SAJ Battery Review 2026: B2, B2S Specs, Price and Verdict

SAJ (Guangzhou Sanjing Electric) is a Chinese inverter maker whose B2 battery is a regular line item on budget solar and battery quotes in Australia. The B2 and the newer B2S are modular, high-voltage lithium iron phosphate (LFP) stacks that bolt onto SAJ’s H2 hybrid inverters, and SAJ also sells all-in-one systems (HS2, and the new HS5). This review is based on manufacturer documentation, warranty terms, published pricing and owner and installer feedback; Solar Cobber did not test the product and was not paid by the manufacturer. Our companion SAJ inverter review covers the hybrid inverters the battery needs.

What it is and how it works

The B2 is a DC battery with no inverter of its own. Each module holds 5.0 kWh nominal (4.8 kWh usable on the Clean Energy Council list), and one to five modules stack into a single tower with a control unit on top. Because it runs at 102 V per module, a full stack sits at about 512 V, so it is a high-voltage battery that connects to a hybrid inverter over DC. Our guide to AC-coupled versus DC-coupled batteries explains what that means for efficiency and retrofits.

The B2S is the upgraded generation. SAJ describes it as supporting 1C charge and discharge, up to 8 stacks in parallel (200 kWh), and the Clean Energy Council lists it from 12.8 to 51.2 kWh in 6.4 kWh steps. The HS2 all-in-one pairs an SAJ hybrid inverter with B2-style modules in one system; SolarQuotes puts it at up to 18 kWh single phase and 22.5 kWh three phase. The HS5 is newer again, with 7 kWh and 9 kWh battery modules, and appeared on the CEC lists on 11 September 2026.

SolarQuotes says SAJ is a budget brand and that the batteries had, at the time it last reviewed them, among the lowest wholesale prices per kWh it had seen. Finn Peacock’s caution is that the low price “makes me nervous”, which is a fair summary of the whole decision.

Specs that matter in Australia

A B2 tower tops out at 24 kWh usable, while B2S reaches 51.2 kWh in one stack, which is bigger than almost any Australian home needs (see what size battery you need).

Power. The Clean Energy Council rates a five-module B2 at 15.36 kW (3.072 kW per module, about 0.64 of its usable kWh) and the B2S at 0.5 kW per kWh (25.6 kW for 51.2 kWh). SAJ’s older B2S datasheet claims 1C, which does not match the listing, so ask your installer which figure the hybrid inverter will actually deliver. In practice the inverter sets the ceiling.

Heat and weather. The B2 datasheet gives charging from 0 to 50 °C and discharging from -10 to 50 °C, and the warranty requires operation between -10 and 50 °C and sufficient ventilation. It is IP65, so it can go outside, but SolarQuotes recommends keeping it out of direct sun and rain. The CEC listing runs to 31 December 2027.

Weight. A B2 module is about 50.5 kg, so a five-module tower is around 250 kg on the datasheet. Ask whether your slab or wall can carry it.

Phases. The battery follows the inverter. SAJ’s H2 hybrids come in single-phase and three-phase versions; see single versus three phase power.

Depth of discharge. SAJ’s Australian page says 90%, the B2 datasheet says 96% and the CEC usable figure (4.8 of 5.0 kWh) matches 96%. Use the CEC figure, because it is what the rebate counts.

Price in Australia

SAJ does not publish retail prices, and the usual independent price lists do not include it. SolarQuotes lists a “SAJ B2 10 kWh” at about A$5,500 (9 kWh usable, 5 kW) without saying whether that includes the inverter, installation or the federal discount. The only itemised price we found is old: Solar4Ever’s March 2024 supply list had a A$890 floor stand and control unit plus A$3,080 per 5 kWh module.

The two Whirlpool figures are as recorded in our SAJ inverter review; we could not reopen the threads in November 2026, and neither poster said whether the figure was before or after the battery discount. Treat the table as a guide to the price tier, not a quote.

The 2024 list does show how cost falls per kWh as modules are added, because the base unit is paid once.

Going from one to two modules cuts the supply price per kWh by about 11%, and the gains flatten after three, so a 10 to 15 kWh stack is the sensible value zone on 2024 pricing.

How the federal discount applies

The Cheaper Home Batteries Program pays small-scale technology certificates (STCs) per usable kWh: 6.8 per kWh from May to December 2026, 5.7 from 1 January 2027, with the first 14 kWh at the full rate, 14 to 28 kWh at 60% and 28 to 50 kWh at 15%. This is consistent with our battery rebate guide and state-by-state rebates. The B2 and B2S are on the approved list, so they qualify when installed with an eligible system.

A 9.6 kWh B2-10.0 earns about A$2,400 now and A$2,000 after the step-down, so installing before 31 December 2026 is worth roughly A$200 to A$1,050 across these sizes. Doubling from B2-10.0 to B2-20.0 does not double the discount, because capacity above 14 kWh earns only 60%.

Warranty: the fine print

SAJ’s Australian battery warranty (V4.0) covers the B1, BU2, B2 and B2S batteries and the AS2 and HS2 systems. The terms that matter:

• Term: 10 years from commissioning, or 10 years and 6 months from shipment, whichever is earlier.
• Retention: 60% of usable capacity, or the minimum throughput, whichever comes first. SolarQuotes’ page says 70% and a drop to 5.5 years if the battery is offline, but we could not find either in V4.0.
• Throughput: 3.06 MWh per usable kWh. SolarQuotes works out the cap is reached just before 8.4 years at one full cycle a day. The warranty lists B2S models under the same figure, although SAJ’s B2S datasheet claims 3.65 MWh per kWh.
• Conditions: faults reported within 30 days, installation within 6 months of shipment, operation between -10 and 50 °C, and only a compatible inverter and battery.
• Remedy: SAJ repairs or replaces at its discretion, may supply a non-new replacement, and says it will cover “approved repair or replacement costs”. It does not itemise installer labour.
• Not covered: moving the battery to a new site without permission, poor ventilation, lightning, grid overvoltage and use of an incompatible inverter.
• Who to call: your installer first. SAJ Digital Energy Australia Pty Ltd is named in the document, and SolarQuotes lists a Melbourne (Tullamarine) office and 1800 888 725.

The newer HS5 terms (v1.0, 8 August 2026) are more generous.

SAJ’s B2 and B2S warranty has the lowest throughput allowance of the products charted: 3.06 MWh per kWh equals about 3,060 full cycles, or 8.4 years at one a day. The HS5 EK90 (15 years, 70% retention, 4.4 MWh per kWh) is the exception, but it needs an internet connection to keep the full term and is only warranted as a complete SAJ system.

What owners and installers report

SolarQuotes shows 4.4 out of 5 from 27 SAJ battery ratings as at 14 November 2026. The ratings are mostly positive, with a long tail of single low scores.

Seven in ten reviewers (19 of 27) gave five stars; 2 gave one or two. That is a small sample from an installer-referral site, so treat it as a sentiment check, not a reliability measure.

Praise. Reviewers describe a stylish, simple install, an easy Wi-Fi interface and good value. SolarQuotes lists budget pricing and an easy-to-use app as the pros.

Complaints. The patterns are:

• Support and software. Owners on SolarQuotes and Whirlpool describe slow replies, time-of-use settings that did not behave as expected and firmware problems (see our inverter review for detail).
• Automation. One Victorian reviewer in November 2024 was still waiting for Evergen or Amber to optimise the battery. We could not confirm which VPPs formally support SAJ; read what a VPP is and ask your installer.
• Warranty reach. SolarQuotes’ conclusion is that the warranty “may not be sufficient” for batteries used at a high capacity factor.

No SAJ product appeared on the Clean Energy Council’s product recalls page when we checked on 14 November 2026.

SAJ B2 vs alternatives

Choose the SAJ B2 if price is the priority and your installer will back it with local support. The Sungrow SBR has a far larger Australian installed base and unlimited-cycle cover for home use. The Alpha ESS SMILE-G3 is an all-in-one with a similar throughput cap and a rival price tier. The Fox ESS EQ4800 offers about 38% more throughput per kWh than SAJ’s B2 and a 70% retention promise.

Questions to ask your installer

• Which exact model is this (B2, B2S or HS5), with the CEC certificate number, and does it match the one listed on my install date?
• Is the quote before or after the federal discount, and how many STCs does it assume for my usable kWh?
• Which warranty applies: V4.0 (60%, 3.06 MWh per kWh) or an HS5 version?
• Will you register the system and keep it online, and does SAJ require that for the full term?
• Who pays labour if SAJ replaces a module, and what is your own workmanship warranty?
• Which VPPs or dynamic tariffs has this battery and inverter been approved for in my network area?
• Where will it be mounted, and can the wall or floor carry about 250 kg for a five-module stack?
• What happens to support if your business closes?

FAQ

Is the SAJ B2 battery any good?

It is a competitive budget battery with a large capacity range and a CEC listing to 31 December 2027, but its warranty is throughput-capped and owners report patchy support. SolarQuotes owners rate it 4.4 out of 5 from 27 ratings.

Is the SAJ battery approved in Australia?

Yes, the B2 (BAT-937) and B2S (BAT-902) are on the Clean Energy Council approved batteries list with expiry on 31 December 2027, as checked on 14 November 2026. We found no HS2 entry, so confirm any HS2 quote.

How much does an SAJ battery cost?

SAJ publishes no retail price. SolarQuotes lists a 10 kWh B2 at about A$5,500, and owner quotes of about A$8,100 to A$8,900 installed with an H2 inverter and 18 to 20 kWh were reported in 2025. Get a current quote that states whether the federal discount is included.

How long is the SAJ battery warranty?

The B2 and B2S carry 10 years, 60% retained capacity, or 3.06 MWh per usable kWh, whichever comes first, under the Australian V4.0 warranty. The HS5 EK90 system is warranted for 15 years and the EK70 for 10 years (v1.0, August 2026).

Which inverter works with the SAJ B2 battery?

SAJ’s H2 hybrid inverters are the standard pairing, and the warranty excludes an incompatible inverter. Some third-party battery inverters can work, but check approval in writing.

What is the difference between the SAJ B2 and B2S?

The B2S is the newer generation, listed in larger 6.4 kWh steps up to 51.2 kWh, while the B2 is 4.8 kWh modules up to 24 kWh. SAJ’s own documents disagree on the B2S power and throughput figures, so ask for the current datasheet.

Does the SAJ battery qualify for the federal battery discount?

Yes, B2 and B2S installs can earn STCs under the Cheaper Home Batteries Program at 6.8 per usable kWh until 31 December 2026 and 5.7 from 1 January 2027. A 9.6 kWh B2-10.0 earns roughly A$2,400 at an assumed A$37 per STC.

Find an installer

With a budget brand, your installer’s support matters as much as the hardware, because a warranty claim starts with them. Use our installer directory to find SAJ installers near you, check how to compare solar quotes before you sign, and read how long solar batteries last for the throughput maths.

A short manufacturer video shows how SAJ’s modular stack goes together.

The video above, from SAJ Electric’s own channel, is an installation guide for the three-phase HS2 all-in-one that uses the same modular approach; it is manufacturer content, not an independent test.