Thoughts on a battery bank for the home ...

[danpass]

Hello everyone. I've been brainstorming my idea for some time and believe I need to start with the inverter.

A whole-home battery bank system that runs the house, where the battery bank is charged by the grid, solar, generator and any combination thereof.

I believe the inverter is the nexus to this system, where it is between the grid and the home’s breaker panel, electrically speaking.

Is there a whole-home inverter that:

will pass grid power while charging/floating the battery bank? And automatically switch to battery if the grid goes down? (essentially a giant 240V online UPS)

accept solar input?

accept generator input?

I’m not concerned about selling power back to the grid, if that helps simplify anything.

Thanks.

 

[sunshine_eggo]

Hello everyone. I've been brainstorming my idea for some time and believe I need to start with the inverter.

A whole-home battery bank system that runs the house, where the battery bank is charged by the grid, solar, generator and any combination thereof.

I believe the inverter is the nexus to this system, where it is between the grid and the home’s breaker panel, electrically speaking.

More important to identify your power and energy needs.

Is there a whole-home inverter that:

will pass grid power while charging/floating the battery bank? And automatically switch to battery if the grid goes down? (essentially a giant 240V online UPS)

Yes. Most inverter/chargers work this way, but their switch over is typically 20ms - not as good as a UPS, so you might see some disruption in the changeover.

accept solar input?

Only if it's a combined "all in one" (AiO) that includes a MPPT with it.

accept generator input?

Yes, but you will need to choose which on most inverters, i.e., their input can accept AC from grid or generator but not both. The Victron Quattro can be simultaneously connected to both grid and generator, but it will only use one.

Grid/genny selection can be made very simple with an automatic transfer switch.

I’m not concerned about selling power back to the grid, if that helps simplify anything.

Tremendously. Grid interaction is a whole 'nother layer of complexity and expense.

Probably worth a look at the DIY checklist in my signature.

 

[danpass]

Ok cool.

House size: say 1500sqft, 2-3 ton central A/C, etc and in hot humid south FL lol

The inverter and battery bank would be the primary source of power, maintained/kept up by solar during the day, the grid at night and generator when needed (hurricane then grid down, cloudy days and so on).

It would be neat to solar feed whole house and float battery then pull from grid only when needed (ie at night).

it would be nice to be able to feed inverter with solar and generator at the same time.

Basically an inverter that would be able to choose the best source, automatically and manually.

An inverter I can scale into.

At first it may only be the inverter and one of those LiFePo4 GYLL batteries, no solar, and a 2,500 genny lol.

A battery that will keep up a couple of power hungry medical devices overnight and scale up from there over time.

So really just starting with the inverter lol

 

[sunshine_eggo]

Ok cool.

House size: say 1500sqft, 2-3 ton central A/C, etc and in hot humid south FL lol

2-3 ton A/C steps it up a notch

The inverter and battery bank would be the primary source of power, maintained/kept up by solar during the day, the grid at night and OR generator when needed (hurricane then grid down, cloudy days and so on).

revised.

It would be neat to solar feed whole house and float battery then pull from grid only when needed (ie at night).

This would require a very powerful inverter and a lot of solar.

it would be nice to be able to feed inverter with solar and generator at the same time.

I'm not aware of a piece of hardware on the planet that does this. By default, when AC input is attached to the inverter, it passes it through the AC to the loads and uses surplus to charge. The grid and generator sine waves won't be in sync, so it can't be done.

You could charge the battery with a separate AC-DC charger powered by generator while the unit is running on grid.

Basically an inverter that would be able to choose the best source, automatically and manually.

Any single source, yes.

An inverter I can scale into.

At first it may only be the inverter and one of those LiFePo4 GYLL batteries, no solar, and a 2,500 genny lol.

A battery that will keep up a couple of power hungry medical devices overnight and scale up from there over time.

So really just starting with the inverter lol

If you plan to build a scaling system, you need to design the final system and then figure out how to piecemeal it or scale it up. Otherwise, you'll be replacing major (expensive) components as you go.

Again, the DIY checklist is the right place to start.

 

[danpass]

Yes, so which inverter would serve the final system?

That inverter would be the first part of the puzzle.

The GYLL would merely be the first battery in that system (if using the GYLL, EG4, whateveritscalledthisweek lol)

 

[sunshine_eggo]

Yes, so which inverter would serve the final system?

One that meets your power needs.

 

[koobs]

You need to find your final maximum power draw. By what you've said above, it sounds like you need at least an 8kw unit, or perhaps 2x 5kw units.
The only inverter I can honestly recommend is the one I'm using, the Deye 5kw. I think its called the Sol-ark in the US. It is a very customisable multi-modal inverter that can pretty much do what you're asking. However you'll need some significant rewiring at your switchboard to set it up as you've described.

 

[schmism]

any of the parallel all in ones will do this.

Fair warning I have between 15kwh and 20kwh in battery and its only enough for 120v critical loads. Not nearly enough to run AC and other 220v appliances.

Typical whole house versions you want, you're looking at like 15kw of inverter 20+kw PV and 30-50kwh of battery.

 

[koobs]

That's a lot of power consumption for critical loads only. Our house is about 8-15kwh per day for critical loads. When we're not using the AC for heating or cooling, we wake up with at least 50% left on the 15kwh battery. (16x EVE 280Ah + 8.6kw solar with 5kw inverter)
If you use your power thoughtfully, it can go a long way.

 

[danpass]

Ok, thank you.

It looks like the Sol-Ark 12 (or 15) will work for the house (electrical code, etc). Assuming everything lit up all at once it might hit 12kw so maybe the 15kw is better, for that one time, in the whole year, that everything surged at once lol.

That takes care of instantaneous and the heart of the system, perhaps add a soft start to the A/C

Scaling the battery bank will take care of steady state run times.

Then determine what can be done with solar (HOA and all that lol)

My generator plan right now is a 30A connection. I imagine that will be enough to at least keep the batteries up during the day (without solar). off at night for quiet time [unless critical to keep it running] until the grid is back up. The genny I have now is an inverter 2500, nice, quiet, fuel miser, also runs on propane and that puts out 14A steady state. Enough to at least offset the draw down until some solar is added (or get the bigger inverter genny)

My experience is based on the time when the power was out for eight days at a prior house and I only had a noise producing smoke and fume genny with extension cords. Very problematic until a genny inlet was installed. Still had the monster genny that wasn't enough to turn over the A/C but too much to be running for the regular stuff; fridge, microwave etc, and burned far too much fuel for such a small return.

 

[danpass]

Ok, I'm revising the system.

At least the initial part but going to start a new thread.

 

[yaq]

Hello everyone. I've been brainstorming my idea for some time and believe I need to start with the inverter.

A whole-home battery bank system that runs the house, where the battery bank is charged by the grid, solar, generator and any combination thereof.

I believe the inverter is the nexus to this system, where it is between the grid and the home’s breaker panel, electrically speaking.

Is there a whole-home inverter that:

will pass grid power while charging/floating the battery bank? And automatically switch to battery if the grid goes down? (essentially a giant 240V online UPS)

accept solar input?

accept generator input?

I’m not concerned about selling power back to the grid, if that helps simplify anything.

Thanks.

The only one that meets your specifications is Studer's Next3 15 kW

https://www.studer-innotec.com/media/document/0/quickguide-next3.pdf?keyword=next3

there is a US version and you can put several different battery banks and several different PV fields as well as several ancillary injections (generators, wind turbines etc) in a multi-unit version.
With a beast of this standard, a BMS that outperforms all its competitors: "TAO BMS"
( I chose the TAO BMS with the Next3 because it offers possibilities to create charge and discharge scenarios of the battery banks by controlling the inverter )