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Fortress Power Batteries & Hybrid Inverters LFP home energy storage, Envy inverters and eSpire commercial systems
Fortress Power designs lithium iron phosphate (LFP) batteries, hybrid inverters and commercial energy storage systems for homes and businesses. Shop current Fortress Power batteries and inverters at CSE Solar USA with live pricing, or get help matching a complete storage system.
Envy True 12kWAll-in-one hybrid inverter
eForce stackable battery9.6 kWh modules, up to 28.8 kWh per stack
eVault MAX 18.5kWh51.2 V floor-standing LFP batteryProduct images: Fortress Power official product photography.
LFPLithium iron phosphate battery chemistry
UL 9540eForce, eBoost, eFlex MAX and eVault MAX
8,000Rated cycles, eVault MAX and eFlex MAX (80% DoD)
2016Founded in Pennsylvania
Fortress Power at CSE
Shop Fortress Power batteries and hybrid inverters
Current Fortress Power listings at CSE Solar USA, with live pricing and availability from our store.
Fortress Power eForce 28.8kWh Stackable Battery | Whole-Home Energy Storage System
3 × 9.6 kWh eForce modules
In Stock$10,960.00 $14,420.00
Fortress Power eVault MAX 18.5kWh | 48V LFP Battery
18.5 kWh · 51.2 V LFP · UL 9540
In Stock$5,960.00 $7,400.00
Fortress Power eBoost 16kWh Scalable Energy Storage System
16 kWh · 51.2 V LFP · IP65
In Stock$3,420.00
Fortress Power Envy True 12kW All-In-One Hybrid Inverter
12 kW at 240 V · up to 21 kW PV array
In Stock$4,884.00 $6,450.00
Fortress Power Envy 10kW Hybrid Inverter | Whole Home Solar Storage Inverter
Model FP-ENVY-10K
10 kW continuous · UL 1741 SB
In Stock$3,963.00 $5,050.00
Fortress Power Solo 6.5K Split/Single-Phase Hybrid Inverter
6.5 kW · 120/240 V split/single-phase
In Stock$1,520.00
Listed prices are CSE Solar USA prices. Availability, lead time and freight are confirmed for every order.
Product families
Fortress Power product families
Batteries, inverters, enclosures and monitoring from the current Fortress Power lineup. Choose a family to see the CSE listings.
Stackable battery
eForce
Stackable 9.6 kWh LFP modules: two or three high for 19.2 or 28.8 kWh per stack. IP65 with built-in heaters, rated for up to 8,000 cycles.
Floor-standing battery
eVault MAX
18.5 kWh, 51.2 V LFP battery. Up to 20 in parallel (370 kWh), 8,000 cycles at 80% DoD, UL 9540 listed.
Scalable battery
eBoost
16 kWh, 51.2 V LFP storage system, IP65 with heaters and rated for 8,000 cycles. Listed to UL 1973 and UL 9540.
Modular battery
eFlex MAX
5.4 kWh, 51.2 V LFP module, IP65, up to 16 in parallel (86.4 kWh). Not compatible with the legacy eFlex 5.4.
Hybrid inverters
Envy, Envy Duo 21 and Solo
Envy True 12kW (12 kW at 240 V, 200 A AC passthrough), Envy 8/10kW, Envy Duo 21 (12 kVA at 240 V or 208 V) and Solo 6.5K for 48 V battery systems.
Enclosures & monitoring
FlexTower, DuraRack and Guardian
FlexTower full-system enclosure (IP54, UL 9540), DuraRack indoor/outdoor enclosure for eFlex batteries, and the Guardian gateway that monitors Fortress batteries and Envy inverters.
How battery storage works
From solar, to storage, to your home
In a battery-backed solar system, a hybrid inverter charges the batteries from solar, powers your home and keeps essential loads running during a grid outage.
- Solar arrayPV modules produce DC power during the day.
Hybrid inverterManages solar, battery and grid power.- LFP batteryStores energy for backup and self-use.
- Home or businessLoads run from solar, battery or grid.
Illustration of a typical storage system. The exact Fortress Power inverter and battery combination for your project is confirmed against current Fortress Power documentation before you order.
Commercial & industrial
Fortress Power eSpire commercial energy storage
The Fortress Power eSpire line (eSpire Nano, eSpire Mini and eSpire 306) combines LFP battery capacity with a power conversion system for commercial and industrial sites. CSE quotes commercial storage per project.
- eSpire Mini: 81 kWh configurations, expandable to 266 kWh
- eSpire Mini listed to UL 9540, UL 9540A and UL 1741-SB
- Fortress Power C&I warranty: 10 years on eSpire systems
- Capacity, freight and commissioning scope confirmed in writing
Fortress Power ESpire Mini 30kW Inverter & 81kWh LFP Battery ESS
30 kW PCS · 81 kWh LFP
$98,989.00
In StockApplications
Where Fortress Power storage fits
Backup power
Keep essential loads running through grid outages with battery-backed solar.
Solar self-consumption
Store daytime solar and use it in the evening instead of buying from the grid.
New solar + storage
Design the inverter, batteries and enclosure together from the start.
Commercial sites
eSpire systems for commercial and industrial storage projects, quoted per site.
Why CSE Solar USA
Why buy Fortress Power through CSE Solar USA
Live pricing and availability
Prices and stock status on this page come straight from the CSE store and update with every change.
Help matching a system
Tell us your loads and goals; we confirm the Fortress battery and inverter combination before you buy.
Residential to commercial
From a single eFlex MAX module to eSpire commercial systems, quoted per project.
One supplier for the whole system
Solar panels, inverters, storage and balance-of-system from one order.
Technical resources
Fortress Power datasheets and documents
Official Fortress Power datasheets and warranty information (opens fortresspower.com).
FAQ
Fortress Power batteries and inverters: frequently asked questions
What does Fortress Power make?
Fortress Power makes lithium iron phosphate (LFP) batteries (eForce, eBoost, eFlex MAX and eVault MAX), Envy hybrid inverters, the Solo 6.5K inverter, FlexTower and DuraRack enclosures, Guardian monitoring, and eSpire commercial energy storage systems.
Where is Fortress Power based?
Fortress Power LLC is headquartered in Langhorne, Pennsylvania, and was founded in 2016.
What warranty do Fortress Power batteries have?
Fortress Power states a 10-year standard warranty on its batteries and inverters when installed by a certified installer. The eForce battery qualifies for 15 years when installed with an Envy inverter and the Guardian gateway. Warranty terms are set by Fortress Power; see its official warranty programs page.
What is the difference between eForce, eVault MAX, eFlex MAX and eBoost?
eForce uses 9.6 kWh modules that stack two or three high. eVault MAX is an 18.5 kWh floor-standing battery. eFlex MAX is a 5.4 kWh module that can be installed up to 16 in parallel. eBoost is a 16 kWh storage system. All are 48 V class LFP batteries.
Is the eFlex MAX compatible with the original eFlex 5.4?
No. Fortress Power states that the eFlex MAX is not compatible with the legacy eFlex 5.4 battery.
Can CSE quote a complete Fortress Power system or an eSpire commercial project?
Yes. Send your loads, backup goals, existing solar and delivery ZIP, or your commercial site details, and CSE will confirm the Fortress Power configuration, availability and freight before invoicing.
Are the prices on this page current?
Yes. Prices and stock status are read live from the CSE Solar USA store. Availability, lead time and freight are confirmed for every order.
Quotes & system design help
Get a quote for a Fortress Power system
Residential storage systems
Share your loads, backup goals and existing solar. CSE confirms the Fortress Power battery and inverter combination, availability and freight before invoicing.
Request a system quoteCommercial and project storage
eSpire systems and multi-unit projects: send site details, capacity target and timeline.
Request commercial pricing(702) 608-8385 | info@csesolarusa.com | Mon–Fri 7am–6pm
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Can’t find the model you need? Request a special order
Full Fortress Power catalog
All Fortress Power products at CSE Solar USA (22)
Every Fortress Power listing on CSE Solar USA. Open a product for specifications, documents and current pricing.
Batteries (7)
Fortress Power eForce 28.8kWh Stackable Battery | Whole-Home Energy Storage System
3 × 9.6 kWh eForce modules
$10,960.00 $14,420.00
In StockFortress Power eForce 19.2kWh Stackable Battery | Whole-Home Energy Storage System
2 × 9.6 kWh eForce modules
$7,960.00 $10,000.00
In StockFortress Power eForce 9.6kWh Stackable Battery | Whole-Home Energy Storage System
9.6 kWh LFP module · IP65
$4,370.00 $5,569.00
In StockFortress Power eVault MAX 18.5kWh | 48V LFP Battery
18.5 kWh · 51.2 V LFP · UL 9540
$5,960.00 $7,400.00
In StockFortress Power eBoost 16kWh Scalable Energy Storage System
16 kWh · 51.2 V LFP · IP65
$3,420.00
In StockFortress Power eFlex Max 5.4 105Ah 48V Lithium Iron Phosphate Battery
5.4 kWh · 51.2 V LFP · IP65
$1,924.00 $3,120.00
In StockHybrid inverters (5)
Fortress Power Envy True 12kW All-In-One Hybrid Inverter
12 kW at 240 V · up to 21 kW PV array
$4,884.00 $6,450.00
In StockFortress Power Envy 8kW Hybrid Inverter
Model FP-ENVY-8K
8 kW continuous · UL 1741 SB
$3,963.00 $4,829.00
In StockFortress Power Envy 10kW Hybrid Inverter | Whole Home Solar Storage Inverter
Model FP-ENVY-10K
10 kW continuous · UL 1741 SB
$3,963.00 $5,050.00
In StockFortress Power Solo 6.5K Split/Single-Phase Hybrid Inverter
6.5 kW · 120/240 V split/single-phase
$1,520.00
In StockSystem bundles (2)
Enclosures, monitoring and accessories (5)
Fortress Power FlexTower Full System Enclosure
Full-system enclosure · IP54
$1,464.00 $2,000.00
In StockFortress Power DuraRack - Indoor / Outdoor Enclosure
Enclosure for eFlex batteries · IP54
$1,460.00 $2,000.00
In StockFortress Power Guardian Gateway Battery Monitor
Monitoring gateway · Wi-Fi, Modbus, CAN
$499.99 $599.00
In StockCommercial and industrial (3)
Fortress Power ESpire Mini 30kW Inverter & 81kWh LFP Battery ESS
30 kW PCS · 81 kWh LFP
$98,989.00
In StockFortress Power Delta 125kW PCS | Commercial Inverter & Control Cabinet
Quoted per project
Request Pricing