Solar Batteries
Updated August 2024
Series-connected, modular batteries.(Type 1)
e.g...Sungrow SBR/SBH (3.2kWh/5kWh modules), BYD HVM (2.76kWh modules), Goodwe F-G2 (3.2kWh modules).
Typically there is a BMS/DC-DC controller costing $1200-$1600 on top of the stack.
The stack is made up of usually 2 to 10 modules with LFP cells, at a cost of $670-$850 per kWh.
So, a typical 10kWh battery costs between $6,700 and $8,500 plus the BMS.
I'd like to say that there is a good reason for why one is more expensive than the other,
but there's really nothing different with Type 1 batteries, apart from brand recognition.
Parallel-connected, modular batteries with battery optimisers. (Type 2)
e.g...iStore (made by Huawei, 5kWh modules), Sigenergy (5kWh and 8kWh modules).
Also LFP cells but with quite a bit more technology designed to extend the life and output.
By including an optimiser and parallel connecting each module the batteries work independently.
This allows cell balancing, charging and discharging to be done per battery, not per stack.
Both these brands also include fire extinguishers which are nice to have but don't add to the performance.
BMS/Power control unit for iStore/Huawei is $1,200 with battery costs (inc optimisers), $790 per kWh.
Sigenergy build the power control, BMS into their inverter so you just buy the battery at $750/kWh
(Note Sigenergy is a brand new product and is discounted at the moment to gain market attention).
Monolithic batteries. (Type 3)
These aren't buildable 'stacks', they are larger one-size single battery packs.
e.g...Tesla Powerwall 2 (13.5kWh), SolarEdge Energy Bank (10kWh), Alpha ESS (10 or 13kWh)
The Tesla PW2 contains a battery charger and 5kW battery inverter and is used for 'AC coupling'.
AC Coupling means it can be added to any home, any solar, in fact even homes without any solar.
Along with a second 'Gateway box' this costs $860 per kWh.
Sadly this excellent product has ceased production, superseded by the Powerwall 3 (PW3).
It currently looks like PW3 may have problems being approved for use In Western Australia.
It is a wait and see situation at the moment.
The SolarEdge battery costs $1,160/kWh, the Alpha ESS just $715/kWh.
The biggest downside of monolithic batteries is when you want 'a bit more' or 'a bit less'.
One size fits all, so you can't finesse the exact size that suits your home consumption.
Modular batteries have the edge there.
Which is best?
I favour the second type, parallel connected batteries with optimisers.
The optimisers and parallel connection should add many years to the useful output of the batteries.
You can also add new batteries to old later on without losing any power from the new battery.
There's an important caveat to that last statement...see next.
For series-connected batteries, Sungrow and Goodwe are good.
The best monolithic battery was Tesla Powerwall 2. PW3 is a very different product.
What happens in years to come when I want to add more batteries?
Let's say you installed a 9.6kWh stack of type 1, Sungrow SBR batteries in 2021.
In 2028 you decide you need to add another 9.6kWh giving you a 19.2kWh stack.
"Sorry, but Sungrow ceased production on that last year and there are none left",future you is told.
"The new Sungrow batteries aren't compatible with your existing batteries."
And that's the reality. Unless your retailer/installer forewarns you of an upcoming redundancy,
or you hear of it on the grapevine, your only hope is to belatedly find some second-hand Sungrow SBRs. Unlikely.
I'm not picking on Sungrow as the same applies to people who now want to add a second Tesla Powerwall 2.
Or when iStore bring out their 7kWh modules in 2025/2026, for those people who bought the current 5kWh modules.
Every single product has the same problem, except one.
There is only one company that has really thought this through and designed their product with exactly this problem in mind.
That is new entrant Sigenergy. I'm not blowing their horn trying to sell them, I'm calling it as it is.
All their inverters and batteries are the same physical size.
All their batteries are optimised and parallel-connected, so today's 5kWh and 8kWh modules can be mixed.
In years to come when they release 10kWh and 12kWh and even larger modules, they can be mixed in as well.
The simple genius was to design everything the same size.
Yes, it's ridiculous that their 5kW single phase inverter is the same size as their 30kW three phase model.
It makes it nearly twice as large as a normal 5kW 1ph inverter, but it makes it future-proofed,
because the same-size battery cases fit under the same-sized inverters.
Aren't batteries meant to be too expensive?
You can pay back the investment from savings on any of the above batteries in 5-6 years.
The batteries, especially type 2 batteries, should give you at least 15 years useful life.
Yes, batteries ARE expensive, but you can still make them pay for themselves.
In WA we have no feed in tariff payments for inverters greater than 5kW.
Even for smaller 5kW inverters you only get paid 2 cents per kWh for surplus solar power sent back into the grid.
If you are on the Midday Saver Synergy tariff your peak rate of power, 3pm to 9pm is currently 52 cents.
You can pay off a battery pretty fast if it's saving you 52 cents per kWh !!
Backup power during grid outages
The most popular battery feature apart from being grid-independent, is backup.
Pick some essential outlet and lighting circuits to work during a blackout.
Larger 3 phase hybrid inverters with batteries can provide 'whole of house' backup.
More marketing spin than reality though.
Why would you drain your battery keeping your oven, pool pump or ducted AC alive in a blackout?
Battery warranties.
As mentioned before, a well managed LFP battery, with excellent cell balancing should last 15-20 years.
There's one brand coming in 2025/2026 that promises a 12,000 cycle warranty. 32 years at one cycle per day.
As you would expect the manufacturers are usually ultra-conservative with their warranties.
They really don't want to give you a new battery in ten years time because they let marketing offer too generous a warranty.
So 10 years warranty to 60% or 70% of original output is typical, but the best batteries are a LOT better than that.
Brochure/Datasheets on some of the batteries we install.
Sungrow SBR
Goodwe Home Lynx F G2
iStore/Huawei
Sigenergy
Alpha ESS B5-13
BYD HVM
SAJ B2
Growatt Ark-XH
SolaX T-Bat
SolarEdge Energy Hub
Installation costs.
Installation costs for the battery, consumption meter and backup with a changeover switch are typically $2,000 for all.
The inverter consumption meter is typically $200 for single phase and $400 for three phase.
Sungrow, SAJ, Goodwe (3 phase only) hybrid inverters include the consumption meter.
Backup components (power from the battery & solar during a blackout) is included with Goodwe, Sungrow, SolaX, SAJ and Alpha.
The other brands have a separate backup box costing...priced below as Single phase/Three phase backup box.
Growatt $330/N/A, iStore $790/$1,200, Fronius/BYD $925/$1,475, SolarEdge $515/N/A
Inverters compatible with these batteries.
A few years ago there were very few 'hybrid' inverters, and they used third party batteries like BYD, Pylontech and LG.
Once demand ramped up, the inverter manufacturers started making their own batteries.
So from the list of batteries above here's what works with what...
I've used the format single phase/three phase below...
Goodwe battery - Goodwe EH (5kW)/Goodwe ET (5-30kW) inverters.
Alpha battery - Alpha (5kW) / N/A inverters.
SAJ battery - SAJ H2-V2 (5-10kW)/SAJ H2-T2 (5-10kW) inverters.
Sigenergy batteries- All Sigenergy inverters.
Growatt battery - Growatt MIN-XH, MIN-XA (5kW)/MOD-XH (5-10kW) inverters.
Sungrow battery - Sungrow SH.RS (5-10kW)/SH.RT (5-10kW) inverters.
SolaX T-Batt battery - Solax X1 (5-7.5kW)/X3 (5-15kW) inverters.
SolarEdge battery - SolarEdge Home Hub/Genesis (5-10kW)/ N/A inverters.
BYD HVM battery - Fronius Primo GEN24Plus (5-10kW)/Fronius Symo GEN24Plus (5-10kW) inverters.
(BYD HVM also works with Goodwe and Sungrow single and three phase hybrid inverters above).
iStore battery - iStore And Huawei (5kW-6kW)/ iStore and Huawei (5kW-6kW) inverters.
Other batteries.
There are many other batteries than those listed above...Dyness, Sofar, Solplanet etc etc.
We recently lost one brand, Redback, who have gone into liquidation, but hopefully will re-emerge.
They were an Australian company, and it's never good to see one of our own fail.
But, how all these manufacturers make enough sales/profits to stick around here is beyond me.
What if the price of lithium battery cells fell 50%?
They have. In fact the price of LFP cells is about 80% lower than 18 months ago.
This has resulted in an average 20% fall in the price of most batteries over that time.
Some have been slower than others for the cost savings to flow through which might be an inventory thing.
A 20% fall in price for the complete battery unit following an 80% fall in the price of cells.
That goes to show that the lithium cell cost is significant in the total cost, but not overwhelmingly so.
AC or DC Coupled batteries
AC Coupled batteries don't connect to a solar inverter, DC Coupled do.
DC coupled inverters are called 'hybrids' because they manage both solar and a battery.
Most of the big inverter brands include some hybrid models in their range.
AC Coupled batteries are an option for people who already have an existing solar installation.
Often times however, it's cheaper and better to chuck out the old solar inverter and replace with a hybrid.
Now that the best AC Coupled battery/inverter, Tesla Powerwall 2 is out of production, choices are limited.
The new Tesla, the Powerwall 3 isn't a battery inverter, it's a hybrid, and that makes it ineligible for AC coupling in WA.
There aren't too many other quality options for 'battery inverter' AC Coupled solutions for WA and our unique rules.
iStore/Huawei 10kWh battery
Fronius GEN24+ inverter & 16.5kWh BYD battery
This review was written by Andrew MacKeith, Solar4Ever service manager since 2011.
Updated August 2024
Series-connected, modular batteries.(Type 1)
e.g...Sungrow SBR/SBH (3.2kWh/5kWh modules), BYD HVM (2.76kWh modules), Goodwe F-G2 (3.2kWh modules).
Typically there is a BMS/DC-DC controller costing $1200-$1600 on top of the stack.
The stack is made up of usually 2 to 10 modules with LFP cells, at a cost of $670-$850 per kWh.
So, a typical 10kWh battery costs between $6,700 and $8,500 plus the BMS.
I'd like to say that there is a good reason for why one is more expensive than the other,
but there's really nothing different with Type 1 batteries, apart from brand recognition.
Parallel-connected, modular batteries with battery optimisers. (Type 2)
e.g...iStore (made by Huawei, 5kWh modules), Sigenergy (5kWh and 8kWh modules).
Also LFP cells but with quite a bit more technology designed to extend the life and output.
By including an optimiser and parallel connecting each module the batteries work independently.
This allows cell balancing, charging and discharging to be done per battery, not per stack.
Both these brands also include fire extinguishers which are nice to have but don't add to the performance.
BMS/Power control unit for iStore/Huawei is $1,200 with battery costs (inc optimisers), $790 per kWh.
Sigenergy build the power control, BMS into their inverter so you just buy the battery at $750/kWh
(Note Sigenergy is a brand new product and is discounted at the moment to gain market attention).
Monolithic batteries. (Type 3)
These aren't buildable 'stacks', they are larger one-size single battery packs.
e.g...Tesla Powerwall 2 (13.5kWh), SolarEdge Energy Bank (10kWh), Alpha ESS (10 or 13kWh)
The Tesla PW2 contains a battery charger and 5kW battery inverter and is used for 'AC coupling'.
AC Coupling means it can be added to any home, any solar, in fact even homes without any solar.
Along with a second 'Gateway box' this costs $860 per kWh.
Sadly this excellent product has ceased production, superseded by the Powerwall 3 (PW3).
It currently looks like PW3 may have problems being approved for use In Western Australia.
It is a wait and see situation at the moment.
The SolarEdge battery costs $1,160/kWh, the Alpha ESS just $715/kWh.
The biggest downside of monolithic batteries is when you want 'a bit more' or 'a bit less'.
One size fits all, so you can't finesse the exact size that suits your home consumption.
Modular batteries have the edge there.
Which is best?
I favour the second type, parallel connected batteries with optimisers.
The optimisers and parallel connection should add many years to the useful output of the batteries.
You can also add new batteries to old later on without losing any power from the new battery.
There's an important caveat to that last statement...see next.
For series-connected batteries, Sungrow and Goodwe are good.
The best monolithic battery was Tesla Powerwall 2. PW3 is a very different product.
What happens in years to come when I want to add more batteries?
Let's say you installed a 9.6kWh stack of type 1, Sungrow SBR batteries in 2021.
In 2028 you decide you need to add another 9.6kWh giving you a 19.2kWh stack.
"Sorry, but Sungrow ceased production on that last year and there are none left",future you is told.
"The new Sungrow batteries aren't compatible with your existing batteries."
And that's the reality. Unless your retailer/installer forewarns you of an upcoming redundancy,
or you hear of it on the grapevine, your only hope is to belatedly find some second-hand Sungrow SBRs. Unlikely.
I'm not picking on Sungrow as the same applies to people who now want to add a second Tesla Powerwall 2.
Or when iStore bring out their 7kWh modules in 2025/2026, for those people who bought the current 5kWh modules.
Every single product has the same problem, except one.
There is only one company that has really thought this through and designed their product with exactly this problem in mind.
That is new entrant Sigenergy. I'm not blowing their horn trying to sell them, I'm calling it as it is.
All their inverters and batteries are the same physical size.
All their batteries are optimised and parallel-connected, so today's 5kWh and 8kWh modules can be mixed.
In years to come when they release 10kWh and 12kWh and even larger modules, they can be mixed in as well.
The simple genius was to design everything the same size.
Yes, it's ridiculous that their 5kW single phase inverter is the same size as their 30kW three phase model.
It makes it nearly twice as large as a normal 5kW 1ph inverter, but it makes it future-proofed,
because the same-size battery cases fit under the same-sized inverters.
Aren't batteries meant to be too expensive?
You can pay back the investment from savings on any of the above batteries in 5-6 years.
The batteries, especially type 2 batteries, should give you at least 15 years useful life.
Yes, batteries ARE expensive, but you can still make them pay for themselves.
In WA we have no feed in tariff payments for inverters greater than 5kW.
Even for smaller 5kW inverters you only get paid 2 cents per kWh for surplus solar power sent back into the grid.
If you are on the Midday Saver Synergy tariff your peak rate of power, 3pm to 9pm is currently 52 cents.
You can pay off a battery pretty fast if it's saving you 52 cents per kWh !!
Backup power during grid outages
The most popular battery feature apart from being grid-independent, is backup.
Pick some essential outlet and lighting circuits to work during a blackout.
Larger 3 phase hybrid inverters with batteries can provide 'whole of house' backup.
More marketing spin than reality though.
Why would you drain your battery keeping your oven, pool pump or ducted AC alive in a blackout?
Battery warranties.
As mentioned before, a well managed LFP battery, with excellent cell balancing should last 15-20 years.
There's one brand coming in 2025/2026 that promises a 12,000 cycle warranty. 32 years at one cycle per day.
As you would expect the manufacturers are usually ultra-conservative with their warranties.
They really don't want to give you a new battery in ten years time because they let marketing offer too generous a warranty.
So 10 years warranty to 60% or 70% of original output is typical, but the best batteries are a LOT better than that.
Brochure/Datasheets on some of the batteries we install.
Sungrow SBR
Goodwe Home Lynx F G2
iStore/Huawei
Sigenergy
Alpha ESS B5-13
BYD HVM
SAJ B2
Growatt Ark-XH
SolaX T-Bat
SolarEdge Energy Hub
Installation costs.
Installation costs for the battery, consumption meter and backup with a changeover switch are typically $2,000 for all.
The inverter consumption meter is typically $200 for single phase and $400 for three phase.
Sungrow, SAJ, Goodwe (3 phase only) hybrid inverters include the consumption meter.
Backup components (power from the battery & solar during a blackout) is included with Goodwe, Sungrow, SolaX, SAJ and Alpha.
The other brands have a separate backup box costing...priced below as Single phase/Three phase backup box.
Growatt $330/N/A, iStore $790/$1,200, Fronius/BYD $925/$1,475, SolarEdge $515/N/A
Inverters compatible with these batteries.
A few years ago there were very few 'hybrid' inverters, and they used third party batteries like BYD, Pylontech and LG.
Once demand ramped up, the inverter manufacturers started making their own batteries.
So from the list of batteries above here's what works with what...
I've used the format single phase/three phase below...
Goodwe battery - Goodwe EH (5kW)/Goodwe ET (5-30kW) inverters.
Alpha battery - Alpha (5kW) / N/A inverters.
SAJ battery - SAJ H2-V2 (5-10kW)/SAJ H2-T2 (5-10kW) inverters.
Sigenergy batteries- All Sigenergy inverters.
Growatt battery - Growatt MIN-XH, MIN-XA (5kW)/MOD-XH (5-10kW) inverters.
Sungrow battery - Sungrow SH.RS (5-10kW)/SH.RT (5-10kW) inverters.
SolaX T-Batt battery - Solax X1 (5-7.5kW)/X3 (5-15kW) inverters.
SolarEdge battery - SolarEdge Home Hub/Genesis (5-10kW)/ N/A inverters.
BYD HVM battery - Fronius Primo GEN24Plus (5-10kW)/Fronius Symo GEN24Plus (5-10kW) inverters.
(BYD HVM also works with Goodwe and Sungrow single and three phase hybrid inverters above).
iStore battery - iStore And Huawei (5kW-6kW)/ iStore and Huawei (5kW-6kW) inverters.
Other batteries.
There are many other batteries than those listed above...Dyness, Sofar, Solplanet etc etc.
We recently lost one brand, Redback, who have gone into liquidation, but hopefully will re-emerge.
They were an Australian company, and it's never good to see one of our own fail.
But, how all these manufacturers make enough sales/profits to stick around here is beyond me.
What if the price of lithium battery cells fell 50%?
They have. In fact the price of LFP cells is about 80% lower than 18 months ago.
This has resulted in an average 20% fall in the price of most batteries over that time.
Some have been slower than others for the cost savings to flow through which might be an inventory thing.
A 20% fall in price for the complete battery unit following an 80% fall in the price of cells.
That goes to show that the lithium cell cost is significant in the total cost, but not overwhelmingly so.
AC or DC Coupled batteries
AC Coupled batteries don't connect to a solar inverter, DC Coupled do.
DC coupled inverters are called 'hybrids' because they manage both solar and a battery.
Most of the big inverter brands include some hybrid models in their range.
AC Coupled batteries are an option for people who already have an existing solar installation.
Often times however, it's cheaper and better to chuck out the old solar inverter and replace with a hybrid.
Now that the best AC Coupled battery/inverter, Tesla Powerwall 2 is out of production, choices are limited.
The new Tesla, the Powerwall 3 isn't a battery inverter, it's a hybrid, and that makes it ineligible for AC coupling in WA.
There aren't too many other quality options for 'battery inverter' AC Coupled solutions for WA and our unique rules.
This review was written by Andrew MacKeith, Solar4Ever service manager since 2011.