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EG4

EG4 FlexBOSS18 + WallMount 314Ah Indoor Battery Kit | 16–48 kWh | Self-Heating

SKU K0216

Regular price: $6,692.97

Regular price: $6,692.97

✅ Order by 12:00 PM EST and processing starts the same day (ships within 1–2 business days). Free, insured US shipping — delivery in 4–7 business days. Oversized items ship via LTL freight and we coordinate delivery with you by phone.

Product variants

Quantity

OffGrid Horizon Family Owned and Operated

🏔️ OffGrid Horizon is family-owned & off-grid obsessed. Read our story →

Shipping: how fast & how it works

Free standard shipping on every US order — no shipping charges at checkout, no hidden fees, and every shipment is insured against loss or damage.

Processing: 1–2 business days. Order before 12:00 PM EST and processing begins the same day.
Delivery: 4–7 business days via USPS, UPS or FedEx. Tracking is emailed the moment your order ships.
Large items (solar kits, batteries, shelters): delivered by LTL freight carriers such as FedEx Freight, Old Dominion or XPO. The carrier calls ahead to schedule a delivery window — please inspect the pallet and note any damage on the delivery receipt before signing, and we’ll take care of the rest.

Questions about delivery to your location? Call (302) 496-3554 (Mon–Fri, 9am–4pm EST) — we’re happy to check before you order.

What is your Return Policy?

At OffGrid Horizon, we want every customer to shop with confidence. If something doesn’t go as planned, we’ve made returns and refunds simple and fair. Here’s how it works:

1. Return Window

You can request a return within 30 days of receiving your order. Unfortunately, we’re unable to accept returns after that time frame.

2. Who Pays for Return Shipping?

If your item arrives damaged, defective, or incorrect, we’ll cover the return shipping cost — and you’ll receive a full 100% refund or replacement, including any original shipping costs.
If you’re returning an item because you changed your mind, you’ll be responsible for return shipping, and a 25% restocking fee applies.

3. Damaged or Defective Items

Received something broken or not working properly? Contact us within 30 days. We’ll provide a prepaid return label and once the item is returned and inspected, we’ll issue either a full refund or a replacement.

4. Changed Your Mind?

If you no longer want the item, you can return it within 30 days — as long as it’s unused, unopened, in its original packaging, and in resellable condition.

5. Refund Processing

Once we receive and approve your return, we’ll send a confirmation email and issue a refund to your original payment method within 7 business days. Please allow additional time for banks or credit card companies to process and reflect the refund.

How to start a return: email sales@offgridhorizon.com or call (302) 496-3554 (Mon–Fri, 9am–4pm EST) with your order number — we’ll send return instructions and your RMA right away.

Product Description

An all-EG4 indoor energy storage system: the FlexBOSS18 hybrid inverter — 18 kW of solar input and 13 kW of continuous split-phase AC output across three MPPT channels — paired with the EG4 WallMount Indoor battery, a 48V 314Ah (16 kWh) unit with UL9540A-tested design and self-heating cells for reliable cold-weather charging. Configure one to three batteries for 16, 32, or 48 kWh.

What's in this kit

1 × EG4 FlexBOSS18 hybrid solar inverter — 18 kW PV input, 13 kW continuous split-phase 120/240V output, 3 MPPT channels, grid-tied / off-grid / backup modes, and app-based Wi-Fi monitoring
Your choice of 1, 2, or 3 × EG4 WallMount Indoor 48V 314Ah batteries — 16 kWh each, UL9540A-tested, with self-heating for cold spaces
Native closed-loop communication — EG4 inverter and EG4 batteries are designed for each other

Choosing your capacity

1 battery (16 kWh) backs up essential circuits and carries an efficient household overnight. 2 batteries (32 kWh) supports whole-home backup with regular 240V loads. 3 batteries (48 kWh) is the extended-autonomy configuration for larger homes, heavy solar self-consumption, or multi-day outage coverage.

Key features

UL9540A-tested battery design — the fire-safety testing building departments look for in garage, basement, and utility-room installations
Self-heating cells keep charging available in unconditioned cold spaces — no external heater or warm room required
Single-brand ecosystem: EG4 inverter and batteries communicate natively for closed-loop operation
Split-phase 120/240V output feeds standard North American home circuits directly
Remote Wi-Fi monitoring of production and battery state from the app

Specifications

Battery	EG4 WallMount Indoor 48V 314Ah, 16 kWh per unit
Capacity options	16 / 32 / 48 kWh (1, 2, or 3 batteries)
Battery safety	UL9540A-tested design; self-heating cells
Inverter	EG4 FlexBOSS18 hybrid
Solar (PV) input	Up to 18 kW across 3 MPPT channels
AC output	13 kW continuous, split-phase 120/240V
Operating modes	Grid-tied, off-grid, battery backup
Monitoring	Remote Wi-Fi app monitoring

Warranty & support

Batteries: each EG4 WallMount 314Ah Indoor battery carries a 10-year manufacturer warranty (or 10,000 cycles, whichever comes first). Inverter: the FlexBOSS18 carries a 10-year full parts-or-product replacement manufacturer warranty. EG4 requires warranty registration within the first year of purchase (or proof of purchase from an authorized distributor) to keep coverage valid.

Common questions

Indoor or All-Weather batteries?

Choose Indoor if your batteries will live in a garage, basement, or utility room — you get UL9540A-tested design plus self-heating for cold snaps. Choose the All-Weather version of this kit if the batteries must mount outside.

Do I need an electrician?

Yes — a hybrid inverter interconnects with your main panel and, in grid-tied modes, with the utility. Installation should be performed by a licensed electrician, and home energy storage installations are subject to local permitting.

Are solar panels included?

No. Panels, racking, and array wiring are sized to your site and sold separately. The system also operates as battery backup without solar. Select your capacity from the Battery Configuration menu — pricing is for the complete kit.