All-in-one or separate components

PEFarmer

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Oct 24, 2021
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7
Hi All,

This is my first post here.

Background: My wife has strong prepper tendencies, which I either tolerate or support, and would like to have an off-grid capable solar system in place in the event of long term/near permanent grid failure. I'm ok with that, but to spend that kind of money, I need to have something that will be paying me back in the interim. I feel like I've found that in the form of a pair of Growatt 3000/24s wired for split phase, connected to about 4k of solar (probably used panels for cost. I have tons of south facing unshaded roof area) and at least one EG4 battery. This would be supported as well by grid power and wired to supply my primary sub-panel in the house that contains all of my 115v loads (When I built/wired my house in 2013, that was how I elected to split the panels. How convenient now) I'd wire it into the sub-panel via an interlock with the main breaker bringing power in from the main panel thereby allowing the sub-panel to normally be fully supplied by the pair of Growatts, but able to be switched back to regular grid wiring via the interlock and main breaker in the event of equipment failure/other. With apologies for the long lead-in, my question is this:

Is the pair of Growatts the best/most reliable solution for the long term, or should I be looking at individual components (mppt charge controller, inverter, etc) and would individual components still allow for "grid support" when solar/battery are insufficient like the Growatts would. I think I've seen inverters that will allow for split-phase wiring, so that doesn't seem to be a problem, but the grid support seems questionable. My overall goal is best reliability given similar costs.

Thanks in advance!
 

mopat

Solar Addict
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Jun 22, 2020
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546
the best/most reliable solution
Tough to say. If your design (panel configuration) keeps the maximum open circuit voltage below 145Vdc and the Growatt's don't fail within 30 days of use they will probably last a long time.

3000 watts from 24VDC, will be more stressful then 3000 watts from 48VDC (SPF 3000TL LVM-48P)

Your post was not clear: Do you need split phase power? What in your house runs 220V?

I run two LV2424's for each side of my breaker panel, but they're not set up split phase as I got rid of all those appliances
 

PEFarmer

New Member
Joined
Oct 24, 2021
Messages
7
Tough to say. If your design (panel configuration) keeps the maximum open circuit voltage below 145Vdc and the Growatt's don't fail within 30 days of use they will probably last a long time.

3000 watts from 24VDC, will be more stressful then 3000 watts from 48VDC (SPF 3000TL LVM-48P)

Your post was not clear: Do you need split phase power? What in your house runs 220V?

I run two LV2424's for each side of my breaker panel, but they're not set up split phase as I got rid of all those appliances
Great question about the split phase: Want, but don't absolutely need. Expanded: I currently run my house in a power outage on a 115 generator with an off the shelf adapter that puts both L1 and L2 on one combined leg, works great, 230 devices see 0 volts, do nothing but aren't harmed. I could do this with solar if needed, but there's one sticky wicket: My heat pump water heater, if run on heat pump only mode draws about 350 watts (240v) I'd love to be able to run this off the solar system both to have hot water during an extended outage and realize more monetary benefit from displacing grid power with solar in the interim. This is the one thing that I'd need split phase to make happen.

Edit to add: If I went with split phase, I'd move my water heater over to the sub-panel as it's currently in the 230 panel. Actually have the flexibility to have the choice as I have 2 WH circuits located side by side in my garage to allow for 2 water heaters if needed. I could move one to the sub-panel to run off the solar, and leave the other on the main panel that wouldn't be supplied by solar and have the flexibility to wire WH to either circuit (could even go cord and plug if I really wanted flexibility).
 
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Brett V

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Apr 5, 2021
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304
A conventional electric water heater is a huge load. I purchased a heat pump water heater and except for the surge of the compressor starting, make hot water using about 6 amps at 240 volts AC. I put in a Growatt 6k split phase LF unit and couldn't be happier. For now it's strictly in UPS mode and runs the whole house easily. My grid tie system is indirectly recharging the batteries and I usually have a credit on my electric bill each month. I originally built one 230 amp battery and just picked up sixteen more 230 amp cells to build another battery. Next summer I'll be putting in maybe 8 or10 panels to utilize the mppt on the Growatt and take it off grid as much as the solar capacity allows. I need the 240 volt split phase for my well pump and the water heater. Looking from a prepper standpoint, getting water out of the well was my biggest challenge and the Growatt solved that problem handily.
 

PEFarmer

New Member
Joined
Oct 24, 2021
Messages
7
A conventional electric water heater is a huge load. I purchased a heat pump water heater and except for the surge of the compressor starting, make hot water using about 6 amps at 240 volts AC. I put in a Growatt 6k split phase LF unit and couldn't be happier. For now it's strictly in UPS mode and runs the whole house easily. My grid tie system is indirectly recharging the batteries and I usually have a credit on my electric bill each month. I originally built one 230 amp battery and just picked up sixteen more 230 amp cells to build another battery. Next summer I'll be putting in maybe 8 or10 panels to utilize the mppt on the Growatt and take it off grid as much as the solar capacity allows. I need the 240 volt split phase for my well pump and the water heater. Looking from a prepper standpoint, getting water out of the well was my biggest challenge and the Growatt solved that problem handily.
Agreed about the water heater. To be clear, I'm talking about a heat pump water heater. The inductive power meter I have on mine says it pulls about 365 watts when in heat pump mode (obviously much higher in resistive mode, but that can be locked out). I agree that well water is a prepper challenge. We have 3 domestic wells (and one 50 hp irrigation well) on the farm, but none are close enough to my house to be run on my home solar. I'm continuing to conjure on that.
 

mopat

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LearningIt

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Great question about the split phase: Want, but don't absolutely need. Expanded: I currently run my house in a power outage on a 115 generator with an off the shelf adapter that puts both L1 and L2 on one combined leg, works great, 230 devices see 0 volts, do nothing but aren't harmed.
Isn't there a risk of overloading the neutral by having both legs running at the same phase?
 

PEFarmer

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Oct 24, 2021
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7
Isn't there a risk of overloading the neutral by having both legs running at the same phase?
Theoretically possible, but not at the currents supplied by either my 3400w generator or the solar setup I'm contemplating.
 
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