Set up split-phase grids – easier than ever

The Smartformer is the complete solution for off-grid and backup plants of up to seven kilowatts. At the same time, it acts as a AC distributor and a 120/240-volt autotransformer. The transformer provides step-up and step-down options to supply loads with 120 V and 240 V using a Sunny Island and a Sunny Boy – with a high level of efficiency over the entire power spectrum. Thanks to the pre-wired bypass function, the PV plant can be bridged without problems via a robust switch for maintenance work. The optimized transformer overload protection and a load-shedding contactor provide extra protection to the system. The Smartformer makes the stand-alone power supply simple and reliable.


  • Pre-wired AC distribution board
  • Quick installation and commissioning
  • Suitable for SI 4548 / 6048-US


  • Bypass switch for direct grid operation
  • Load-shedding contactor to prevent battery deep discharge
  • Miniature circuit-breaker for PV and load


  • Max. efficiency: 99 percent
  • Highest yield in the entire power range


  • UL listed
  • Optimized overload protection
  • Warranty: 5 years as standard – extendable to 20 years

Data sheet

SMARTFORMER FOR SUNNY ISLAND - Split-phase stand-alone grids - now easier than ever SMARTFORMER-DUS124616W.pdf
  • Type: Data sheet
  • Language: English (US)
  • Number: SMARTFORMER-DUS124616
  • Version: 1.6

Technical Description

SMARTFORMER FOR SUNNY ISLAND - Technical description / Descripción técnica SI_TDBOX-US-TB-en_es-12.pdf
  • Type: Technical Description
  • Language: International
  • Number: SI_TDBOX-US-TB-en_es-12
  • Version: 1.2

Installation Guide

SMARTFORMER FOR SUNNY ISLAND - Installation Manual SI_TDBOX-IA-eng-IUS122211.pdf
  • Type: Installation Guide
  • Language: English (US)
  • Number: SI_TDBOX-IA-eng-IUS122211
  • Version: 1.1


Certificate of Compliance - SMARTFORMER FOR SUNNY ISLAND SI-TD-BOX-10-ZE-CoC-UL-en-10.pdf
  • Type: Certificate
  • Language: English (US)
  • Number: SI-TD-BOX-10-ZE-CoC-UL-en-10
  • Version: 1.0

Off-grid solutions from SMA

Our modular concepts provide the ideal technical off-grid solution for a wide range of capacities and all relevant plant types.

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Learn more about the flexible uses of our products by seeing how they are used at selected reference plants.

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