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NEXUS 48V 14.3kWh LiFePO4 Battery + APEX-6.5K Inverter | Off-Grid Home Back-Up System

SKU: K0191
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Regular price $4,535.00
Regular price $4,999.00 Sale price $4,535.00
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48V Off-Grid ESS · NEXUS + APEX-6.5K · Indoor System

14.3kWh of Off-Grid Power From a Pre-Matched Battery and Inverter Pair

This system pairs one BigBattery NEXUS 14.3kWh battery with one APEX-6.5K hybrid inverter into a single closed-loop off-grid setup — 14.3kWh of storage and 6,500W of continuous output, with two separate AC inputs so grid and generator can stay connected at the same time. It's an indoor installation for both components, built for cabins, homesteads, and off-grid homes, and it scales up to 214.5kWh on the same platform if you need more later.

14.3kWhTotal Capacity
6,500WContinuous Output
10,000WMax PV Input
214.5kWhMax Expandable

What's In This System

Two components, pre-matched and sold together.

Qty 1

BigBattery NEXUS 14.3kWh

Floor-standing 48V LiFePO₄ battery, expandable up to 15 units in parallel for 214.5kWh total.

Qty 1

APEX-6.5K Hybrid Inverter

6,500W continuous output with two separate AC inputs for simultaneous grid and generator connection.

Rewritten sentence: Three images highlight the BigBattery APEX-10K 10,000W Off-Grid Hybrid Solar Inverter (48V): one shows it mounted on an indoor wall with a sleek modern card background, another places it beside a house equipped with solar panels, and the third presents a technical diagram—utilizing clean IBM Plex Sans labels—identifying GRID, LOAD, GEN, BAT, and PV connections for seamless APEX-10K integration.

What Makes This System Different

14.3kWh NEXUS Battery

LiFePO₄ storage rated for 6,000+ cycles, with a 7.6kW continuous power rating and 270A peak discharge for 1 second.

6,500W Continuous, 13,000VA Surge

The APEX-6.5K delivers 6,500W continuously with headroom to start motors and pumps without tripping.

Solar, Grid & Generator Together

Two separate AC inputs mean grid and generator can both stay wired in at once, with solar charging independently on top.

Dual MPPT, 10kW Solar Input

Two independent MPPT trackers pull up to 10,000W combined, adjusting continuously through the day.

Expandable to 214.5kWh

Up to 15 NEXUS units can run in parallel on the same platform, for serious long-term capacity growth.

80A Pass-Through

Routes up to 80A straight to critical loads — enough to carry a well pump or HVAC run without staging separate circuits.

6,000+ Cycle Life

The NEXUS battery is rated for years of daily charge and discharge cycles before capacity meaningfully declines.

Advanced BMS Protection

Multi-layer protection on both the battery and inverter for safe, reliable day-to-day operation.

A Pre-Matched Pair, Built for Indoor Installation

Rather than picking a battery and inverter separately and hoping they communicate well together, this system ships as one closed-loop pairing: the NEXUS battery and APEX-6.5K inverter are designed and sold to work with each other directly. The APEX-6.5K's two independent AC inputs mean grid and generator can both stay connected simultaneously rather than switching between them, while solar charges through its own dual-MPPT circuit — a genuine differentiator from single-AC-input inverters like BigBattery's own APEX-10K.

Worth knowing before installing: this is an indoor system on both sides. The NEXUS battery is IP54-rated and specified for indoor, floor-standing installation — not the outdoor/all-weather rating some other BigBattery batteries carry — and the APEX-6.5K is IP20, also indoor-only. Plan for a garage, utility room, or dedicated power space rather than an outdoor enclosure. In exchange, the platform scales seriously: up to 15 NEXUS units can run in parallel for 214.5kWh of total storage, well beyond what a single unit provides.

Full Specifications

Battery — BigBattery NEXUS 14.3kWh (×1)

Capacity

System voltage 48 V
Nominal voltage 51.2 V
Chemistry LiFePO₄
Usable energy 14.3 kWh
Ah capacity 280 Ah
Cell configuration 16S1P

Charging & Discharge

Max continuous discharge current 140 A
Max continuous power 7.6 kW
Max discharge peak current 270A (1 sec)
Max charge current 140 A
Charging voltage range 53.5–57.6 V

Environmental

Charge temp range 32–113°F
Discharge temp range -4–113°F
Optimal discharge temp 59–95°F
Humidity range 10–95%, no condensation
Protection rating IP54, indoor floor-standing

Physical & Other

Weight ~315 lbs
Dimensions (W×H×D) 19.7 × 27.5 × 15.7 in
Communications RS485, RJ45, CAN
Max connections 15 parallel (214.5kWh)

Inverter — APEX-6.5K (×1)

Output

Rated output power 6,500 W
Max output (surge) 13,000 VA
Output voltage 120/240 Vac split-phase
Motor load capacity 4 HP
Switching time 10 ms (typ.)

Solar & Charging

MPPT channels 2 (1+1)
Max solar input power 5,000W + 5,000W
Max solar charge current 140 A
MPPT tracking efficiency 93%

AC Input & Bypass

AC inputs 2, grid + generator (simultaneous)
Bypass overload current 40 A
Pass-through capacity 80 A

Physical & Other

Dimensions 25.51 × 16.14 × 5.51 in
Weight 48 lbs
Protection rating IP20, indoor only
Parallel capacity Up to 6 units, 3-phase at 3+

Certifications: UL1741, RoHS, FCC Part 15 Class B, IEC62109-1/2.

Other Configurations Available

This same NEXUS and APEX-6.5K platform is sold in several sizes. The row below highlighted in your brand color is the configuration this page describes — everything else is shown for reference if a customer needs a different scale.

Tier Inverters Batteries Capacity Max Output
Standard 14.3 kWh 6.5 kW
Standard 28.6 kWh 6.5 kW
Standard 42.9 kWh 6.5 kW
Large 28.6 kWh 13 kW
3-Phase 42.9 kWh 19.5 kW

Common Questions

What exactly is included in this system?

One BigBattery NEXUS 14.3kWh battery and one APEX-6.5K hybrid inverter, sold as a pre-matched closed-loop pair — 14.3kWh of storage and 6,500W of continuous output.

Can this system be installed outdoors?

No — both components are indoor-rated. The NEXUS battery is IP54 and specified as indoor floor-standing, and the APEX-6.5K inverter is IP20. Plan for a garage, utility room, or dedicated indoor power space.

Can solar, grid, and a generator all connect at once?

Solar and one AC source at a time — but the APEX-6.5K's two separate AC inputs mean grid and generator can both stay wired in simultaneously, with solar charging independently on its own circuit. That's different from single-AC-input inverters, which can only use grid or generator, not both together.

Will this run my entire house?

It depends on your total connected load. At 6,500W continuous (13,000VA surge) it covers most efficient homes and cabins, but a full load calculation is worth doing before sizing your system — especially with well pumps, electric heat, or several large appliances running together.

Can I expand this system later?

Yes — up to 15 NEXUS battery units can run in parallel for 214.5kWh of total capacity, and additional APEX-6.5K inverters can be paralleled up to 6 units (3+ forming a three-phase output) for more power.

What's the warranty on this system?

The NEXUS battery carries a 12-year manufacturer's warranty and the APEX-6.5K inverter carries a 5-year manufacturer's warranty — two separate coverage periods for the two components.

Do I need a licensed electrician to install it?

Given the voltages and currents involved, installation should be handled by a qualified, licensed electrician or solar installer familiar with your local code requirements.

Documents & Downloads

Battery — BigBattery NEXUS

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Order Confirmation:

Upon completing your order, you will promptly receive an email confirming the order placement, indicating that we have received your order and pre-authorized your credit card for the purchase. Our next step is to contact our suppliers to confirm the item's availability and readiness for shipment. Should the item be on backorder or unavailable, we will notify you of the estimated lead time. If the provided lead time is unsatisfactory, we will cancel the pre-authorization and contact you via email or phone. If the item can be shipped within 5 business days, we will proceed with processing the charges and shipping your order.

Incorrect Shipping Information:

In the event of incorrect shipping information provided at checkout, we will make every effort to track down the item using our shipping partners. Please be aware that refunds and returns are not available in such cases. However, we will do our utmost to locate the item. If successful, re-shipping fees of up to 20% of the item's value may apply.

Order Shipment:

If your order is in stock and we have successfully processed your credit card charges, the items will be shipped within five business days from the order date. You will receive tracking information via email within 24 hours of your order leaving the distribution center. Should tracking information not be received within six days of your order, please contact us at +1 (307) 317-7213. The cut off time is 4 pm EST.

Lead time is usually 5-10 business days to receive an order after purchase.

We offer free shipping on all orders and applicable items and brands within the mainland of the US (Hawaii, Alaska, and Overseas Territories are exclusions).

Eco Solar Kits does not ship orders directly to Hawaii, Alaska, or Overseas Territories. Clients needing delivery to these locations must arrange a freight forwarder and enter the forwarder’s address as the shipping address. Eco Solar Kits will then ship the order to the designated freight forwarder under our standard shipping terms.

Typically, orders are processed immediately upon receipt, taking approximately 1-4 business days after order confirmation, payment, and pick-up time to fulfill.

The delivery time via freight carrier may vary between 4-6 business days, depending on your location.

  • The minimum order value required for purchase is $69.
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  • Delivery Services We Use Mainly:
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Shipping Concerns:

To prevent delays, frustration, and additional costs, kindly inform us of any concerns regarding the delivery to your location. It's important to note that the following situations may incur additional costs:

  • Charges imposed by the freight company if an 18-wheeler truck cannot access the delivery location
  • Restrictions on truck height or bridge laws during transportation
  • Deliveries to islands
  • Road or access restrictions
  • Delivery requiring the use of a ferry, train, plane, or additional courier transport

Contact Information:

You can reach us using the contact methods provided below:

Return and refund policy

At D&D Eco Power Goods LLC, we strive to ensure our customers are completely satisfied with their purchases. Our return and refund policies are designed to provide a fair and transparent process based on the delivery date of your item.

Return Eligibility

You have 30 days from the delivery date to initiate a return. To be eligible for a return, the item must meet the following conditions:

  • Unused and packaging intact: The item must be in its original packaging and condition.
  • All tags intact: Any tags must remain attached.
  • Proof of purchase: You will need to provide a receipt or proof of purchase.

Items that do not meet these conditions will not be accepted for return.

Circumstances under which returns are offered

  • Canceling an order: You may cancel your order before it has shipped. A 3% deduction will apply to cover platform fees from the total amount paid.
  • Damaged on arrival: If your item arrives damaged, please file the damage with the shipping carrier and contact us within 24 hours of delivery to assess the issue. We may request photos of the damage.
  • Faulty manufacturing or broken after use: Items with manufacturing defects or that break under normal use are covered under the manufacturer's warranty. Please contact us for guidance.
  • Changed your mind: If you decide to return an item because you changed your mind, please ensure it meets the return eligibility criteria stated above. The client will be responsible for the return shipping costs.
  • Exchanges: To expedite an exchange, return the unwanted item first and place a new order for the desired item.
  • Wrong product received: If you receive the wrong item, please contact us immediately so we can rectify the issue.

How to initiate a return

To begin the return process, please follow these steps:

  • Contact us: Reach out via phone at +1 (307) 317-7213, live chat on the website, or email us at hello@ecosolarkits.com. You can also fill out the contact form on our website.
    • Provide necessary information: Your order number
    • First and last name of the person who paid for the order
    • A brief description of the issue
    • Photos of the product (if applicable, especially for damaged items)
  • Return authorization: You will receive a return authorization from our team. Returns without prior authorization will not be accepted.
  • Return shipping instructions: Eco Solar Kits is responsible for return shipping costs if the return is due to a damaged or incorrect item. In such cases, we will provide the customer with a return shipping label to download and print.
  • If our managers are unable to obtain the shipping address and label from the manufacturer within 15 business days, the customer will receive the shipping label directly from us and should send the products to 1309 Coffeen Avenue STE 1200, Sheridan, WY, 82801, USA.

Refund policy

We prioritize customer satisfaction and aim to provide a seamless refund experience. This refund policy is based on the delivery date of your item to ensure fairness in the return process.

Circumstances under which refunds are offered

  1. If the products never arrived: If your order does not arrive within the expected delivery timeframe, please contact us. We will investigate the issue with the carrier and, if confirmed as lost, process a full refund.
  2. Damaged on arrival: If your item arrives damaged, please notify us within 24 hours of delivery. We may ask for photographs of the damage to facilitate the refund process. Once approved, you will receive a full refund.
  3. Faulty manufacturing or broken after use: Items that exhibit manufacturing defects or break under normal use are covered under our warranty. Please reach out to us with details of the issue, including photos. If the item is confirmed faulty, you will be eligible for a full refund or replacement, depending on your preference.
  4. Changed their mind: If you decide to return an item because you changed your mind, it must be returned in its original, unused condition, following the return policy guidelines. Once the return is approved, you will receive a refund, minus any applicable restocking fees.
  5. Wrong product received: If you receive an incorrect item, contact us immediately. We will provide instructions for returning the wrong product, and once received, you will be eligible for a full refund or exchange for the correct item.

When to expect a refund

Refunds will be processed based on the delivery date of the returned product. Once the manufacturer receives and inspects your returned item, we will notify you regarding the approval or rejection of your refund. If approved, the refund will be processed through your original payment method, typically within 10 days. Please note that it may take some time for your bank or credit card company to process and post the refund.

Additional information

  • Return window extension: The return window is extended to 35 days during the following periods:
    • Orders between Nov 25, 2025, and Nov 30, 2025
    • Orders between Dec 25, 2025, and Dec 31, 2025
  • Restocking fee: Returns not related to damaged items may incur a 25% restocking fee.
  • Refund processing time: The processing time for refunds is approximately 10 days from receipt of the returned item.

Contact information

For any questions or concerns regarding our return or refund policy, please do not hesitate to contact us: