Solar battery standalone install options?

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Talkiet

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#311692 7-Feb-2024 17:21

(I will speak to an electrician once I get a feel for what's available)

I have a 6.6kw solar system with no battery. I typically use power through the day, but so far have been charging my EV at night because (at the moment) my buyback rate is the same as my offpeak usage rate. That is changing (inevitable - I am surprised it took this long) so I am thinking about batteries.

I know they don't really make sense financially. I am however curious what sort of battery storage option for home makes the LEAST WORST SENSE.

My inverter is a Huawei sun2000 unit so the simplest option would be a Huawei battery unit. Last time I checked, the $$$/kwh for them were at least twice as bad as relatively generic LiFePo4 battery banks but obviously the install is way way simpler.

I've found that "advice" from most solar installers is coloured much more by the solutions they offer rather than a best fit solution for a particular client - so I am hoping there's some specific knowledge out there that can help me ask properly targeted questions of suppliers and installers..

With all that preamble, here are my naive questions. I would really appreciate if anyone that's been through this could correct me, or add relevant context - or even point to someone that will work to determine a best fit solution.

Are there solutions available that can integrate with the Sun2000 that are non Huawei and use generic LiFEPo4 battery banks?
Are there solutions that can be installed that are separate from the existing solar inverter, but can communicate well enough to know when to charge from solar, and from offpeak mains if required?
Do these solutions allow relatively simple additions of additonal battery banks in the future? (Could I install 5/10kwh now, and add more in the future with just some big cables and maybe a management cable?
Do these solutions easily allow for continuous power in the event of a mains failure, or do they require physical interlock changeovers to isolate the mains network before they can be powered on in the event of a mains failure?
Can the battery system be easily transported to a new house? (I know moving the solar would be a pain, but the BMS/inverter/battery bank seems intuitively not too hard to move around?)

I am sure I have got some of the terminology wrong but I also think that if you've read this far, you get what I am going for.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

billgates

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#3192116 7-Feb-2024 20:29

1. Only the Huawei Luna or the LG RES high voltage batteries are compatible and will work with the Huawei Sun2000 inverter. LG RES both the high and low voltage models were discontinued couple of years back so your only option for your inveter to talk natively with the battery is the Huawei Luna. Huawe's system is good but not great. I am not a fan of high voltage Solar PV because they are extremely proprietary as you are finding out. You cannot DIY your own battery setup unfortunately.

2. Any AC coupled system like Tesla Powerwall 2 will work as a seperate system from the existing Huawei inverter you have. The new Powerwall 2 inverter is hopefully now available in NZ announced and released 3 months ago and has better power output at 7kW although battery size is limited to still 13.5kWh. You will need to buy there gateway and you can safely add up to 5 to 6 of these in parallel. The single gateway supports up to 10 powerwall but it just dosent works reliably so 5 or 6 is the sweet spot number.

3. Because the powerwall 2 has integrated inverter and battery, moving it is possible but is very heavy and ofcourse the mains wiring will need to be disconnected so best to just sell.it with the house.

Do whatever you want to do man.

Talkiet

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#3192125 7-Feb-2024 20:40

Thanks for the response. I have a philosophical objection to anything related to Elon Musk so the Powerwall is off the table for me - but presumably if I ask about "AC coupled systems similar to Powerwalls" I'll get sensible responses.

Ultimately I am hoping to find something that can just have the generic 4U rackmount LIFEPO4 battery boxes connected. In my mind that makes it somewhat modular from a capacity (investment) perspective, and more easily portable if needed.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.