SAJ AS1-3KS-5.1 – AC retrofit battery system 3 kW with 5.1 kWh storage

The SAJ AS1-3KS-5.1 turns an existing solar panel installation into a full-fledged home battery system in one fell swoop. The AS1 is an AC retrofit solution with a 3 kW single-phase inverter and an integrated 5.1 kWh lithium battery, which you simply place next to your current PV inverter. So you do not need to replace an inverter: the AS1 simply hangs as an additional “energy block” in your meter box or technical room. :contentReference[oaicite:1]{index=1}

The battery capacity is also expandable up to 20.4 kWh with additional SAJ B1-5.1-48 modules (up to 3 additional B1s in addition to the internal 5.1 kWh). So your system grows with you if you later get a heat pump, electric car or dynamic contract. :contentReference[oaicite:2]{index=2}

Key advantages of the SAJ AS1-3KS-5.1

• All-in-one retrofit – 3 kW AC-coupled inverter with integrated 5.1 kWh battery in one housing.
• Compatible with all PV inverters – operates AC-coupled, so suitable with almost all brands and types of existing inverters. :contentReference[oaicite:3]{index=3}
• Expandable up to 20.4 kWh – with up to three additional B1-5.1-48 battery modules (AS1 + 3× B1). :contentReference[oaicite:4]{index=4}
• UPS function – emergency power possible; switches over on mains failure in ≤ 10 ms so that critical devices keep running. :contentReference[oaicite:5]{index=5}
• Low-voltage battery 48 V – safe Li-ion battery with 51.2 V rated voltage and integrated BMS. :contentReference[oaicite:6]{index=6}
• IP65 & quiet operation – splash-proof housing with natural cooling and noise level < 29 dB(A), so pleasant in the house. :contentReference[oaicite:7]{index=7}
• Monitoring & energy management – via the SAJ app and portal, you have insight into PV, battery and consumption.

Application – when to choose the AS1-3KS-5.1?

• You already have a working grid-connected PV system and want to add a home battery without an inverter swap.
• You want a single-phase 3 kW battery inverter with a 5.1 kWh starter package that can be expanded later.
• You are looking for a system with UPS/emergency power function for a number of groups (fridge, router, lighting etc.).
• You want to operate AC-connected, so that in case of a future inverter upgrade, you don’t have to convert your entire battery system.

Technical specifications SAJ AS1-3KS-5.1

Battery parameters

• Battery type: lithium-ion (48 V platform)
• Total energy: 5,120 Wh
• Battery capacity: 100 Ah
• Rated voltage: 51.2 V
• Voltage range: 42 – 58.4 V
• Depth of Discharge (DoD): ≤ 90%
• Cycle life: ≥ 6,000 cycles at rated conditions
• Max. charge current: 60 A
• Max. discharge current: 60 A
• Scalability: expandable up to 20.4 kWh (AS1 + 3× B1-5.1-48)

AC side (grid & back-up)

• Rated mains voltage: 220 / 230 / 240 V AC, 1-phase, L+N+PE
• Rated output power: 3,000 VA
• Max. output current: 13.1 A @ 230 V
• Mains frequency: 50 / 60 Hz (range ± 5 Hz)
• Power factor: adjustable from 0.8 leading to 0.8 trailing
• UPS function: switchover time ≤ 10 ms (back-up mode)

General data

• Cooling: natural convection (fanless design)
• Noise level: < 29 dB(A)
• Protection rating: IP65
• Operating temperature: approx. -5 °C to +50 °C
• Relative humidity: 0 – 95 % (non-condensing)
• Dimensions (h × w × d): 738 × 650 × 186 mm
• Weight: approx. 64 kg
• Communication: including Ethernet and WiFi
• Standard warranty: 5 years (some suppliers offer 10 years via extension). :contentReference[oaicite:8]{index=8}

Compatibility and extension with B1 batteries

• Works AC-coupled with all common grid-connected PV inverters (1-phase and 3-phase), as it hangs on the AC side in the system. :contentReference[oaicite:9]{index=9}
• Expandable with SAJ B1-5.1-48 battery modules (in parallel with the internal battery), up to a maximum of 3 additional B1s.
• With 1, 2 or 3 additional B1 modules, you get to 10.2 / 15.3 / 20.4 kWh total storage capacity, respectively. :contentReference[oaicite:10]{index=10}

Installation tips for do-it-yourselfers and installers

• 1. Location & suspension
  The AS1-3KS-5.1 weighs about 64 kg; so choose a solid bearing wall (concrete, sand-lime brick, solid brick). Mount the accompanying suspension plate level before hanging the unit. :contentReference[oaicite:11]{index=11}
• 2. Indoors or sheltered outdoors
  Thanks to IP65, the unit may be hung in the garage, shed or under a shelter. Avoid direct sunlight and provide enough space around for cooling (keep top and sides clear).
• 3. AC retrofit on existing PV
  Connect the AS1 with its own group to the meter cupboard. The existing PV inverter continues to do what it does; the AS1 measures the direction of current via the supplied CTs or meter and charges/discharges the battery if convenient.
• 4. Schedule backup outputs
  If you really want to make use of the UPS function, plan a separate backup group or small emergency distributor. Connect only critical consumers to this (fridge, wifi, lights, server/NAS).
• 5. Expansion with B1 modules
  When first mounting on the wall, leave room for 1-3 additional B1-5.1-48 modules in addition to the AS1. Cabling and mounting plates are clearly described in the manual.
• 6. Mains connection by authorised installer
  You can do most of the hanging and preliminary work yourself, but the mains connection, protection and commissioning should always be carried out or checked by a competent installer.

SAJ AS1-3KS-5.1 Buy from Radiant Green

With the SAJ AS1-3KS-5.1, you give an existing solar panel system a major upgrade: you go from “feed everything back” to smart storage and consumption, with emergency power option and expandable capacity.

We will be happy to help you complete the set: from additional B1 battery modules to the right cabling, group in the meter box and practical tips for installation. Feel free to send us a picture of your meter box and existing inverter, and we will help you find out whether this is the right retrofit solution for your situation.

Datasheet Manual