Product Overview
Eltek Theia 48V Sine Wave Inverter — DC/AC Power for Off-Grid Telecom Sites
Eltek Theia 48V sine wave inverters convert a -48 V DC plant into clean 230 VAC single-phase power for sites where the battery is the heart of the system. They are built for off-grid telecom stations, solar-hybrid sites and outdoor cabinets that need to run AC loads — routers, transmission gear, monitoring equipment, small tools — from the same 48V battery string that feeds the DC load bus.
The platform is based on the Eltek INV222-class DC/AC module: 48 VDC input (40.8–67.5 VDC operating window), 230 VAC ±0.5% pure sine output, efficiency ≥90%, and CAN-bus control. Modules are hot-pluggable in 19-inch subracks (up to 4 modules in 2U) and can run in parallel with redundant synchronization — up to 10 modules per AC group — so capacity grows from 0.7 kVA single modules to 3 kVA-class systems without changing architecture.
BS Comtec supplies Eltek Theia-class 48V sine wave inverters across four capacity classes — 0.7 kVA, 1.3 kVA, 2.2 kVA and 3 kVA — with OEM configuration, factory-direct pricing and worldwide delivery for telecom, solar EPC and industrial customers in Europe, Latin America, the Middle East, Africa and Russia.
Key Features
- Pure sine wave 230 VAC output (±0.5% static regulation), suitable for sensitive IT and telecom loads
- 48 VDC input with wide 40.8–67.5 VDC window — works directly on a -48 V battery plant
- Efficiency ≥90% with temperature-controlled fan cooling
- CAN-bus interface; parallel operation up to 10 modules with redundant synchronization bus
- 130% overload capability for 10 seconds — handles motor and inrush starts
- Hot-plug design with backplane connection; 4 modules in 2U of 19-inch rack
- Input under/over-voltage, overload and continuous short-circuit protection
- Optional three-phase operation and STS (static transfer switch) integration
Specifications (INV222-class 48VDC→230VAC platform)
| Parameter | Value |
|---|---|
| DC input voltage | 48 VDC nominal, 40.8–67.5 VDC range |
| AC output | 230 VAC ±0.5% (adjustable 200–242 VAC), 50 Hz ±0.01 Hz |
| Capacity classes | 0.7 kVA / 1.3 kVA / 2.2 kVA / 3 kVA (parallel scalable) |
| Efficiency | ≥90% overall |
| Overload | 130% for 10 s; continuous short-circuit proof |
| Output quality | THD ≤2% at linear load; power factor range 0.5 ind. – 1 – 0.5 cap. |
| Parallel operation | Up to 10 modules, current sharing ≤10%, no master module |
| Communications | CAN-bus; relay alarm contact; external synchronization via STS |
| Mechanical | 106.4 × 88.4 × 335 mm (1/4 × 19″, 2U), approx. 3.5 kg per module |
| Ambient | -20 to +55 °C (2%/K derating above +40 °C) |
| Connections | DIN41612-M backplane connectors, hot-pluggable |
Capacity Selection Guide
| Capacity class | Typical AC load | Battery draw @ 53.5 V (approx.) | Typical site |
|---|---|---|---|
| 0.7 kVA | Router, ONU/OLT shelf, CCTV, small monitoring | ~14 A | Outdoor cabinet, roadside node, FTTx POP |
| 1.3 kVA | Small BTS + transmission + monitoring | ~26 A | Rooftop or pole site with 48V plant |
| 2.2 kVA | Macro-site single cabinet AC load, industrial controller | ~43 A | Off-grid base station, pipeline RTU |
| 3 kVA | Multi-equipment shelter, small shelter AC bus | ~59 A | Solar-hybrid shelter, mining or border site |
Sizing rule of thumb: list every AC load, add starting surge (motors and compressors can draw 3× rated current), keep continuous load ≤80% of the inverter class, then verify the 48V battery can deliver the DC-side current for the required backup time. For a 3 kVA class at full load, budget roughly 59 A from the -48 V string.
Theia Inverter vs Eltek Rectiverter — Where the Line Sits
Both families connect the 48V battery world with 230 VAC, but they answer different questions. The Theia/INV inverter line is a one-direction DC→AC converter: it takes energy from an existing -48 V plant and feeds AC loads. The Rectiverter is a three-port device — rectifier, inverter and transfer switch in one box — that charges the battery from AC mains, feeds DC loads and backs up AC loads at the same time (for example 230/1500 48/1200: 1500 VA AC plus 1200 W DC from a single 1U module).
| You need | Choose |
|---|---|
| AC output only, battery already charged by an existing rectifier plant or solar MPPT | Theia 48V sine wave inverter |
| AC backup + 48V rectifier charging + DC distribution in one compact unit | Eltek Rectiverter (see Rectiverter 6kVA system) |
| Bidirectional AC↔DC energy flow for storage integration | CE+T Sierra 25 class (Sierra 25 3kVA) |
Solar Off-Grid and Hybrid Site Architecture
The typical off-grid chain looks like this: PV strings feed a 48V solar MPPT charge stage (such as the Eltek Flatpack2 48/3200 HE Solar), the MPPT output keeps the -48 V battery bank charged, DC loads hang directly on the 48V bus, and the Theia inverter adds a 230 VAC bus for the AC loads — monitoring, tools, lighting, small climate devices. Because the inverter rides on the battery, PV fluctuation never reaches the AC output. For complete reference designs — battery sizing, MPPT count and load budgets for African and Middle East sites — see our Off-Grid Solar Hybrid Telecom Power reference.
BS Comtec delivers the full chain factory-direct: solar MPPT modules, -48 V rectifier plants, battery distribution, the Theia-class inverter and the monitoring layer — configured as one system, shipped worldwide from a single supplier.
Key Features of Eltek Theia 48V Sine Wave Inverter
The Eltek Theia 48V sine wave inverter family is part of the 48 V DC power ecosystem used across telecom and off-grid industries. Systems in this class combine rectifier modules, solar MPPT chargers, monitoring controllers and DC/AC inverters on a single -48 V bus, which keeps installation, spares and monitoring uniform across sites.
Typical Applications of Theia 48V Inverters
Typical deployments include off-grid telecom base stations, solar-hybrid shelters, outdoor battery cabinets needing an AC service outlet, railway and pipeline monitoring points, and rural FTTx POPs. Wherever a -48 V battery plant exists but one or more loads need genuine 230 VAC, a 0.7–3 kVA sine wave inverter is the shortest path.
Selecting a 48V Sine Wave Inverter with BS Comtec
BS Comtec supplies Eltek Theia-class inverters, Rectiverter systems and matching 48V plants with OEM configuration and global delivery. Send us your AC load list, backup-time target and battery configuration, and we will return a sized proposal with lead time and factory pricing.
Frequently Asked Questions
What is the difference between an Eltek Theia inverter and an Eltek Rectiverter?
A Theia-class inverter is a one-direction DC/AC converter: it turns your existing -48 V battery energy into 230 VAC. A Rectiverter is a three-port unit that rectifies AC mains to charge the 48V battery, feeds DC loads, and inverts to AC during outages — all in one module. Choose the inverter when a rectifier plant already exists; choose the Rectiverter when you need AC backup and rectification in a single compact box.
How do I size a 48V sine wave inverter for an off-grid site?
Sum the continuous watts of all AC loads, apply starting-surge factors (inductive loads can draw 3× nameplate), keep the total at or below 80% of the inverter capacity class, and check that the 48 V battery can supply the DC-side current — roughly kVA × 1000 ÷ 53.5 V — for the whole required backup time. If surge-driven sizing pushes you between classes, take the larger class or parallel two modules.
Can Theia inverters run in parallel on my existing 48V plant?
Yes. The INV222-class platform connects over CAN-bus and supports parallel operation of up to 10 modules with automatic current sharing (≤10% deviation) and a redundant synchronization bus — no master module needed. Modules are hot-pluggable, so capacity can be added during operation, and an STS can be added for higher-availability two-source architectures.
Eltek Theia Inverter in Hybrid and Solar Off-Grid Architectures
The Eltek Theia inverter family is the natural AC layer on top of an existing 48V DC plant: rectifiers charge the battery and feed DC loads, while Theia modules regenerate a 230 V pure sine AC bus for equipment that cannot run on DC — monitoring servers, routers with internal AC supplies, climate controllers and small workshop tools. In solar off-grid and bad-grid sites across Africa, the Middle East and South America, the same 48V bus is commonly shared between PV charge controllers, Eltek rectifiers and Theia inverters, so one battery string serves all three sources. Because Theia modules parallel over CAN-bus (up to 10 per bus), the AC capacity grows in small steps instead of forcing an oversized single unit — the same building-block logic BS Comtec applies when dimensioning the DC side of the site. When you compare a dedicated Eltek Theia inverter against a conventional monolithic UPS for such sites, the deciding factors are usually battery-sharing, step-wise growth and the wide 40.8–67.5 V DC input window.
Q: What is an Eltek Theia inverter used for?
An Eltek Theia inverter converts the 48V DC bus of a telecom power plant or battery bank into a 230V AC pure sine output, so AC-rated equipment — servers, network gear, meters, small climate units — can run from the same batteries that back the DC loads. Typical placements are off-grid and bad-grid telecom sites, solar hybrid cabinets, and small technical rooms where one 48V plant powers everything.
Q: Which Eltek Theia inverter capacity should I choose — 0.7, 1.3, 2.2 or 3 kVA?
Add the continuous watts of all AC loads, multiply inductive loads by their starting-surge factor, and keep the total at or below 80% of the frame rating. A single 0.7–1.3 kVA module covers monitoring and network racks; 2.2–3 kVA handles small climate or workshop loads. If your load sits between two frames or must grow later, start with one module and parallel a second over CAN-bus rather than oversizing upfront.
Q: Can an Eltek Theia inverter share batteries with my rectifier plant?
Yes — this is the standard architecture. Theia modules connect to the same 48V bus as the Eltek Flatpack2 rectifiers and the battery string, with the 40.8–67.5 V DC input window matching the float and equalize voltages of typical VRLA and lithium plants. Set the inverter’s low-voltage disconnect above the battery protection threshold so AC loads disconnect before the DC plant is endangered, and one battery string backs both the AC and DC sides. BS Comtec sizes the combined DC/AC layout as part of the RFQ.
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