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OffGridInTheCity

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Note that packs 5, 16, 21, 44, 45 have dropped off the "cliff" by around the same amount. I see the same issue in my system, and it's an almost sure sign that one cell in each of those packs have died. Either detached/blown fuse, or popped CID.
Thank you for the comment. I'm slated to move pack 5 later this year, and that will give me a window to investigate for this.

Packs 1 thru 14 are all the same 'grey' modem cell from Battery Hookup that tested very well... and I've wondered why this would occur. I put it down to OPUS testing being pretty fuzzy somehow... but that's just a fuzzy thought rather than anything actual. It would be nice to know
 

OffGridInTheCity

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Neighbor sold their house and I was checking zillow.com. Found this pic of my ground mount from their deck. I had wondered what it looked like. Shows you what I mean by keeping a 'low profile' (only 20deg) to blend in with neighborhood - looks like it was a good decision as it doesn't jump out in the view. Its hard for me to believe - but *many* folks do not like panels :(
1626896721802.png
 

hbpowerwall

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Doesn't look out of place at all... Someone once said to me - "A home isn't complete without solar"..
 

OffGridInTheCity

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I also have some mounted at a similar angle. Awesome during the summer, sucks during winter. Maybe mounting additional panels almost upright on the other fence would nicely balance out the output over the seasons?
Agree (about winter) and AGREE on more panels - but I promised the wife... no more panels. I'm working on her - maybe if I build her a greenhouse :)
 

italianuser

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Feb 25, 2020
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Neighbor sold their house and I was checking zillow.com. Found this pic of my ground mount from their deck. I had wondered what it looked like. Shows you what I mean by keeping a 'low profile' (only 20deg) to blend in with neighborhood - looks like it was a good decision as it doesn't jump out in the view. Its hard for me to believe - but *many* folks do not like panels :(
View attachment 25670
Oh that does looks great! :love:

Wife... wife... There's a simple solution for wife:

small_diamond.png medium_diamond.png trilogy_diamond.png
LOL:ROFLMAO:
 

OffGridInTheCity

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I'm in Southern Oregon USA.

Smoke from massive forest fires is really taking a toll on PV production this year. Its been continuous for most of August.
PV production for Aug is down to 1,636kwh from last year's somewhat smokey Aug 2020 that yielded 1,899kwh.

The smoke lessons the heat (less AC power required) but it's not proportional - its a net loss in the goal of attaining 100% off-grid and one needs extra PV to compensate.

The worst day was 45.6kwh PV - which is 57% of what it should be on a clear day. Not as bad as a bad winter day of clouds/rain/low-sun but still pretty bad.

Here's what it looks like at the worst - visibility down to 3 blocks
1630508311699.png


Here's what it looks like when it's better.... - 6 block visibility
1630508392973.png

2 posts above you can see what a clear day looks like - the mountain ranges (about 10 miles away) are mostly obscured all month. The wind shifts and we get a couple of hours of clearer air as sun goes down but then right back to full smoke thru the night.
 
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floydR

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The smoke has been bad here in Sacramento too although it has been clearer the last couple days.
Later floyd
 

100kwh-hunter

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Mar 2, 2019
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My dear lord....look who was a very busy bee......

Okee my plans for myself that could turn your plans or give you an idea or two?

A while ago i stumbled upon a guy that harvested/stored his energy from solar into water...
Just dig a hole into the ground insulate with a minimum rd value of 6 with pir sheets or exp or spray foam(pro type water proof btw), get some pvc pond foil, fill with water..
For one person to get comfortably thru those winter months is 1500 liters enough if kept on 85-90 C
One word of advice...make sure that the water is coming out of the crane at least at 48 c minimum.

My house has a 8000 litre water basement(from the old days for drinking water before the plumbing).
Take a guess what i did whit that...

I thought his name was David Poz, thank him for the idea and not me.
Needed in my case:
Two solar panels.
One 48v water heating element.
200 meters of floor heating hose.
Some electronic control equipment.
Insulation.
Pvc or epdm foil
Im my case not even 300 euro's total.

Insulate your house!
To live at neutral you will need to achieve:
For a flat roof a rd value of 13.
tilted roof(45 degrees) a rd of 11.
walls need 8(six is the absolute minimum)
Floor 5.

Your windows need to be a "triple" glass.
When done all this properly, you dont need heating equipment.

If you want help with this or have any questions send me a pm, i have a insulation company (thus a real professional insulator)i can tell you everything you must know and how to do it yourself.

My house? we don't have a home heating system anymore or a wood-stove, when we cook we must open the windows, outside minus 10 C inside plus 24C...520m3 air space..just a warm water boiler(without tank) for insurance and a 1 kwh heating radiator both gathering dust..
Centralised air circulation system with 0 to 5% continues fresh air feed with simple idea of a house has always under pressure and warm air wants to go up :cool:.

And your battery must be bigger? more storage?
Call some car yards and add some of those?

Very good job done

With best regards Igor
 

OffGridInTheCity

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@100kwh-hunter - I appreciate your comments and kind words :)

I do have 3 x 2500 gal rain-harvest water tanks.. and have speculated a bit if I could use them somehow. The immediate problem is I can't insulate them to store hot water. Also, it's not clear the net comparison to hot-water heating vs heat-pump (electrical) heat in my mild temperate zone.

According to my measurements it took an average of 39kwh/day to heat my 2600sq ft house with a top-end whole-house heat-pump and 'average' (1997 standard) insulation. I wonder what the 'hot-water' / 'forced air ducts' equivalent would be.

Back to water - one can easily see PV -> Hot-Water. If only there were only a way to do Hot-Water -> Electricity. Then I could use the natural sun on the water tanks -> Electricity. They get up to 90F/32C in summer time just by sitting out in the sun. This does contribute to lower hot-water heat-pump kwhs (200kwh/month winter -> 140kwh/month summer). Maybe 1kwh due to hotter ambient air (more efficient) and 1kwh due to 90F water (less to heat).

Again with water tanks - I look at storing energy by lifting these tanks in the air. After all 2000gal of water is roughly 2000 * 8 = 16,000lbs or 8 tons. However, when I did the math of raising them 6 feet and then running a generator as they went back down 6 feet I got numbers like 200w total per day. Kind of like wind and water turbines and even gas/propane/steam generators - it seems to take incredible amounts of physical push to get any decent wattage.

Panels are just amazing inventions .... :)
 
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100kwh-hunter

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I will give you a proper reply that you deserve tomorrow, i am a bit to tired now, yes they are amazing inventions
 

100kwh-hunter

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Those are serious water tanks

What i would do with first one:
I don't think they will ship to the US of A, price wise i dont even think you want that.
But i am very sure there is a simulair product over there.
Keep the next rules as basic rules:
Make sure your barrel is full and with a water temperature about 85F/30C
Make absolutely sure that the foam your are going to apply can handle a heat of 230F/110C, some foams will not take higher temps as 190F/90c or even 165F/75C and will get brittle.
Practice on a sheet of wood, before starting to spray on one of your tanks
Most packs needs to be pre heated to 85F/30C, i use some simple electric dog blankets.

The rest will be a bit the same as Divid Poz:
View: https://www.youtube.com/watch?v=ryJmtItfaXQ

Instead of using copper coils from boilers for heat exchangers you could use those plastic floor heating tubes.
One coil for floor heating or radiator heating, your closed system.
And one coil connected to your drinking water supply.
Make your coil for drinking/shower water a 110 yard or so, so the water will have time enough to get the heat from the water.

Dig that one into the soil, it is big enough to heat up your house, shower, dishes...

All you need are some 48v water heating elements a small circulation pump(50-55 us gal/200 litres an hour is more than enough, give it time)
Some small regulation electronics with a small sensor, warmer than 190F/90C cut off the panels, below 190F open the panels.
Make sure all of your plumbings are isolated aswel to prevent extra heat loss.
Get pir sheet of 4 inches thick and a "flat" wood drill (speed drill?) extend with a copper/alu/steel pipe of 3-3.5 foot
Wedge the drill in it, pir does not need a lot of torck.
20210911_170807.jpg
Cut the sheets in 4x4 inches length wise, drill a hole thru the middle, shove your pipe in it, next.....
Between the joints use insulation foam, i don't think you can get my favourite foam but any similar to "fm330 or fm350" will do its job perfect.

39kwh/day to heat my 2600sq ft house
:eek::eek::eek:
My house is double the size and we use not even 9 kwh, if we start cooking we must open the windows.
Next to the amazing inventions is insulation.

If only there were only a way to do Hot-Water -> Electricity.
I would hesitate (not really btw)to do this, but as a experiment it would be very nice: create steam.
What i did for one of my school projects was a sheet of rockwoll in a wooden box of 20x40 inch and 10 inch high.
I put on top some copper pipe with a centre to centre distance of 4 to 6 inch and 1 inch above the rockwool.
2 inch higher i had nailed a epdm pond foil on it and cover the whole thing up with a glass sheet.
Connected to the water pipe and waiting 5 minutes, we could made very hot coffee.

Once i did the same experiment on my pond with a 28 sq ft sheet...the pump was a bit to weak to push a needed amount of water thru it, it was coming out boiling with full sun on it.
On a Saturday morning the pump was jammed with algae, pure steam was coming out.

Oke we are going to second base:
Heat up the steam more to get it more dry: 230-255F/110-125C equals ~12 to 16 bar of pressure(considered as hi pressure for in a steam loco!), now this would make a nice set up to run a steam cylinder to get a generate going (dont run off to get a big boy's or the AA20's cylinder equivalent)
Steam cylinders are pretty easy to make if you can handle a reamer and can do some silver soldering.
But be careful please, steam is not only very hot but also incredibly strong, pay attention when your are going to make your valves and your connections.
Low pressure steam can do the same 212-230F/100-110c equals ~1-12 bar.
If they could do it in 1820-1840, then we can do it better

With the other two i would also dig them in for rain water harvest, one for the garden and one for washing machine (shower) and toilet.
Filter up to 130 micron with a small pump in it and some oxygen ball.
For drinking water you need a setup that would need more space, technology and measurements than your power wall, but yes it can be done.
Preferably a contentions system of 10 to 20 gal an hour, the exes water can be returned into the filter.
An on demand system, nope.
Both cases will also drain your wall faster than you can charge it, thinking of uv-c, ozon, hi pressure pump, filters.
You want to get some dirt, industrial pollution and bird droppings out.
Especially the droppings are making it expensive.
Yes i hear you think: what about the old days...
We did not have industrial pollution thus healthy bacteria that good do the job easy, less dirt in the air also.
If you want to get a ruf idea, google for koi pond filters for a starting set.

Btw lifting a bucket of that size....got any idea what structure you must have to support that amount of weight....
Sorry but the myth of the bricklayer and his bucket of bricks is playing in my mind now...up and down and here we go up again.

With best regards Igor
 

spacecabbie

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Nov 30, 2021
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8
ATS+UPS (Go-Power + APCs) for 6,000va of power for computers, tv, coffee-pot (things that cannot be interrupted during PV/Grid daily switch-overs)

View attachment 16610

The APCs have 18650 7x7 battery packs with iSDT balancing/BMSfrom left-over cells:)

View attachment 17171
Hello,

I had actually asked this in a facebook group if it was possible to replace the 12v lead/acid packs in these ups for custom build lithium ones, since you seem to have done just that mind sharing how what bms en how is it connected to ups ?
 

OffGridInTheCity

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Hello,

I had actually asked this in a facebook group if it was possible to replace the 12v lead/acid packs in these ups for custom build lithium ones, since you seem to have done just that mind sharing how what bms en how is it connected to ups ?
I'm using 7s7p 18650 battery builds with Chargery 8T BMSs.
Here's the spec sheet for the 8T - http://chargery.com/BMS8T.asp
Here's a place to buy one - https://www.chargerystore.com/index.php?route=product/product&product_id=86
Chargery requires an external relay that you must provide, here's what I used in the pic - https://www.amazon.com/gp/product/B0122Z6VZS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

***BUT any 7s BMS will work
BatteryHookup (trusted provider in US) has 7s BMSs and you can add a bluetooth dongle etc and phone app - https://batteryhookup.com/collectio...-bms-w-low-temp-cutoff?variant=37388971049122
DALY BMS is another popular choice.

An APC 1500 maxes out at about 1200w@120v which is 1200w/24v = 50a. So a 50a (or higher) is fine - you would adjust this based on the UPS max power you use.


The APC UPSs as charge up to 27.64 which is about 3.95v/cell. Well below the 4.2v max but also high enough for significant power in the use case of the grid going off and the UPS has to provide power for a few minutes. On the bottom end, the APC UPSs shut-off at about 3.0v/cell (21v) which is within specs of 2.7v/2.8v/cell for 18650 - so again, this is safe.

Here's a pic - just 7s7p with Chargery BMS + relay taped on top with original Anderson plugs for plugin into the APC. Don't be distracted by the extra anderson plugs - I use this APC at my work desk and tap off 24v to power the iCharger X8 for charge/discharge tests.
1638374502628.png

Not pretty! - Taped up to hold Chargery BMS/Relay in place and so things won't make electrical contact with the sides of the metal APC box, and I didn't bother with the shunt as I don't care about over-current or ah in/out. :)
 
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OffGridInTheCity

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My goal continues to be: A functioning home 100% off-grid. The realities (rose colored glasses are off) of having a 100% off-grid functioning home - with at least some modest heat are crashing into reality this winter.

Look at the last 6 days of PV from a 13kw PV array (45 panels)! Last year I only had a max of 2 days in a row like this but there's no end in sight right now - could be 7 days or 10 days or ?.
1638577382428.png
This is not enough for a functioning home. I have the 40 emergency panels, so (in an emergency) I can double these numbers to 12kwh/day... but I need more like 30-40kwh/day to keep the house livable!

I'm thinking about 2022 plans.....
1) Going to see about 24 more panels on the west roof. PV watts says +30%. With 24 more panels (3s) + 39 emergency (3s) in addition to the existing 45, that's 108 panels = 14kwh! as the bottom number in these patches of heavy clouds.

2) 14kwh is still not enough for some level of heat. So I think I'm going to break down and gather 10 x 100lb propane tanks (220gal total) + a generator. I can use one of my AIMS 12,000w inverters for 120a of charging.

3) Planning to add 40kwh to the battery bank for 121kwh total. Need to work on an algorithm to parse out extra battery power over several days to even out to 40kwh/day in winter. At 14kwh of PV, that's an extra 26kwh from battery each day - and can do maybe 3 days of this on 121kwh battery bank. But then - generator!

*I understand I can skip the heat and let the house get down to 35-40F for several days... and use the 14kwh for cooking, maybe hot-water, but how miserable!

Panels work, but there are limits.
 
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Oberfail

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Jun 22, 2021
Messages
247
Another idea, what about those Solar Water heater Panels? Those should be able to collect more warmth / heat from the sun than solar panels with a heat pump with the same size. They can at least provide a base level of warmth at home, solar and grid can provide what is needed on top of it.
 
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Cheap 4-life

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Aug 3, 2020
Messages
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This is why people generally do not use heat pumps or electricity to heat their house and be totally offgrid.. they usually use wood boilers or propane etc. Also generally people who are fully offgrid have much smaller homes that use less power. I use roughly 15kwh a day to operate my 1500sqft home. In the summer I use air conditioning so it’s much higher in the summer..
 

OffGridInTheCity

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Appreciate the comments - and I offer this discussion mainly to share real-world numbers trying to run 100% on PV solar. Its not all roses :)

Another idea, what about those Solar Water heater Panels? Those should be able to collect more warmth / heat from the sun than solar panels with a heat pump with the same size. They can at least provide a base level of warmth at home, solar and grid can provide what is needed on top of it.
Appreciate the comment but I'm not sure hot-water panels are that much more efficient than electricity generating panels + heat-pump in 40F/5C temps. I could run lines under the wood floor of the house but the water piping / setup is daunting!

I'd be interested if someone has efficiency comparison metrics or maybe a use case? I have trusses / wood floor so it would need to be something like this - metal plates attached to underfloor for heat-transfer from water pipes...
1638634853759.png

For now, I'm using all my available space for PV panels.

This is why people generally do not use heat pumps or electricity to heat their house and be totally offgrid.. they usually use wood boilers or propane etc. Also generally people who are fully offgrid have much smaller homes that use less power. I use roughly 15kwh a day to operate my 1500sqft home. In the summer I use air conditioning so it’s much higher in the summer..
Yes sir - agree with you. The house is 2600sq ft. Full wasteful heat using heat-pump in my situation takes up to 1200kwh/month (40kwh/day) in dead winter whereas AC maxes out at around 900kwh/month (30kwh/day) and of course during summer I'm averaging 60kwh/day - no problems staying cool.

Our climate is mild and I'm sure I could maintain adequate heat on 775kwh/month (25kwh/day) by lowering house temps and only running mid-day with higher ambient/more-efficient-heat-pump temps. This would work on 'on average' with 31kw PV (108 panels) except for 6 days (and counting) in a row of dismal/heavy clouds! Can't make a battery big enough to span the gap.

As I've lamented before "wood" based solutions are obvious in Southern Oregon which is mostly forest, but this is where being 'in the city' works against me big-time!
- outside boiler for heat - requires permits and city is not good with this, but maybe I could have some DIY setup standing by.
- wood-stove won't fit in my home without *major* city/permit issues according to 'guys' we've had come out. The city is anti-wood burning due to pollution in the valley.
- power a steam engine? @rossco1948 make these you can buy - but they're more on the relm of 1000w max. It just takes a lot of mechanical power to create electricity!
- power a sterling engine for generator? - can't find one to buy and probably like the steam engine - don't know relative efficiencies but would likely take a lot of wood burning.

"wind" - none wind to speak of.

"water" - nothing.

"other alternatives" - not bit enough property for things like large-compost piles that generate heat or horizontal ground heat-pump. Rocky undersoil prohibits DIY drilling down 40 for earth based heat-pump and can't imagine getting equipment in the yard for deep drilling much less city permits et.
 
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cak

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Mar 14, 2021
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I'd be interested if someone has efficiency comparison metrics or maybe a use case? I have trusses / wood floor so it would need to be something like this - metal plates attached to underfloor for heat-transfer from water pipes...
I live off grid and grew up living off grid. We heat with wood which sounds like not an ideal option for you. We do have solar hot water panels but they do basically nothing in the winter because the days are too short to bring the water up to temp(northern MN). I have also noticed that partly cloudy days the solar hot water does nothing but the solar still brings in a decent amount. Based on all that I have decided that for my uses extra solar PV and an efficient heat pump water heater would be the way to go.

As to thoughts on ways to improve your situation. Something I am sure you have heard before and have probably looked into is just to reduce the need which with heating being dominant for you and you say you have mild winter conditions more insolation and maximizing southern window solar exposure could get that huge heating load a little lower. Insulation, Insolation, Insolation :) Are you aware of the Passive House Standards? It takes a lot to go the whole way with that but when done properly even really cold MN winters can stay warm with very minimal added(beyond the natural window gains) heating.

As another thought that I have considered for myself but my load is low enough it hasn't made sense yet is hydrogen as energy storage(different type of battery). I imagine you have significant excess energy during the summer months so the idea is you electrolyze that extra solar energy into Hydrogen which can be stored in propane type tanks and with minimal modification fun propane appliances. Then you use that Hydrogen in the winter to heat ether directly with combustion or a fuel cell to produce electricity for your heat pump. The upfront investment hasn't made sense for me but with your high load it might be more efficient/cost effective for saving that summer energy for winter when you need it.

Or how most folks do it is to use the utility grid as the "battery" with net metering selling the summer power back to the grid and then buying in the winter
 
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