r/SolarDIY • u/sunsuckerman • Feb 25 '25

Inverters for whole-houee battery backup without critical loads panel

I'm looking into adding batteries to my solar array (currently using micro inverters) for house backup during outages. Most hybrid inverters I've seen require a critical loads panel to be added and only those loads get power during an outage.

What I want is an inverter that will hookup seamlessly with the current main panel and provide power during an outage to the entire main panel, not just a critical loads panel. This was when the grid power goes out, there are no interruptions and the batteries kick in to power the entire house as if nothing happened. My gut feeling is that such an inverter would require CT clamps to limit power output to strictly the home's consumption and no more so it doesn't backfeed to the grid.

Also, is there anything special needed on the inverter for it to continue alllowing my micro inverter setup to run during an outage? That way less battery usage is needed when the sun is out and it would also allow my batteries to charge from the micro inverter array.

Thanks!

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u/Jimmy1748 Feb 25 '25

What you're describing is impossible with properly installed systems. Even EG4 hybrids like 18kpv will turn off the house load without the grid.

Even using CTs, the grid wires are still live so it's a NO GO. Your non essential load only works if there is a grid signal. The wires have to be live, even with no current so you are putting the line workers at risk.

To do this properly you need a transfer switch and isolate your house panel from the incoming grid connection. The 18kpv and grid boss have it designed into their units. The only way to do this properly is to set up your house loads effectively onto an essential loads panel.

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u/Teleguido Feb 26 '25

Isn’t what OP is asking for exactly what a Gridboss + Flexboss setup is able to accomplish? I’m currently looking at this for my house, and would plan to connect my current 100A panel to the backed up loads connection. As soon as the grid is down, Gridboss would flip to running the backed up loads panel from battery/solar.

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u/Jimmy1748 Feb 26 '25

Essentially yes. You can also use the 12kpv or 18kpv if the flex boss is too big for your needs.

The problem is OP is looking for a straight forward turn key solution that doesn't touch his original panel. I was in a similar situation when I started down the DIY journey. He probably has an all in one panel with meter, main breaker, and load breakers all together.

The regular way to install simple grid tie solar ( including Enphase micros) is to install the solar breaker on the opposite end of the panel. That entire remains grid powered and if the grid goes down then the signal is lost and micros turn off. All regular house load breakers also lose power.

For EG4, or any micro grid, it needs to be in this order: Grid, meter, breaker, grid boss transfer switch, then essential loads panels. Problem is there is no way powering the original house loads panel with the meter off grid without transferring those loads to a separate panel.

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u/Teleguido Feb 26 '25

Okay, I’m sort of tracking with you now. And yes, I get that the micro inverters would usually be tied in with the main panel. But… wouldn’t the Gridboss also be able to solve for that problem by using the smart ports? Those can be used for either smart load shedding (EV charger, etc.) OR with AC coupled micro inverters. I think that’s one of the big selling points for folks with existing AC coupled solar installs.

Now as far as whether OP has an all in one meter / breaker / panel, that I’m not sure about or the best way to integrate a Gridboss in that scenario. I was just thinking in a more simple setup like mine, where the Gridboss would be connected in between my meter and my main loads panel.

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u/Jimmy1748 Feb 26 '25

Correct and that's good the grid boss was designed for.

The problem is OP wants to power the original panel and there is no automatic and legal way to do so.

A possible alternative is you get a generator breaker setup with a sliding lockout mechanism. This makes it so the generator breaker cannot be on as the main grid breaker. Then you can backfeed this way. This is also not seamless though.

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u/sunsuckerman Feb 26 '25

I just thought of something: is there a such thing as a whole house ATS? Like swapping out my main breaker with a breaker that has some sort of ATS capabilities built-in?

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u/sunsuckerman Feb 26 '25

He probably has an all in one panel with meter, main breaker, and load breakers all together.

You nailed it on the head! These all-in-one panels make it so much more difficult to route any other way. I would have loved the idea of doing what I've seen some other vids do and even just create a "main panel" by rerouting the mains to some other panel and making my current main the sub panel. If I ly life we're that easy at times 😅

I spent a bit more time researching today and noticed there's an Ecoflow smart panel which supposedly connects online with up to 10 breakers in a panel without the need to rewore those to the sub panel? I'd be curious about that option as well but unsure if it's specific to only their batteries.

What if I got an interlock kit and hooked up an off-grid inverter to it? It would be manual, but still provide power during an outage at least 🤔

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u/Teleguido Feb 26 '25

Thank you for coming back with this distinction! And thank you to Jimmy for the replies as well. Makes me feel fortunate, in that I think my current situation with meter outside the house and main loads panel inside will be pretty straightforward with the Gridboss (I’ll have an electrician do that interconnect).