On-grid domestic battery storage

mmmmikey

zeupater wrote: »

particularly those with average or lower than average demand!

Hi again - yes indeed!



Time for another energy audit I think. Having sequenced the use of higher-power devices to stay within inverter limits when the sun shines, could find myself trying to parallelise the use of low power devices to ensure that I don't run below the export threshold for the batteries. Miniscule gains at this end, of course, but they all add up - reminiscent of some of the widely reported British Cycling incremental gains. As you've pointed out in recent posts, quite challenging measuring accurately at these low levels, particularly anything other than simple resistive loads.


I only have about 18 months data for the new house and have made various changes during that time, so a lot is based on estimates and assumptions, although with a few years previous experience of playing with this and data from the last house, estimates are generally stacking up.


My aim is to eliminate as much of the 1000kWh or so of my annual peak rate usage as I can - this component of consumption is reasonably well spread through the year. If I can cover 80% of that with a 4kWh battery that's good enough for me from a cost/return perspective. Not a money-spinner but enough to make the battery a justifiable toy.



Not unrealistic to get to the stage where well over 95% of my annual usage (which includes heating) is at off-peak rates, and the controls are in place allow me to charge batteries/store energy at any time of day without reatricting myself to E7 hours. So I'll be able to select a tarriff purely on the basis of the lowest TOU rate as they become more available.



Thanks Mike

Solarchaser

zeupater wrote: »

Hi

Excluding the sofar system, installation etc of course !!

Don't forget, your own system was expanded from a pre-owned 2.4kWh base to 7.2kWh represents just over £310/kWh, so applying the 80% as above would be a tad under £400/kWh plus to which most would need to add installation & sign-off costs ...

Just checked for indicative prices for that 7.2kWh setup & around £3900 seems to pop up quite often, so add a small 19" rack with space for possible future expansion (double to 12U?) then that's likely £4100 ... so around £570/kWh before installation ...

What's a Powerwall these days? ... not looked for a couple of months, but £450-£550/kWh (depending on package!) fully installed including ancillaries & VAT ??

Yes, accepted that there's a huge difference in battery capacity and how this dilutes the base cost of the control systems etc, but alternatively the PW2 has a slightly larger (20%) nominal charge/discharge rating and allows short-term peaking (does anyone know for how long? - I assume a few minutes max!) to around 5kW, which would likely suit baseload + standard kettle or soaking-up PV generation cloud edge effect etc, so it may simply mean that parallel or multiple systems wouldn't be required for many (/most) ...

What I'm trying to convey is that in order for the industry to not be tarred with the same brush as the 'double glazing' salesman used for decades, expectation management is quite important on what we all hope will soon be a consumer product. It's not a price-point that's possible to achieve if you cut corners or buy pre-owned, it's what the consumer would do, and they (/we?) don't all hold the relevant skill-set & qualifications to install & appropriately sign off a DIY installation ... I doubt that anything would change on that front unless/until guidance is changed, all homes are equipped with commando sockets and all systems are effectively PnP (That's 'Plug & Play', not 'Post & Packing' before acronyms are unnecessarily raised again! ... ) ....


HTH
Z

To be honest I think I covered what I said fairly well, that FOR ME the pylontech offered the best bang for buck, meaning as I added on modules that's what they would cost.
You are indeed correct I purchased an me3000sp and one battery, for £750, so FOR ME that still equates to £375/kWh.

However if i was to buy it new, instead of paying the £2250 that i paid, I'd now pay £3075
You may well have found ones for £3900, but who would pay that when you can get it from Ebay no less at £3075.
*turns out I cant post links*
So from that it would be (again using useable, not stated) £3075/6kw =£512/kWh.
I mounted no racks, the batteries sit on the floor under the wall mounted sofar, so no extra cost, still at £512/kWh.
Installation surely couldn't be more that £2-300 surely, so at the 6kw system maybe £562/kWh?

In comparison to the edf powervault offer of £600/kwh, which was already discounted by £2k, and although the powervault includes inverter, it replaces your own, so the fit would decrease.

Price of power walls, not sure tbh, but each time I've looked at them, no-one had any stock, so it was a non starter.

Pnp to me is positive negative positive, transistor
Plug and play is p&p

Solarchaser

I cant edit for some reason, so to add the powervault says it will do 5kw output for... second, hence why I just quoted its constant output

zeupater

1961Nick wrote: »

It is possible to source a ME3000SP, 3 x Pylontechs, 2 mounting clips, A/C & DC isolators, & DC cables for £3085. That's about £430/kWh The cost of installation will depend on how much you can do yourself. The cheapest way, & to conform, is to install everything yourself & then get a sparky to connect it to the consumer unit for you.

The cost of my 12kWh system installed was £380/kWh. If you went all the way to 19.2kWh it'd be down to £346/kWh.

Pylontech also make a US3000 plus 3.5kWh battery. Discounts are poor at the moment but it might not be long before they catch up with the US2000 plus discounts.

Hi

However, what I'm trying to convey is that for the the majority of people the option would (as in many other cases!) be to enter into a single supply & install contract & have some form of 'warm feeling' from having followed relevant guidance & regulations on such things ... gas boilers may cost £700 from suppliers on the web, but that doesn't mean that they're not between £1k&£2k more when fitted ... the likes of Screwfix sell consumer units for around £60 but I'd doubt that you'd ring up a local electrician & get one supplied & fitted for much away from 10x that! ....

I could buy a battery unit and install it myself & look to have it signed off by someone for a small consideration too, but that's not the issue .... the point is that unlike yourself, myself & a number of others frequenting this thread recently, most people probably wouldn't consider the risk of not sourcing on a one-stop supply basis in order to receive the correct paperwork & some form of equipment & workmanship guarantee and it's this that I've referenced a couple of times now ....

Find an appropriate supplier that advertises a (national!) supply & professional installation price with all of the appropriate paperwork & relevant consumer guarantee and maybe we can discuss costs/kWh on the same comparative basis as installed prices of alternative brand equipment that have recently been mentioned ... if not we're not really considering on a like-for-like basis and therefore likely irrelevant for the majority of people ...

... But isn't this effectively what I've mentioned before?!


HTH
Z

zeupater

Solarchaser wrote: »

To be honest I think I covered what I said fairly well, that FOR ME the pylontech offered the best bang for buck, meaning as I added on modules that's what they would cost.
You are indeed correct I purchased an me3000sp and one battery, for £750, so FOR ME that still equates to £375/kWh.

However if i was to buy it new, instead of paying the £2250 that i paid, I'd now pay £3075
You may well have found ones for £3900, but who would pay that when you can get it from Ebay no less at £3075.
*turns out I cant post links*
So from that it would be (again using useable, not stated) £3075/6kw =£512/kWh.
I mounted no racks, the batteries sit on the floor under the wall mounted sofar, so no extra cost, still at £512/kWh.
Installation surely couldn't be more that £2-300 surely, so at the 6kw system maybe £562/kWh?

In comparison to the edf powervault offer of £600/kwh, which was already discounted by £2k, and although the powervault includes inverter, it replaces your own, so the fit would decrease.

Price of power walls, not sure tbh, but each time I've looked at them, no-one had any stock, so it was a non starter.

Pnp to me is positive negative positive, transistor
Plug and play is p&p

Hi


Effectively just answered this in post to 1961Nick above ...

Regarding PnP ... as you are probably already aware - it's almost universally accepted as a term related to automated device configuration .... you're starting to sound just like a rocket scientist would .... but obviously with a different accent! .... :rotfl:

HTH
Z

mmmmikey

The definitive answer to the PnP debate can be found here:

https://www.verywellmind.com/understanding-pnp-addictions-22360

PnP stands for "party and play." ..... "party" means to take illegal drugs, typically meth, and to "play" means to engage in high-risk sexual behaviors, including unprotected sex or group sex.

Good to be in a position where I can finally contribute something useful to this thread.....

onomatopoeia99

Solarchaser wrote: »

Price of power walls, not sure tbh, but each time I've looked at them, no-one had any stock, so it was a non starter.

Mine's due to be coming at the end of May, £7525 installed, which is £557/kWh. That's with the new gateway that continues to supply the house in the event of a mains failure. I think the new gateway pushed the price up by several hundred pounds from the original quote I had.

mmmmikey

Too embarassed to admit what I'm paying for PowerVault but you can find the details here!


https://www.edfenergy.com/for-home/battery-storage


The reason I went for this expensive option is that anything over 4kWh is wasted on me due to low consumption and the PowerVault has hardware and software support for frequency response grid services, which I'm gambling on being a significant factor in improving future economics and payback. Also really impressed with the company.

gefnew

Hi All
Found this on the web spreadsheet for solar batteries and inverter.
https://electrical-engineering-portal.com/download-center/electrical-software/calculate-size-of-solar-panel-battery-bank-inverter
regards

joefizz

Been away for a couple of days at the football in Liverpool and have 10 hours on a ferry to kill so will post a couple of perhaps long posts during the day.


As I said in my post a couple of days ago its better to try and think of all of this as a system and install, manage, investigate, address etc etc.


So one of the points in the last posts was about the sofar and its always exporting 200w and waiting for load to kick in and how that ties in with an induction hob (which I have).
The simplest thing I found to sort this out is to run a small load just before I started with the hob and then do the hob and then go back. All the discussion about kwp, joules, btus, adhds dont matter a jot when its as simple as turning a 250w load on. Now of course you have to find your 250w load and have to find one that benefits you and will work, for example a dishwasher or washing machine may not, an inductive load may not, a resistive load might actually work with var to reduce overall consumption but try as I might Ive never got that to work in the real world (much). Could be something as simple as setting laptop on to charge, or have someone watch tv when you cook or.. well thats down to the individual which was the whole point of my original post and and as others have said, down to your own behaviour within your system.



Its about changing behaviour. All this kerfuffle apart from misunderstandings of tecnical terms in the past is imho down to a basic misunderstanding of how your individual behaviour has to change to suit the 'system'. Yes, agreed that certain measures will only work to certain points (insulation, efficiences to get oil usage down) but its behaviour that modifies the rest.
To sort of cast up again for a minute a simple 'how did you manage to reverse 'normal' behaviour in electricity usage' would have prompted a more complex interesting set of responses that as others said to try and !!!! up the wall in a particular small pool.
Its only a very small proportion of human population that uses energy more in winter than summer when you think of energy as a concept.
For example (and dismiss real world examples as waffle if you like), up until fairly recently a lot of the west of ireland uses turf as solid fuel during winter. Now leaving aside the histories of blanket bogs and btus and inherent kwh for a minute, most people consider the energy expended as sticking the turf on the fire, in the range, in the boiler and setting light to it. Thats the end of the energy chain, what you dont see is the summer spent cutting the stuff, stacking it to dry in the wind and sun, gathering it up in large stacks and arranging so that water/rain runs off and then transporting it around to the houses in the locality where they then do the same in the turf store. Without the process of wind and sun during the summer there would be no winter heat.
My mate owns and lives on a eucalyptus forest off grid in chile. Simple you would think solar panels for summer, burn eucalyptus in winter.. well eucalyptus isnt great for burning and mcuh more valuable than pine for all sorts of stuff, so in the summer we used solar (I set the solar system up for them) to run equipment and other stuff (no getting away from fossil fuels for the harvesting) to sell and buy wood for the stove/heating etc in winter. I set up low energy lighting system for them so the solar will run that in winter and we used a couple of car batteries and inverter to run the laptop and cellphone chargers in winter and thats pretty much it. First time I met his wife, sitting a 5 hour bus ride south from Santiago, literally in the middle of nowhere, well water, no mains electricity for miles but with 3g cellphone coverage, she turns to me and says in spanish 'do you have facebook in your country'....
Anyway my point is that for millenia and in a great stretch of the planet the vast majority of people get buy with doing most of their heavy ,energy intensive work in Summer and just ticking over in Winter.
Anyone who has spent some time on the plains of Saskatchewan will know they go absolutely daft for everything in summer and in winter, well, theres ice hockey...
Saskatchewan winter was the coldest Ive ever been in my life and Ive been to the high arctic and Antarctica...


So what does this mean for me sitting in NI, well look at energy usage through the year and establish what your usual base load is and see if there is anything you can change to move it to the summer when with solar and battery energy is plentiful (24kwh yesterday according to my solaredge monitor so I left the dishwasher and the washing machine on timers whilst away in Liverpool).
We all have to wash, wash our clothes, wash our dishes, heat our houses, cook etc. So what do each of those mean in context.
Well washing, a few years ago I went to power shower only, just a pumped one using hot water from the tank. So hot water in the tank. I cant do anything at all in December given usual work load and its my worst month for solar so oil heating is needed. The oil heating also heats a full tank of hot water. I dont actually need a full tank of hot water for my usage, hence being able to use an immersion for most of the year for the shower and a dishhwasher and one inlet washing machine for the rest.
Im winter I have excess hot water so instead of using the dishwasher I just half fill the sink and wash the dishes that way. Just change behaviour. In money terms you might think this is ridiculous and most people do but thats what makes the difference. I regret not being able to replace my hot and cold water inlet washing machine with just a cold water inlet one. Although again just one inlet allowed me to move it to my studio and put a dishwasher in its place in the kitchen....

With the washing machine in the studio and very busy in summer and excess solar and occasional rain and not quite so high temperatures here in summer it made sense to get a tumble dryer to dry the clothes in summer. In fact when I spoke to the wholesalers they said in the last couple of years (not last year) tumble dryers were their number one seller in NI with kids off, wet or cold weather and so on...
So electrical energy increases in summer...
One of the drawbacks of putting in a filtered ventilation system in an almost passivehaus standard house was that for the first winter I got ill a bit and a series of sinus infections brought me to get some humidity meters. Id only ever previously got a sinus infection in Saskatchewan in the middle of winter (incredibly low humidity) and found out the new sealing in the house and not doing dishes in the sink and having quick showers and not drying clothes on the radiators meant household humidty levels were dropping to 35% during the night.

With the radiators on anyway with oil I got a few racks for the radiators and now dry clothes around the house (something my married mates said they wouldnt get away with).
Most other places in the world with low humidity thats a given, although you could just buy a humidifier and add to your winter electricity usage...


I looked at my cooking pattern, even with top rated oven, microwave and induction hob the majority of cooking was done in winter (comfort foods rather than salads etc).
So what do I mostly cook in winter? Well soups, stews, casseroles, curries, champ, cottage pies etc etc etc.
Nothing there I cant cook in bulk in summer/autumn, freeze in portion sizes and reheat in the microwave in winter. Certainly a lot healthier than ready meals or anything else. Increases electricity usage in summer/autumn, decreases it in winter. Of course you need somewhere to store this and buy a bigger freezer. Well 50 quid on gumtree for good quality older (less efficient, but again usually use the meals up by Jan as dec my busy period) large freezer, cheap slow cooker, cheap very large soup pot from ikea etc etc. Increasing electricity usage when its free, decreasing when its not.
Again if you just compare kwh and pounds in your pocket from that it probably seems like a waste of time, but when you add in eating healthier, decreasing carbon usage and the unseen ability to go and buy a sack of potatoes, carrots, onions etc from a farmer instead of a supermarket and over a period of weeks have a policy of eat one, freeze 6 or more then it all starts to add up (again drawing on various threads from different sections of this site and others into a 'system')
The huge box of mushrooms I buy I cant use them all so bought a cheap dehydrator and dried them all and ran it on the battery overnight... When I dried mushrooms I tried it on my raspberry harvest rather than freezing them. Those bananas, lemons, oranges that might go off get dehydrated now in summer or frozen...

People in this country have been doing this for millennia with picking, jams, preserving etc etc. Its why we have festivals like halloween, christmas, easter etc, celebrating times of plenty just before it gets hard. We just have better technology and different ways of doing things. It just takes a change of mindset and discipline, and in reality doesnt cost a lot of money if you follow a lot of the threads in other sections of this site and other similar sites.



Quick totally frivilous one, Ive mentioned before about the beer making, well its stouts and red ales for winter, light ales for the summer. Make them high enough alcohol content and they will easily keep for a year. I do the winter beers (halloween, christmas, easter specials) in the summer... ..you know where Im going with this... anyway, to serve properly you ideally want to be serving below 8c or even around 2c. That involves refrigeration if you want the perfect pint (most of my friends just want to get drunk so thats not really an issue).
Said extra freezer is set up as a beer cooler in summer so the 4 kegs go in it with taps. When the kegs get refilled with winter beers they get taken out and the freezer is filled with above food (and any cheap reductions in the supermarkets so in unhealthy areas of belfast you get trays of marked down seeded wholemeal bread, just the thing to unfreeze a couple of slices in the microwave in winter to have with your defrosted/heated soup). I live on the north side of a mountain so at the times I will be serving my beer, outside is at the ideal temperature or less, so an old whiskey barrel was converted to house the kegs, co2 and has taps attached. If I want a draught beer in winter I open the back door, go out on the patio and pour myself one... Of course I dont drink much so... anyway...
You can look at all of the above and dimiss it as nonsense, irrelevant, immaterial etc but thats what works for me, the individual reader has to work out what works for them.



Not everyone can do this, not everyone will do this, not everyone wants to do this but it is possible, particularly when you have seen other people in various parts of the world with a lot less resources than us and tailor their energy usage to when its most abundant its not hard to see where a battery system added to solar can start to make advantages. Some of the previous comments are about justification post event when I hope to show that all of the above was justification pre event. YMMV though and its an individual call.


Ive loads of other examples (growing own herbs now, growlights etc, then drying or freezing them) which in real terms just comparing like for like probably seem like more effort than the monetary outlay but I did mention fireing at 50 (this december) didnt I? ;-) and as others have mentioned I pretty much have a negligible electricity energy outlay per year (70 quid in December for that quarter) and will probably be less than 100 quid for 2019, despite using a lot more electrical energy than previous years. If the ASHP works out I might reduce my oil bill to around 600 litres per year which is my target. I could hit that target by wearing my antarctic gear around the house but it does make it hard to type and unzipping 6 layers just to have a pee no matter how high it goes up the wall, is just too big a stretch...