So with a server rack battery, inverters, and solar array on the roof... Do you use the system to power the house and only pull from the grid when needed? Or do you leave the batteries full, pull from the grid and then you have 100% backup if the power goes out? Or do both, and if bad weather is coming, keep the batteries charged?
If I put in a server rack battery on a house, solar on the roof... use it for backup or all the time?
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chrisski
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IMO batteries for a household backup are just way too expensive. They need to be used to justify the cost.
I’ve lived in my area 11 years and never had a power outage. That’s halfway or all the way through the life of a properly maintained battery.
More economical and practical is grid tied with no battery, but life is not about money saved.
I’ve lived in my area 11 years and never had a power outage. That’s halfway or all the way through the life of a properly maintained battery.
More economical and practical is grid tied with no battery, but life is not about money saved.
42OhmsPA
What's in a title?
And what about that one time the power does go out and you're out of town so your freezers full of meat and other food spoil?
Edit - I think I see the point you're trying to make, if you have a battery cycle it.
Oh I’m doing a battery and having a generator plug in too. I’ve had way too many power outages over the years. My dad just went through hurricane Ian, lost power, and his $25000 generator crapped out 3 hours in. Alternator ate a bearing. Hopefully batteries are more reliable.
Ampster
Renewable Energy Hobbyist
And they are more flexible for peak shaving, assuming they are connected to a good hybrid inverter.
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Hedges
I See Electromagnetic Fields!
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Power was out in Oakland before the windstorm, then in Redwood City due to wind storm, about 24 hours each.
PG&E crews go to work, power is restored, freezer coasts through. That takes care of most people, most places, most of the time.
I'm presently more concerned about my Sunny Island or paralleled breakers having an issue and shutting off the freezer, so would switch direct to grid if going on a trip. Until I rig up a reliable deadman transfer switch.
Battery backup power costs a premium.
Batteryless backup with grid-tie, something that automatically cycles on and off day/night during power failures, would be useful; some of those are manual.
With poor or no net metering terms, batteries would be used to improve return. With time of use, save PV from low times to export for larger credit during peak rates.
I use AGM strictly for backup. Not cost effective, rather a luxury. Actually, I use it mostly to enable PV direct to loads like air conditioners; it supplies starting surge and keeps grid-tie system up during power failures rather than storing a full day's power for the night.
Server rack is getting reasonable enough, around $6000 for 20 kWh, for 24/7 power of reasonable home loads at least when there is good sunshine. Would need to manage loads when cloudy.
Redundancy. AC battery charger would have kept battery charged. Or PV panel? But why only 3 hours? I've driven a car several hours without alternator, and generator should have no load other than ignition coil.
PG&E crews go to work, power is restored, freezer coasts through. That takes care of most people, most places, most of the time.
I'm presently more concerned about my Sunny Island or paralleled breakers having an issue and shutting off the freezer, so would switch direct to grid if going on a trip. Until I rig up a reliable deadman transfer switch.
Battery backup power costs a premium.
Batteryless backup with grid-tie, something that automatically cycles on and off day/night during power failures, would be useful; some of those are manual.
With poor or no net metering terms, batteries would be used to improve return. With time of use, save PV from low times to export for larger credit during peak rates.
I use AGM strictly for backup. Not cost effective, rather a luxury. Actually, I use it mostly to enable PV direct to loads like air conditioners; it supplies starting surge and keeps grid-tie system up during power failures rather than storing a full day's power for the night.
Server rack is getting reasonable enough, around $6000 for 20 kWh, for 24/7 power of reasonable home loads at least when there is good sunshine. Would need to manage loads when cloudy.
Redundancy. AC battery charger would have kept battery charged. Or PV panel? But why only 3 hours? I've driven a car several hours without alternator, and generator should have no load other than ignition coil.
chrisski
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Just get some good power requirements for your battery backup. A couple of Tesla powerwalls will not power my two ACs very long, but without running air conditioning could last days if I am careful.
If you have frequent power outages, then it’s much more worth it.
My battery build I’m looking at is a solar powered level 2 charger, powered with split phase 240 volts around 6 kw, but that is turning out to be way to expensive (EDIT with 15 kWh to 20 kWh of batteries).
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Ampster
Renewable Energy Hobbyist
I think of a level 2 charger as and EV charging station? How is that related to a battery build?
chrisski
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More about a the power requirement of 6kW which I’d want a 15 kWh to 20 kWh battery requirement than the inverter and charger actually being actually used for Level 2 charging.
I’m curious about the OPs power requirements he’d like to fulfill with the batteries.
I really like the idea I saw on youtube where the guy had a server rack (25kw) with dual victron 3000watt inverters to supply 240v. He put a sub panel between the main panel and the inverters. All the critical loads were moved to the sub panel. So in a power outage, the inverters power the sub panel and somehow there must be an automatic transfer switch that disconnects the main panel. I didn't pay too much attention to that part. I don't have any delusions of running A/C or heat pumps on the battery. Just critical circuits- some lighting, internet, TV, fridge, microwave, freezer, garage doors, and if the house I buy (still shopping) has gas applianced, then run the light stuff like furnace blower, etc.
I have no clue how the solar panel array ties in. I would like it to supply as much power as possible and charge the batteries.
I have no clue how the solar panel array ties in. I would like it to supply as much power as possible and charge the batteries.
wiseacre
Solar Addict
I have a modest system built for backup (2000w of panels, 19200wh battery bank and a cheap Eco Worthy 3500w, 24v inverter)
After seeing one of Will's videos about the MOES ATS I bought one
My system is now powering 5 aquariums, tv, internet and wifi router.
During winter system often switches to grid with the constant load. Days on end of dismal cloudy skies takes it's toll and if I think there is a chance of the grid going down I'll adjust the ATS to use grid power
In summer I add an air conditioner to the constant load
After seeing one of Will's videos about the MOES ATS I bought one
My system is now powering 5 aquariums, tv, internet and wifi router.
During winter system often switches to grid with the constant load. Days on end of dismal cloudy skies takes it's toll and if I think there is a chance of the grid going down I'll adjust the ATS to use grid power
In summer I add an air conditioner to the constant load
I just don't know how much of the system is "up to code" and be can inspected, and how much of that I "DIY" after the panels and transfer switch are installed.
That's the guy I was referring to!
zanydroid
Solar Wizard
This is only part of the story. The 24 hour restoration was about 99.9%, but streets in the affected areas with downed power lines serving only 10-20 customers got triaged to the back of the line wrt work crew priority. There was also a larger block of customers that came back a day later, namely the ones using a distribution line over 101 that required shutting down the freeway.
Anyway what I’m saying is, there’s at least 100 households in core peninsula suburbs next to 101 that were out for over 48 hours.
My takeaway has been to revise my risk model. If you live in a neighborhood with vulnerable local distribution infra, it doesn’t matter how in civilization you live, you have elevated risk and mean time to recovery
Ampster
Renewable Energy Hobbyist
6kW is only 25 Amps, which should be easy at most RV parks. You have an RV, correct?
chrisski
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I do. I rarely am plugged in and usually boondocking.
42OhmsPA
What's in a title?
'that guy' is the owner of this amazing forum, if you didn't know.
My opinion, DIY it all if you can.
Multiple benefits such as understanding it when something go wrong and only being able to blame yourself for
It really comes down to your religion. For environmental or policy reasons you want to minimize export mid-day and minimize grid consumption from ~4-10PM. For economic reasons, you want to minimize grid export at low payback hours, and minimize grid import at high charge hours. If you like anarchy, you want to export everything between 11AM and 1PM. If you like to support oil companies then maximize import between 4PM and midnight. If you are a prepper, save every watt since tomorrow could be the last day the grid exists.
As with most things, balance is likely the best approach. My goal is to limit my grid current to under 10A at all times, and keep enough reserve capacity for minimal operations for one day. I figure that pretty much smooths out all the various religions.
As with most things, balance is likely the best approach. My goal is to limit my grid current to under 10A at all times, and keep enough reserve capacity for minimal operations for one day. I figure that pretty much smooths out all the various religions.
Oh wow, I didn't know that. I watch a lot of his videos. Very cool. I can DIY, my concern is what exactly needs to be done within the realm of the electrical permit so I can grid tie and sell back to the grid, etc. Once that's all inspected, then put the battery back up and inverters in myself if they aren't exactly up to NEC. Or do I do everything and then go for electrical inspection?
I've done Reliance Generator transfer panels (3 houses so far) myself and never bothered with permits/inspections before. But getting that fancy 2 way electrical meter is going to put me on the radar as far as getting a permit.
