PowerBoost inspired hybrid house

[JoeWpg]

I see now - each inverter controls 120V and one side of the split phase 240 - so they are not in parallel. Cool.

You have not shown any neutral or ground connections to the mains or PB. I would look carefully into the inverter specs regarding bonding (ie neutral to ground connections). The PB is internally bonded and cannot be disconnected - usually main power is also neutral-ground bonded, which would lead to GFI trips in the PB. Do the parallel Victrons somehow ensure all power pulled from mains or PB is always balanced between the 2 x 120V split legs? Cant see how this works...

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[powerboatr]

Since owning my 2023 7.2kW PowerBoost, we have used it's incredible generator/inverter capability to power critical circuits in our house during multiple grid failures. Critical circuits include, refrigerator/freezers, furnace, security system, well pump and strategic lights and outlets. It has been flawless. The only problem has been grid failure when I am not home with the truck...duh! Soooo...

Of course, I could install a standby generator but that seems soooo 2010's. I have decided to build a battery backup system, with some twists.

System Requirements:

• Easily power the critical circuits currently powered by PowerBoost.
• Enough stored energy ( batteries ) to power critical circuits for three days.
• Expandable energy storage
• Include automatic transfer function <20ms - UPS mode - in grid down.
• Include automatic transfer function to generator source ( PowerBoost ) to recharge batteries and power circuits

Simply put, I am building a home UPS system that will automatically recognize when either grid or PowerBoost is available to recharge batteries and power critical circuits. We rarely have grid failures over three days and with this system the PowerBoost should easily keep us going for weeks

Still in the planning stage, but very close to build stage. It should be fun!

Yes, of course, this offgrid design is most often used in solar or yacht systems, but I think the PowerBoost is the perfect secondary power source.

Here is a drawing of what I have come up with so far. I am NOT an electrician - obviously.

Oh, almost forgot! I did confirm a 30% Clean Energy tax credit for the system that can be carried forward until 2035. Cool!

Tell us more on extending tax credits

 

[fwunder]

Tell us more on extending tax credits

https://www.irs.gov/credits-deductions/residential-clean-energy-credit

You can carry forward any excess unused credit, though, and apply it to reduce the tax you owe in future years.

 

[Gros Ventre]

Be careful paralleling the two solar sources. It isn't as simple just connecting them to produce 240VAC. If they are designed to parallel, good. If not be careful.

 

[fwunder]

I see now - each inverter controls 120V and one side of the split phase 240 - so they are not in parallel. Cool.

You have not shown any neutral or ground connections to the mains or PB. I would look carefully into the inverter specs regarding bonding (ie neutral to ground connections). The PB is internally bonded and cannot be disconnected - usually main power is also neutral-ground bonded, which would lead to GFI trips in the PB. Do the parallel Victrons somehow ensure all power pulled from mains or PB is always balanced between the 2 x 120V split legs? Cant see how this works...

Very good questions!! I am still studying and trying to learn but am assured by those who would be programming the units and drawing the final plans that it will work. The neutral/ground connections definitely elude me and why I did not include them in my drawing other than in sub panel. When I have final drawings I will definitely share.

Thanks for asking!

 

[fwunder]

Be careful paralleling the two solar sources. It isn't as simple just connecting them to produce 240VAC. If they are designed to parallel, good. If not be careful.

It is designed for this.

https://www.currentconnected.com/product/victron-48v-quattro-5000va/

I show the 5kVA with that link because I am strongly considering that unit(s) due to its 4kW output rather than the 2.4kW output of the 3kVA unit(s). Much more future proof.

 

[Gros Ventre]

Read thru the flier. It is not clear to me that the paralleling they speak of is that of using it to produce 240VAC. So take your time.

 

[fwunder]

Read thru the flier. It is not clear to me that the paralleling they speak of is that of using it to produce 240VAC. So take your time.

Thank you, I will.

My new favorite book:

https://www.victronenergy.com/uploa...imited_book/43562-Wiring_Unlimited-pdf-en.pdf

 

[Mszczewski]

Very interest to see how this works out. If it goes well for you I might be right behind you.

 

[Gros Ventre]

Thank you, I will.

My new favorite book:

https://www.victronenergy.com/uploa...imited_book/43562-Wiring_Unlimited-pdf-en.pdf

I have looked thru the section on AC in that book. They always seem to refer to paralleling at the 120VAC level. However when you are thinking of 240VAC the paralleling is different in that you are going above and below the neutral level. They just don't address this aspect. That's why I'm uneasy with the idea. I think its a good thing to pursue as it then opens up the entirety of running a house set up with utility wiring and the full 7.2kW of the PB.

 

[ReverendQ]

Since owning my 2023 7.2kW PowerBoost, we have used it's incredible generator/inverter capability to power critical circuits in our house during multiple grid failures. Critical circuits include, refrigerator/freezers, furnace, security system, well pump and strategic lights and outlets. It has been flawless. The only problem has been grid failure when I am not home with the truck...duh! Soooo...

Of course, I could install a standby generator but that seems soooo 2010's. I have decided to build a battery backup system, with some twists.

System Requirements:

• Easily power the critical circuits currently powered by PowerBoost.
• Enough stored energy ( batteries ) to power critical circuits for three days.
• Expandable energy storage
• Include automatic transfer function <20ms - UPS mode - in grid down.
• Include automatic transfer function to generator source ( PowerBoost ) to recharge batteries and power circuits

Simply put, I am building a home UPS system that will automatically recognize when either grid or PowerBoost is available to recharge batteries and power critical circuits. We rarely have grid failures over three days and with this system the PowerBoost should easily keep us going for weeks

Still in the planning stage, but very close to build stage. It should be fun!

Yes, of course, this offgrid design is most often used in solar or yacht systems, but I think the PowerBoost is the perfect secondary power source.

Here is a drawing of what I have come up with so far. I am NOT an electrician - obviously.

Oh, almost forgot! I did confirm a 30% Clean Energy tax credit for the system that can be carried forward until 2035. Cool!

Careful, you may inspire me to spend money

I have been contemplating a similar application. We currently have battery (2x Powerwalls) backed solar with important loads on a subpanel. I suspect our current controller (Tesla?) may be able to determine when to use a) utility grid b) solar c) batteries and/or d) truck, truck playing the role of generator. If not, I am considering a transfer switch between the solar/batteries and the truck power. So, if grid is down and solar/batteries deplete the system could use truck power.

Please do keep us informed as to your progress with these Victrons, they might have a use in my application.

Anybody reading this know of anyone who has added truck/generator to a battery backed solar system?

 

[HammaMan]

Have you considered an AIO? You haven't listed your loads, but it's not uncommon for a unit like this to run a whole home. They're also parallel capable and run in UPS mode. Adding solar is as simple as adding panels.
https://signaturesolar.com/eg4-flexboss21-16kw-ac-hybrid-inverter-48v-split-phase-21kw-pv-input/

If you want the gen input the other variant is what's needed (expect none of the units to work w/ the PB's GFI system)
https://signaturesolar.com/eg4-18kp...v-12lv-48v-split-phase-120-240vac-ul1741-cec/

They also have a smaller unit that puts you more in line w/ the pair of victrons
https://signaturesolar.com/eg4-12kp...t-phase-rsd-all-in-one-hybrid-solar-inverter/

Also, regardless of unit, be prepared to have to use a separate standalone charger that charges the batteries off of generator directly as the GFI of the PB may present a problem and trip its breaker.
https://signaturesolar.com/bigbatte...eatherproof-lithium-battery-charger-58-4v-dc/

 

[fwunder]

Have you considered an AIO? You haven't listed your loads, but it's not uncommon for a unit like this to run a whole home. They're also parallel capable and run in UPS mode. Adding solar is as simple as adding panels.
https://signaturesolar.com/eg4-flexboss21-16kw-ac-hybrid-inverter-48v-split-phase-21kw-pv-input/
...

Thanks Hammaman.

Yes, I have looked at the Eg4 options. In fact the Eg4 LL batteries were my first choice - price/performance. Now the Pytes are gaining my support.

I am somewhat partial to Victron mainly because of their worldwide footprint and experience in offgrid and marine applications. I am a long since retired charter boat captain. I also have a couple of Victron components ( mppt charge controller and smart shunt ) in my travel trailer and will be upgrading to the Multiplus in the future. Other than that, I do agree that the Eg4 products do offer a lot for the money!

I am awaiting a response from Victron on the specific PB neutral-bonding GFI ground fault thing we have all experience and found workarounds for. I could tell you what I did for the last two years, but then I don't want to start another "one of those" threads.

Thanks again for the suggestions! I may be an old dog, but I can still learn new tricks!

 

[fwunder]

Also, regardless of unit, be prepared to have to use a separate standalone charger that charges the batteries off of generator directly as the GFI of the PB may present a problem and trip its breaker.
https://signaturesolar.com/bigbatte...eatherproof-lithium-battery-charger-58-4v-dc/

My first answer from Victron:

The quattros have by default switching neutral ground switch.
When the quattro connect to the generator or your inverter that device should have the neutral ground bond.

The ground relays are programmable. I have included a Cerbo GX which gives remote access to the system for engineering support/monitoring. I'm feeling pretty good this will work. Yes, It's a bit of investment.

 

[fwunder]

@HammaMan

You should know I'm currently having lots of discussion with Victron experts. You may be correct with regard to the PB GFI issues. Trying to work it out but right now it is looking like the chargeverter option may make more sense. Might be a little less convenient, but I would save a little by going with split phase Multiplus instead of Quattro. And give me more generator options ( I have three ). Still digging!

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