\n\u003ctd\u003e12,000 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRated output (with PV)\u003c\/td\u003e\n\u003ctd\u003e16,000 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput voltage\u003c\/td\u003e\n\u003ctd\u003e120\/240V, 120\/208V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax output current\u003c\/td\u003e\n\u003ctd\u003e66.7 A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePeak power (0.5s \/ 1s)\u003c\/td\u003e\n\u003ctd\u003e24,000W \/ 18,000W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower factor\u003c\/td\u003e\n\u003ctd\u003e0.99 (full load)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransfer time\u003c\/td\u003e\n\u003ctd\u003e20ms default \/ 10ms configurable\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-spec-group\"\u003e\n\u003ch4\u003eSolar Input\u003c\/h4\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eMPPT channels\u003c\/td\u003e\n\u003ctd\u003e3 (5 strings total)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax utilized PV power\u003c\/td\u003e\n\u003ctd\u003e21,000 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRec. max PV input\u003c\/td\u003e\n\u003ctd\u003e25,000 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDC input voltage range\u003c\/td\u003e\n\u003ctd\u003e100–600 Vdc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMPPT voltage range\u003c\/td\u003e\n\u003ctd\u003e120–440 Vdc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax efficiency (PV to grid)\u003c\/td\u003e\n\u003ctd\u003e97%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-spec-group\"\u003e\n\u003ch4\u003eBattery \u0026amp; Grid\u003c\/h4\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eNominal battery voltage\u003c\/td\u003e\n\u003ctd\u003e48 Vdc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBattery voltage range\u003c\/td\u003e\n\u003ctd\u003e40–60 Vdc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax charge\/discharge power\u003c\/td\u003e\n\u003ctd\u003e12,000 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRec. battery capacity\/inverter\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;300 Ah\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax AC bypass\u003c\/td\u003e\n\u003ctd\u003e90 A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIdle consumption\u003c\/td\u003e\n\u003ctd\u003e\u0026lt;65 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-spec-group\"\u003e\n\u003ch4\u003ePhysical \u0026amp; Environmental\u003c\/h4\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions (D×W×H)\u003c\/td\u003e\n\u003ctd\u003e11.3 × 22.3 × 30.5 in\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e88 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEnclosure rating\u003c\/td\u003e\n\u003ctd\u003eNEMA 4X (all-weather)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating temperature\u003c\/td\u003e\n\u003ctd\u003e-13°F to 140°F\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNoise level\u003c\/td\u003e\n\u003ctd\u003e\u0026lt;50 dB @ 3 ft\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDesign topology\u003c\/td\u003e\n\u003ctd\u003eHigh-frequency, transformerless\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"fb21-spec-group\"\u003e\n\u003ch4\u003eConnectivity \u0026amp; Warranty\u003c\/h4\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eCommunication\u003c\/td\u003e\n\u003ctd\u003eRS485 \/ CANBus \/ Wi-Fi\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax parallel units\u003c\/td\u003e\n\u003ctd\u003e16\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand \/ model\u003c\/td\u003e\n\u003ctd\u003eEG4 FlexBOSS21\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWarranty\u003c\/td\u003e\n\u003ctd\u003e10 years\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size: 12.5px; color: var(--muted) !important; margin-top: 18px !important;\"\u003eCertification: UL 1741, UL 9540.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003c!-- ============ COMPATIBILITY ============ --\u003e\n\u003csection class=\"fb21-compat\"\u003e\n\u003ch3\u003eBattery Compatibility\u003c\/h3\u003e\n\u003cp\u003eUL 9540 certified with closed-loop communication for both grid-tied and off-grid installs, when paired with:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBigBattery ETHOS\u003c\/li\u003e\n\u003cli\u003eEG4 280Ah All-Weather \/ Indoor\u003c\/li\u003e\n\u003cli\u003eEG4 314Ah All-Weather \/ Indoor\u003c\/li\u003e\n\u003cli\u003eRecommended: \u0026gt;300Ah per inverter\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003c!-- ============ FAQ ============ --\u003e\n\u003csection class=\"fb21-faq\"\u003e\n\u003ch3\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0566\/2418\/5399\/files\/All-EG4-scaled-1-2048x820.webp?v=1784837285\" alt=\"Promotional image showcasing the Eco Solar Kits lineup—including the EG4 FlexBOSS21 21kW Split-Phase Hybrid Solar Inverter—featuring product photos and concise descriptions on a clean white card background. The modern layout is enhanced by crisp IBM Plex Sans typography.\"\u003e\u003c\/h3\u003e\n\u003ch3\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0566\/2418\/5399\/files\/FlexBoss21-allweather-gridboss.webp?v=1784837304\" alt=\"A car sits in a garage at night alongside energy storage devices; on the right, features of the EG4 FlexBOSS21 21kW Split-Phase Hybrid Solar Inverter by Eco Solar Kits are neatly displayed in crisp IBM Plex Sans font: smart control, grid cell integration, surge capacity, self-sufficiency, and value solution—all elegantly presented within sleek panels featuring rounded corners.\"\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0566\/2418\/5399\/files\/EG4-Inverter-Certification-scaled-2-2048x820.webp?v=1784837324\" alt=\"A professional reviews UL safety certificates for inverters on a screen displayed against a sleek card backdrop. In modern IBM Plex Sans, the text announces: “Certified to Highest UL Safety Standards, UL1741: EG4 FlexBOSS21 21kW Split-Phase Hybrid Solar Inverter.” The Intertek and ETL logos appear on the left, underscoring Eco Solar Kits' commitment to quality.\"\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch3\u003eCommon Questions\u003c\/h3\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat's the difference between the 12kW and 16kW ratings?\u003c\/summary\u003e\n\u003cp\u003e12,000W is what the FlexBOSS21 delivers continuously on battery and grid power alone. 16,000W is the higher figure it can reach when solar is actively contributing at the same time — the same inverter, just with the sun helping out. Both numbers are accurate; they just describe different operating conditions.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat's the GridBOSS, and do I need one?\u003c\/summary\u003e\n\u003cp\u003eThe EG4 GridBOSS is a separate energy management hub (sold separately) that adds smart load management, AC coupling, and generator support at a whole-system level. It's an optional add-on — the FlexBOSS21 runs as a complete inverter on its own — but it's a natural pairing for larger or more complex installations.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan it really be installed outdoors?\u003c\/summary\u003e\n\u003cp\u003eYes — it carries a NEMA 4X enclosure rating, built for direct exposure to rain and snow, unlike IP20-rated inverters that require an indoor or fully enclosed location.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat batteries does it work with?\u003c\/summary\u003e\n\u003cp\u003eIt's UL 9540 certified for both grid-tied and off-grid installs with BigBattery ETHOS and EG4 batteries, with at least 300Ah of recommended capacity per inverter.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWill it run my entire house?\u003c\/summary\u003e\n\u003cp\u003eIt depends on your total connected load. At 12,000–16,000W depending on solar contribution, it covers most homes comfortably, but a full load calculation is worth doing before sizing your system, especially for larger properties with heavy HVAC or well pump draw.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I connect more than one unit?\u003c\/summary\u003e\n\u003cp\u003eYes, up to 16 units can be paralleled together, which is enough headroom to scale from a single large home up to bigger residential or commercial-style installations.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo I need a licensed electrician to install it?\u003c\/summary\u003e\n\u003cp\u003eGiven the voltages and currents involved, and the added complexity of a grid-interactive hybrid system, installation should be handled by a qualified, licensed electrician or solar installer familiar with your local code and utility interconnection requirements.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003c\/section\u003e\n\u003c!-- ============ DOWNLOADS ============ --\u003e\n\u003csection class=\"fb21-downloads\"\u003e\n\u003ch3\u003eDocuments \u0026amp; Downloads\u003c\/h3\u003e\n\u003cdiv class=\"fb21-download-list\"\u003e\n\u003ca rel=\"noopener\" href=\"https:\/\/bigbattery.com\/wp-content\/uploads\/2025\/01\/EG4-FlexBoss21-Spec-Sheet.pdf\" class=\"fb21-download\" target=\"_blank\"\u003e \u003csvg aria-hidden=\"true\" stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M12 3v12M7 10l5 5 5-5M4 19h16\"\u003e\u003c\/path\u003e\u003c\/svg\u003e Spec Sheet \u003c\/a\u003e \u003ca rel=\"noopener\" href=\"https:\/\/bigbattery.com\/wp-content\/uploads\/2025\/01\/FlexBOSS-21-Manual.pdf\" class=\"fb21-download\" target=\"_blank\"\u003e \u003csvg aria-hidden=\"true\" stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M12 3v12M7 10l5 5 5-5M4 19h16\"\u003e\u003c\/path\u003e\u003c\/svg\u003e User Manual \u003c\/a\u003e \u003ca rel=\"noopener\" href=\"https:\/\/bigbattery.com\/wp-content\/uploads\/2024\/11\/EG4-FlexBoss21-COC.pdf\" class=\"fb21-download\" target=\"_blank\"\u003e \u003csvg aria-hidden=\"true\" stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"1.7\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpath d=\"M12 3v12M7 10l5 5 5-5M4 19h16\"\u003e\u003c\/path\u003e\u003c\/svg\u003e UL1741 Certificate \u003c\/a\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c!-- ============ FOOTER ============ --\u003e\n\u003csection class=\"fb21-footer\"\u003e\n\u003cp class=\"fb21-warranty\"\u003eBacked by a \u003cstrong\u003e10-year manufacturer's warranty\u003c\/strong\u003e covering defects in materials and workmanship.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003c\/div\u003e","brand":"EG4","offers":[{"title":"Default Title","offer_id":42331530821687,"sku":"INV027","price":3599.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0566\/2418\/5399\/files\/EG4_FlexBOSS_21_Front.webp?v=1784838085","url":"https:\/\/ecosolarkits.com\/products\/eg4-flexboss21-21kw-split-phase-hybrid-solar-inverter","provider":"Eco Solar Kits","version":"1.0","type":"link"}