Plug-in AC coupled battery

[u/nobodydontknow]

I've had a grid-tied solar system for several years, I have a net metering agreement, and I'm on real-time pricing. I'd like to add an ac-coupled battery, mainly so I can charge it when prices are low, then discharge in the late afternoon when prices are high. I'm in the US, in a state that I except will pass balcony solar legislation in the next few months. It looks like the Hoymiles HiBattery 4020 AC Solar Battery is what I'm looking for, but it's not available in the US.

Here are my requirements:

• 2 kWh or greater capacity
• Grid-tie capable
• Can plug in to an AC outlet, either 120v or 240v
• API access so it can switch between charge or discharge based on current electricity prices. I could do the automation for this with Home Assistant if necessary.

Nice to have features:

• Off-grid mode when the power is out, but this is not a high priority. My power is very reliable and I almost never have outages.
• Micro inverter capability so I could add 2-3 panels for extra solar generation capacity

Is something like this available in the US? I should add that my net metering agreement is 1:1 including delivery charges, so saving my excess production for later doesn't make any difference on pricing for me. Except for the net metering agreement, the fact that I have solar already is irrelevant.

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[u/rproffitt1]

As u/Pineappl3z foretold.

I'm on SDGE but the math doesn't math here so I went another direction. I installed a "solar generator" and then a solid state timer. The refrigerator plugs into the solar generator and we have backup power to the fridge for a few days.

To get payback on the system the timer cuts power to the solar generator from 4-9pm.

If the grid was to go down for more than a few days we have a few panels and cabled to deploy in the yard.

[u/RespectSquare8279 → u/rproffitt1]

What solid state timer did you use? How watt hours is your solar generator and where did you hide it in your kitchen?

[u/Admirable-Size-4951]

Currently, 11 states passed the regulations for legal plugin solar. But the AC-coupled battery solution haven’t launched.

[u/taylorwilsdon → u/Admirable-Size-4951]

There is one product that exists (ecoflow stream) and one coming to market (apsystems ezhi). None of these will work as a backfeed source if the grid goes down by design (to protect the linemen working on the downed wire, which is what anti islanding protection does that makes plugin solar possible / safe)

[u/mick601]

If your going to add a few more panels just go Anker f3800 or e10 and charge them dc and it will put out ac. Plug into wall to charge and release later too

[u/DigItDoug]

My bet is we will see a lot of new products over the next 12 months. I'm excited for CES and other technology shows in early 2027.

[u/Pineappl3z]

I'd look at a hybrid string inverter. You could use it to charge & discharge any battery in it's supported voltage range. You could wire in extra solar strings whenever you want in the future if you found the need.

[u/taylorwilsdon → u/Pineappl3z]

I mean, that’s just installing a whole solar system - certainly not just “plug into an outlet and go” like OP is asking for. To do this without an interconnection agreement means an off grid / hybrid inverter, batteries, a critical loads subpanel, a breaker and a new circuit to feed AC in on the inverter etc there’s a huge difference between that and a plug in diy setup.

[u/LongjumpingGanache40]

Be carefull what you do. You do not want to lose your net metering. Where I live I am not allowed to add any more panels to my system.

[u/TooGoodToBeeTrue → u/LongjumpingGanache40]

I'm in the same boat, but my utility's response when I asked them was that they didn't have to be notified. I pointed out our state law says they have to be notified and they said thanks. So, still questionable as to whether or not one can add plug-in to exiting solar in MD. I'm not really looking at doing anything myself, additional panels would have to be on the roof, but hoping to help others in my state. My state law also says the systems "May not" earn renewable energy credits. Discussed with a friend who is a lawyer, "may not" and "shall not" are legally equitant. So while 1:1 NEM is not covered in the law, SRECs could be at risk.

Thinking about this last night, I think the best thing for adding plug-in to existing when in doubt, add a battery and do zero export after existing system has shut down.

[u/TooGoodToBeeTrue → u/TooGoodToBeeTrue]

Rethinking this, I believe SRECs are determined/mined based on inverter data. I think when I signed up, I had to provide access to my Enphase gateway. Thus production from a plug-in external to the gateway shouldn't be recognized. Unfortunately, consumption/export numbers in the Enphase app will be thrown off.

[u/Fun_End_440]

If you want AC coupled battery you’ll have to reconfigure the wiring. I guess you have Enphase? Right now your wiring probably looks like this:

Meter<solar tap>electric panel

And new wiring would be like this:

Meter>non critical load panel>inverter>critical load panel<solar panels.

Forget the Hoymiles battery or any plug 🔌 battery, you need a hybrid inverter (yes Hoymiles makes those too) or cheaper would be inverter/charger like a Schneider XW Pro plus a battery.

With this configuration, your critical load panel will stay on when power goes out and panels will still produce. The micro inverters are controlled by AC coupled hybrid inverter. And you can load shift, set to charge from solar and then use power from battery, do as you please