14.4 KW solar, 40.96 kWh backup, 2 solark 15k inverters, off grid family home, doable or delusional?

[ksmithaz1]

Interesting

 

[Zwy]

If you get/store thermal energy from a givenn source, e.g. boiler & storage tank, using that as thermal input to heat pump, no extra energy is obtained.

Not the way this works.

Heat pump needs excess quantity of lower grade heat.


You would get as much energy using stored hot water directly. Only thing heat pump does is boost temperature, could make radiators put out more. What it can do is cool off the tank faster if you need higher grade heat.

Plan is to add a buffer tank of lower temp that is not part of thermal storage. Eventual plan is radiant staple up and other low temp emitters, perfectly suited for a heat pump. I will also add a propane fired condensing boiler for when I might be gone and temps are well below 0°F. Arctic heat pumps can work that low but they do suffer efficiency losses. The heat pump is for excess solar mainly as a heating dump load.

The 1400 gallons of thermal storage is not for the heat pump. It is for accepting the heat from the gasification boiler. Gasification requires thermal storage in order to maintain high refractory chamber temps and capture the heat energy from the high fire. Thermal storage temp of 180°F is too high for a heat pump to add heat (unless a 2 stage heat pump is used), thus the need for the buffer tank where mixing can occur to have a lower water temp for low temp emitters. It isn't any different than using a thermostatic valve to control temps to low temp emitters. The advantage of using low temp emitters combined with thermal storage is the thermal storage can be used from 180°F down to 110°F instead of a high temp emitter which is run to a minimum near 140°F. This extends the time between batch burns.

Wood boiler and thermal storage will be in a separate building than the house. Hot water will be piped off the top of stratified thermal storage to the house where it will be mixed with colder water in the buffer tank. The water in the buffer tank is then circulated thru the low temp emitters. The advantage of hydronic heat is the buffer tank can be heated from several sources, it doesn't matter as long as it is heat energy.

 

[Banjoman]

Same here- the US is 'power mad' when it comes to many things- 'utes' with 4 times the horsepower of my 8 tonne tilt-tray truck (and fuel consumption to match), HUGE electrical demand (some US fridges use more than my entire 3 bedroom house with three people living in it- including a 'gadget mad' older guy (guess who that was lol) and a teenager who never learned what an off switch was...)
Our daily consumption was around 7-10kwh a day- in total... running off an 80A 240v mains supply and 6kw of gridtie solar, the electricity bill was usually- zero...
(in fact we often got a few bucks back from them...)
Seriously lol
(they direct deposited the 'bill' amount on the due day straight into our bank account if it was a 'negative bill')
View attachment 194507
Many offgrid houses here in Australia comfortably run multiple A/Cs, cook on electric and have a lifestyle that it is hard to tell you are actually running purely from solar...
Of course solar here seems to be a lot cheaper than the US as well which helps- people quoting multiple tens of thousands for systems is crazy high price wise (gridties here cost about $3500Au or about $2300US- thats fully installed, no more to pay,and will give you about 35kwh a day in generation, where a 10kw system (requires 3 phase on at the house) is about $6500Au ($4200US) again fully installed, no more to pay, and will generate about 52kwh a day...

My own offgrid system cost me under $2000Au for ex gridtie panels (secondhand, from an installer doing upgrades/repairs) 72x 250W panels totaling 18kw of panels, the most expensive thing was the battery bank ($11800Au) for 20kwh of LYP batteries (better than LFP for either high or low temp applications) 16x400Ah cells- the total system cost $17500Au in total for everything... ($11400US)- sufficent to run a workshop with a mill and metal lathe, welders, air compressors etc, and a 3 bedroom house with A/C- in total that 18kw of solar will be getting up to 90kwh a day...
And I plan to buy an EV this year to boot lol (looking at the BYD Atto3)
all offgrid...

If you don't mind asking what is an LYP battery? First Ive heard of this.

 

[Bop]

If you don't mind asking what is an LYP battery? First Ive heard of this.

LYP is a form of LFP specifically LiFeYPO4- basically Yyitrium is used as a doping agent in the battery- it is slightly more expensive than LFP, but has a usable temperature range of -45C up to 85C
This is the spec sheets for my battery pack here (20kwh nominal, 16x400Ah cells)

Unlike L/A or LFP, they can be charged down as low as -20C (-4F) with no throttling , down to -45C (-50F)with throttling (reducing the charge rate from a maximum of 3CA down to 1CA max (thats 1200A down to 400A on my cells), and the same with the upper end (which is where I like their performance, being in N/E Australia, we regularly get temps in excess of 40C(105F) for weeks on end) unlike LFP and L/A which need to start throttling above 40C, the LYP doesn't need to start throttling until its over 60C(140F), and stop charging at 85C(185F)... in which case, the battery temperature is the least of my worries lol
(people in Marble Bar still wouldn't have to throttle LYP- despite it hitting 52C there a few weeks ago- thats 125.6F!!!)

They have a slightly poorer charge density than LFP (slightly larger physically and slightly heavier for the same storage capacity, by about 10%) but for household use thats not an issue... and the ability to accept full charge rates up to 60C more than makes up for it...

Not exactly new- they have been on sale here in Australia since 2008, elsewhere since 2002...

 

[G00SE]

Is that what Winston cells are, or is that just a similar cell casing?

 

[Banjoman]

LYP is a form of LFP specifically LiFeYPO4- basically Yyitrium is used as a doping agent in the battery- it is slightly more expensive than LFP, but has a usable temperature range of -45C up to 85C
This is the spec sheets for my battery pack here (20kwh nominal, 16x400Ah cells)
View attachment 195002
Unlike L/A or LFP, they can be charged down as low as -20C (-4F) with no throttling , down to -45C (-50F)with throttling (reducing the charge rate from a maximum of 3CA down to 1CA max (thats 1200A down to 400A on my cells), and the same with the upper end (which is where I like their performance, being in N/E Australia, we regularly get temps in excess of 40C(105F) for weeks on end) unlike LFP and L/A which need to start throttling above 40C, the LYP doesn't need to start throttling until its over 60C(140F), and stop charging at 85C(185F)... in which case, the battery temperature is the least of my worries lol
(people in Marble Bar still wouldn't have to throttle LYP- despite it hitting 52C there a few weeks ago- thats 125.6F!!!)

They have a slightly poorer charge density than LFP (slightly larger physically and slightly heavier for the same storage capacity, by about 10%) but for household use thats not an issue... and the ability to accept full charge rates up to 60C more than makes up for it...

Not exactly new- they have been on sale here in Australia since 2008, elsewhere since 2002...

Interesting... any of these LYP's come in server rack form I could get in the states?

 

[Bop]

Yup- mine are Winstons...
AFAIK there are no rackmounts for LYP (love to see the server rack that could hold 216kg/477lbs of cells which is what my 20kwh bank weighs lol)

 

[Banjoman]

Looks like they may actually have a LYP server rack if you scroll down into the description on this page: https://lypbattery.com/winston-battery/48v-100v-lifepo4-battery/

 

[Bop]

Looks like they may actually have a LYP server rack if you scroll down into the description on this page: https://lypbattery.com/winston-battery/48v-100v-lifepo4-battery/

That's new (admittedly I haven't been to their website for a few months- basically 'semi retired' these days, and building my place is the priority...)
ETA- although that is using their LFP cells, not the LYP ones... and is a reseller...

Winstons LYP range thats the manufacturers page, not a resellers page...