Home battery storage systems...

[Dabop]

This system of solar panels, and batteries, suppling mains quality electric, is common on Narrowboats', all be it small scale.
What is needed is a good understanding of how to charge the batteries properly, Lithium batteries, have very different requirements to Lead acid.
Good quality Pure Sine wave inverters' are needed for modern electronics. A proper multi stage battery charger, to maintain the batteries over winter, as Solar panels produce next to no charge during the British winter, and the batteries will suffer great damage if left less than fully charged, over that period.

Bod.

Actually- 99% of modern electronics not only don't need a pure sine wave inverter- many don't even need AC at all!!
Seriously- anything with a switchmode power supply in it (that 100-250v 50/60hz label on it) will run straight from the DC battery bank of many modern offgrid houses- which often run at 96 or 120vDC, some even higher...

With modern offgrids being so large (10kw, 20kw or even more) of panels and 10kw+ inverters- the days of a 24 or even the 48v banks has passed (I bought my 48v 12kw inverter cheap, because not many offgrid systems here in Oz are that low any more...)

 

[Bod]

Actually- 99% of modern electronics not only don't need a pure sine wave inverter- many don't even need AC at all!!
Seriously- anything with a switchmode power supply in it (that 100-250v 50/60hz label on it) will run straight from the DC battery bank of many modern offgrid houses- which often run at 96 or 120vDC, some even higher...

With modern offgrids being so large (10kw, 20kw or even more) of panels and 10kw+ inverters- the days of a 24 or even the 48v banks has passed (I bought my 48v 12kw inverter cheap, because not many offgrid systems here in Oz are that low any more...)

As I was talking about Narrowboat systems, which work from 12vdc (few at 24vdc) batteries' then a inverter is necessary, certainly some modern electronics are quite fussy about their wave form at these base voltages.

Bod.

 

[NikNak]

Cheers for all the comments so far

So.... via a local council group buying scheme, we've been offered a home battery system. In fact we've been given 4 options.... 2.2kwh, 6.6kwh, 8.8kwh and 13.2kwh.

I should add that we have a 3.6kw solar array, a Solar iBoost water heater, a Zappi will be installed very soon (just as soon as its delivered). And the plan is to sell my (diesel) car and then lease an ev for a couple of years, at least until battery technology settles down and becomes more affordable(?)

Two retirees who's average lecky usage has fallen from (approx) 10kwh per day to 6kwh since the install of solar pv's.

Those who've had experience of home batteries, which setup would you go for.?


Nick

 

[Dabop]

As I was talking about Narrowboat systems, which work from 12vdc (few at 24vdc) batteries' then a inverter is necessary, certainly some modern electronics are quite fussy about their wave form at these base voltages.

Bod.

Same still applies- a switchmode can run quite happily off any waveform, as the first thing it does inside is rectifies it to DC anyway, then uses a high frequency oscillator to 'chop' the DC to a square wave AC waveform (usually in the tens of khz region) ie the same as the old kettering ignition system in principle, then uses that to do the voltage shift through a small transformer (this is the buzz that you can sometimes hear from switchmodes, as that transformer is being fed a square wave essentially) changed to the required voltage and then rectified/regulated

The few devices that actually NEED AC still are voltage locked (ie 110/120 or the 220/230/240 ranges- no multivoltage) and these and devices with motors directly driven from the mains do need pure sine wave inverters...

99% of electronics (ie anything with that 100-250v, 50/60hz label)- doesn't need the added expense of a pure sinewave inverter

Certainly a 12, 24,48, 72, 96 or higher inverter, the input voltage has nothing to do with the output voltage or waveform, indeed you can get quite large 12v inverters (like my 8kw continuous, 16kw peak one) but at the lower voltages, your resistive cable losses and also the currents become rather large- meaning very short, and very thick battery cabling is required... (my inverter at full roar would be pulling close to 800A from the battery bank!!!! over double what my diesel Hilux draws while cranking....)

 

[Dabop]

Cheers for all the comments so far

So.... via a local council group buying scheme, we've been offered a home battery system. In fact we've been given 4 options.... 2.2kwh, 6.6kwh, 8.8kwh and 13.2kwh.

I should add that we have a 3.6kw solar array, a Solar iBoost water heater, a Zappi will be installed very soon (just as soon as its delivered). And the plan is to sell my (diesel) car and then lease an ev for a couple of years, at least until battery technology settles down and becomes more affordable(?)

Two retirees who's average lecky usage has fallen from (approx) 10kwh per day to 6kwh since the install of solar pv's.

Those who've had experience of home batteries, which setup would you go for.?


Nick

A lot depends on the local regs- I'm well and truly out of date re the UK solar/hybrid battery scene unfortunately...
In Australia, you are required to use only approved battery boxes for gridtie systems, which limits you down to Tesla (not very popular here- overpriced for the storage capacity and relatively short life expectancy 10 years guarantee), Huawei- which make a nice piece of kit indeed, BYD- probably the most popular by far, and (despite many not having hard of it in the West- is one of the biggest lithium battery manufacturers and EV manufacturers on the planet) and a handful of others

Because mine is totally offgrid, I had no restrictions on manufacturers, and went for Winston, again a very large Chinese manufacturer, which has been selling offgrid batteries out here in Oz for over a decade, and make single 3.7v cells from 40ahr up to 10000ahr (4 in series for each 12v jump so my houses 48v system will be 16 in series at 400ahr, giving me 20kwh for about two grand less than the Powerwalls 13.5kwh!!!), and have a output guarantee of 20 years at 70%DOD usage, double that of a Powerwall!!!

 

[Spectric]

they usually just have them out on a tube steel structure rather than putting them on their houses - something most landowners here think looks bad - my FIL won't actually get them on his roof because they'd be on the front of his house and he doesn't like the way they look, and BIL who drives a tesla won't have them installed freestanding on his property for the same reason

In the Uk they are being put on the roofs of period properties and really spoiling the characteristics of both the property and the local area. The best place is on the roofs of industrial buildings and large warehouses where they have no impact

 

[D_W]

AT some point, I'd ask the question of whether or not you've taken a position of serving the property, or if it's serving you. My FIL doesn't want panels on his house on the front because he's embarrassed by the way they look. His house is less than 10 years old. I've never challenged him on it, but he lives in a good sun area with a new roof (roofs last about 40 years here with dimensional shingles) and geothermal/heat pump combo heat and cooling.

It's a hang-up type thing. My wife might have it, too - don't know. I'd like to have panels on my south facing roof, but there are trees to the east and west - I already live in a poor solar area (0.7 factor vs. 1.05 250 miles east and 1.3 in the southwest US) and would further limit the hours only to the peak of the day. Our houses are brick and older - they're not "period or nice", but they don't look like complete cheap junk like the new siding houses here do (some of those literally come with sealed MDF exterior trim - they know they're setting you up to replace it in a decade - horrific). I like the idea of the panels on the roof also because an attic here with house length vents will literally reach 150F in the summer, even with the air slowly circulating. It would be nice to capture that radiant energy and do something with it (I'd be lucky also because my south roof faces the back yard, but it's not a differentiator).

It's kind of like the offshore windmill thing here - affluent areas don't want them, but they're bonkers about "green energy". I just have no idea where they think it should go.

Further yet, I guess, we had an opportunity to sell 330 acres to a solar developer last year (a farm, nothing special, not commercial, just a farm). My parents ended up selling it to two amish cousins, half each. The solar development was far more valuable but after two were approved, the township determined that they're an eyesore (in an area where it's perfectly fine to have abandoned cars in your yard). It would've been a multi-year process to work with the utility to get an electric right of way, but probably would've worked out. In the end, my parents didn't want to wait to settle the land as they don't really need the money - I'd imagine the area will eventually be open again to panels, just not yet - people aren't used to seeing them.

We are enormously wasteful here in the states. We grow double the corn acres vs. what anyone actually wants under the suspicious motive of providing "green" fuel. Solar panels provide somewhere around 100 times as much gross energy as the ethanol made from excess corn acres here, but people decry them as "limiting food growing acres" as if wasting half of the corn acres to be forced by mandate on a market that doesn't want them, and on a basis (environmental) that they damage rather than help - as if that's not putting pressure on food acreage (there is no real pressure - we grow more than we eat already). As a family, we're out of owning farmland now, so don't have a dog in fight, but I posed the idea to someone of if they have 200 corn acres, and 100 are used for ethanol (about half the crop year to year), if we put one acre of panels on their farm and they range cattle or grow anything else on the other 99 - something people would actually eat, how is that hurting the food supply?)

Many tangents here, I guess - but the looks thing is something I don't really get. Whoever built the properties originally did so to serve people. When they're not doing that, it doesn't make sense - it's as if we want to turn the whole world into a museum and stand off to the side.

 

[Spectric]

It would have to be a very large capacity battery bank because thinking of a UPS the batteries are connected in "strings" with ten or eleven in each string and then the strings are put in parallel to increase overall capacity. These types of UPS are charged from a three phase supply with an inteligent control and charging system so the batteries are maintained until loss of supply then the controller uses the Dc battery supply to produce the Ac supply to maintain the loads. With only solar panels to charge the batteries then you could discharge faster than the ability to recharge.

A Uk house supplied with a 230 Vac single phase supply protected by a 100 Amp DNO fuse will be around 23kva. For a three phase supply this is about 70Kva.
So you need a large shed in which to acomodate the racks of batteries and is the cost worth it?

 

[D_W]

Just for giggles, I did a calculation. Total US electricity use would take about 11.7MM acres of solar panels right now. That's not a doable case, of course. 90MM acres of corn are planted, and 45MM are wasted on motor fuel that nobody really wants (even in areas where it's grown, it's not really used in greater amounts than the legally required blending level).

Tangent off of a tangent - we couldn't store the energy and use it when needed, but It's kind of telling about priorities. For generations here, we've told farmers how valuable they are (generally making it hard at the same time for a smaller operation to stay afloat), and the message comes through as something less than noble if farm land isn't used to grow excess food that nobody wants. The narrative doesn't serve the purpose.

 

[D_W]

It would have to be a very large capacity battery bank because thinking of a UPS the batteries are connected in "strings" with ten or eleven in each string and then the strings are put in parallel to increase overall capacity. These types of UPS are charged from a three phase supply with an inteligent control and charging system so the batteries are maintained until loss of supply then the controller uses the Dc battery supply to produce the Ac supply to maintain the loads. With only solar panels to charge the batteries then you could discharge faster than the ability to recharge.

A Uk house supplied with a 230 Vac single phase supply protected by a 100 Amp DNO fuse will be around 23kva. For a three phase supply this is about 70Kva.
So you need a large shed in which to acomodate the racks of batteries and is the cost worth it?

One would hope that at some point, the packs coming out of old cars can be repurposed to household use. Tesla describes pack life as expended when 90% of the original capacity is left (which for their cars now is probably somewhere around 200-300k miles. Those 75kwhr packs are still capable of discharging some large fraction of 90% of 75kwhr, which would make them ideal for household use. No clue if anything is being organized for this in terms of market making, but it seems to me if the packs themselves are $9k or so at that size and the old car packs aren't being recycled in quantity here (which at least the last time I checked was the case), then there's something usable if the packs can be put into another envelope that organizes, controls and thermally manages them.

 

[NikNak]

Sorry should have said the batteries supplied will be Pylontech UC2000C's

 

[Dabop]

It would have to be a very large capacity battery bank because thinking of a UPS the batteries are connected in "strings" with ten or eleven in each string and then the strings are put in parallel to increase overall capacity. These types of UPS are charged from a three phase supply with an inteligent control and charging system so the batteries are maintained until loss of supply then the controller uses the Dc battery supply to produce the Ac supply to maintain the loads. With only solar panels to charge the batteries then you could discharge faster than the ability to recharge.

A Uk house supplied with a 230 Vac single phase supply protected by a 100 Amp DNO fuse will be around 23kva. For a three phase supply this is about 70Kva.
So you need a large shed in which to acomodate the racks of batteries and is the cost worth it?

You obviously have no idea of how far battery tech has advanced...
;-)
I am currently running off 10kwh of lithium batteries (half my eventual bank of 20kwh) and they are literally the size of a medium to large suitcase...

That's half the bank (2 series strings of 4 x 400ahr to give 12v in parallel)- that gives a 12v, 800ahr bank ie 9600whr or 9.6kwh

That will be what I am using to run my house and shed/workshop (I measured my usage at my previous mains house and it was 7kwhr a day), so nearly three days of full usage for house and shed in the two sets of those batteries...
That's a 1.25L bottle of coke next to them for scale...
(I am currently running at the 12v level instead of the 48v the house inverter runs at, purely because of the caravan- its lights, builtin TV and water pumps for the shower and sink are all at 12v, plus I had a inverter available from my ute that runs at 12v (8kw) which was why I stayed there for the temporary install until the house is built)

 

[D_W]

Looks nice, and scaleable, too. I've seen packs like that here sometimes referred to as "cell tower batteries" as they end up hitting the secondary market, but I'm sure not all are cell tower batteries. The significance of them is they are more compact than a typical lead acid setup by a long way, and easier to handle and scale. I'm guessing they don't have a hydrogen offgas issue, too.

 

[Dabop]

Looks nice, and scaleable, too. I've seen packs like that here sometimes referred to as "cell tower batteries" as they end up hitting the secondary market, but I'm sure not all are cell tower batteries. The significance of them is they are more compact than a typical lead acid setup by a long way, and easier to handle and scale. I'm guessing they don't have a hydrogen offgas issue, too.

The mob that made mine, make single 3.7v cells from 40ah to 10000ah (no thats not a mistake- a ten thousand ahr 3.7v single cell...) so you can spec up practically everything from a small UPS supply, to powering a factory... just select the cells you need...
Once people actually start looking at what is already available, it becomes rather funny watching those who literally don't even have the beginners knowledge start proclaiming that 'this and that can't be done'
LOL
(the biggest cells available from that one company can make huge 'batteries' of any voltage you want-imagine a 12v 'car battery' that literally weighs more than most cars!!!- and could crank an engine literally non stop for MONTHS on end- got the money- you can buy it...)
:-O

 

[Droogs]

@D_W I was left gobsmacked after seeing this this morning

 

[D_W]

Not a fan of the water wasting, but the climate change blame wears me out. The issue is that everyone and their brother wants to take more water out of the colorado river, and as more money settles along the basin, more people waste water in grass, etc.

The whole water rights thing in the west is a huge issue. There are a lot of highly water intensive permanent crops (almonds, etc) that get bigger and bigger as the population of the US grows. They need to consider just using less water, but nobody actually wants to do it. As that video mentions, the areas like that one tend to have cheap water because there are no legacy costs yet associated with the water system. We end up paying more for water here where it's more or less unlimited, a lot more, because we have infrastructure and pensions (deficits) attached to the water supply.

 

[pe2dave]

I'm spending my "eco" funds on insulation and controlled ventilation first. By the time that's done, the capacity and costs of units on the market will have improved. I have loads of room for solar PV/HW panels. I would not consider a wind turbine under any circumstances.
You may learn something, if you haven't seen it already, from the irrepressible Robert Llewelyn's experiences with a Tesla Powerwall (and other "eco bling") in his house -

Very interesting Woody - thanks for sharing. I cringe at the cost of that installation!