MisterSandals
Participation Medalist
Handles single daily need.
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Suggestions for whole house off-grid system?
- Thread starter JBoffgrid2022
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MisterSandals
Participation Medalist
Doh, thanks, i missed that.
JBoffgrid2022
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Any thoughts on sizing my battery bank properly to the solar array?
I would have a 114kwh battery bank and (60) x 370-480w bi-facial panels. I calculated the panels to produce 430w which could potentially produce 25.8kw of power. I would imagine this is plenty of power to fill the battery banks but would love your input.
MisterSandals
Participation Medalist
114.688kWh / 5h in August = 23kW of solar panels to charge from empty operating at 100% efficiency
114.688kWh / 2.66h in December = 43kW of solar panels to charge from empty operating at 100% efficiency
114.688kWh / 2.66h in December = 43kW of solar panels to charge from empty operating at 100% efficiency
timselectric
If I can do it, you can do it.
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Wholly cow.
Nuf said.
Nuf said.
JBoffgrid2022
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JBoffgrid2022
New Member
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Dear Lord! Bahahahah
Well okay then.... Back to the drawing board I go!
Well okay then.... Back to the drawing board I go!
Gttnsun
Amps +-
I see people talk about the price of a monthly utility but not talk about the price to replace solar system components.
If solar panels last 30 years, batteries last 20 years and your inverter last 15 years maybe you have a generator on site too?
what is the cost to replace and maintain those?
In my mind the cost of those is your monthly bill.
I live off grid and I do enjoy the energy independence, but it's definitely not free power.
A lot of people seem to like sizing 1:5 to 1:7 in panels to battery
Hedges
I See Electromagnetic Fields!
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Mine is more like 1.5:1 PV panels to (usable) battery capacity. Would increase further with sufficient mounting area.
Because I'm not full-time offgrid, just backup.
Battery charging is regulated down to 0.2C, but plenty of PV to supply daytime loads (if good sun.)
PV panels cost about 20% what batteries do, so overpaneling makes sense to me.
Because I'm not full-time offgrid, just backup.
Battery charging is regulated down to 0.2C, but plenty of PV to supply daytime loads (if good sun.)
PV panels cost about 20% what batteries do, so overpaneling makes sense to me.
JBoffgrid2022
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@MisterSandals, where there is such crazy fluctuations on solar irradiance here in Maine, how on earth would I ever not over power my inverter and keep my system charged in the winter? I am thinking I would not need that much power in the winter too. There's no way I would be using 114kwh per day. I'm thinking I would be closer to 30-40kwh
JBoffgrid2022
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"Ain't nuthin' free in this world..."
Gttnsun
Amps +-
You are looking at buying a solar system at a great time, it is way cheaper now then even 3 years ago
You seem to be on the right track, it's better to plan for the future, loads usually go up not down.
MisterSandals
Participation Medalist
Its your plan, i'm just crunching your numbers.
ksmithaz1
Solar / EV Junkie
Cheapskate!
ksmithaz1
Solar / EV Junkie
If you are building from scratch, to be "off-grid", I'd likely skip the pretty batteries, and grid tie inverters, lots more options these days. Till I'm blue in the face, what matters on your inverter front is your peak DEMAND. Multiple 6000XP, or look into some of the 10KW units showing up out there. I'd get a tall rack of RUiXU's (10x5KWH = 50KWH, $14K).
Over-plumb an outbuilding, build it with room for extra inverters, and a couple of extra tall battery racks, maybe room for 4, plan on buying 2, maybe start with 1. Run 240A AC feed wiring back up to the house run a nice 200-240A panel with lots of breaker slots. (On the off chance you get a couple three EV's or something). All electric 2400sqft home, you will need around 100A as a minimum, High demand items: 5T-HVAC is 25A + HWH 20A + DRYER 20A + RANGE 30A = 95A), I'd shoot for 150A of inverter ~ 36KW, 30 (3x10) would probably work, leave room for one more, could start with 2 and see how it goes.
They make variable / multi-stage compressors for central air, expensive but do it right, it will reduce your current draw/spiking, or engineer for mini-splits as you see fit. Assuming you plan on heat-pumping, with propane backup for heating / generator, leave yourself room for the genny/venting, and figure out a nice big tank and the feed lines. I'd build it with block, minimum 10x12 or something, lay it out, inverter wall, then 4 racks 2ft wide 4 deep. I'm working on this now, I've already commited to the 18K's, at the time I wanted to make sure it would start my 4T-HVAC, they demo'd that on a video. I had lower end units that fell over I had to replace, annoying, but it's only money.
It all kind of depends on how "off-grid" you want to be, and engineer your property and house to take advantage of optimal panel placement. You are likely going to want some ground mounts, and to cover a south facing roof.
Over-plumb an outbuilding, build it with room for extra inverters, and a couple of extra tall battery racks, maybe room for 4, plan on buying 2, maybe start with 1. Run 240A AC feed wiring back up to the house run a nice 200-240A panel with lots of breaker slots. (On the off chance you get a couple three EV's or something). All electric 2400sqft home, you will need around 100A as a minimum, High demand items: 5T-HVAC is 25A + HWH 20A + DRYER 20A + RANGE 30A = 95A), I'd shoot for 150A of inverter ~ 36KW, 30 (3x10) would probably work, leave room for one more, could start with 2 and see how it goes.
They make variable / multi-stage compressors for central air, expensive but do it right, it will reduce your current draw/spiking, or engineer for mini-splits as you see fit. Assuming you plan on heat-pumping, with propane backup for heating / generator, leave yourself room for the genny/venting, and figure out a nice big tank and the feed lines. I'd build it with block, minimum 10x12 or something, lay it out, inverter wall, then 4 racks 2ft wide 4 deep. I'm working on this now, I've already commited to the 18K's, at the time I wanted to make sure it would start my 4T-HVAC, they demo'd that on a video. I had lower end units that fell over I had to replace, annoying, but it's only money.
It all kind of depends on how "off-grid" you want to be, and engineer your property and house to take advantage of optimal panel placement. You are likely going to want some ground mounts, and to cover a south facing roof.
JBoffgrid2022
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I'm just messing with you of course
Never say "No way I'd be using 114kWh" to an unknown moving target lol. But I really appreciate everyone's input, no matter how painful it might be to hear! 
....
JBoffgrid2022
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There will probably be a lot where we plan to build, at least that is what our friends are saying happens. I would like to keep my bottom row of panels at least 3-4' off of the ground. Maybe even designating the south facing portion of the house for roof mounts. I would want to make sure those panels connect to the same inverter and/or inverters so their production is the same. Reason being is I highly doubt I'd be able to fit 60-70 panels on my roof!
