On-grid domestic battery storage

joefizz

1961Nick wrote: »

An ASHP with an eco setting will do a reasonable job of avoiding 'peaks'.

Our heat pump tumble drier appears to have a lower peak demand than the old one.

I've installed a boiling water tap to avoid the 3kWh kettle load. A 1, 1.5 or 2kWh kettle would do the job but take an age to boil.

Cordless power tools, hoovers, mowers etc, enable you to schedule charging & avoid any load when there is little solar & the batteries are empty.

Avoid the 12kWh induction hob!!!:eek:......but it keeps her happy.:)

Like all of the above, its about changing how you do things as well as the equipment. battery powered stuff takes the load off or evens it out.
Ive some low powered items for the campervan that can be run off small electrics (like kettle, microwave etc) but they take an absolute age but the kettle I think is 700w, so like old computers where you turned them on and went to make a cup of tea before putting your login details in, you have to plan ahead ;-)


Its what I mentioned earlier on in the thread, sometimes to save yourself energy you have to increase your energy usage. One of my dishwasher settings takes nearly 3 hours and uses more electricity than the eco setting but keeps the peak under the ambient plus battery supply, similarly with my washing machine and I think tumble drier. I can set those modes on and be sure I have enough for the kettle etc.
I ended up going with the one touch one cup kettle for the majority of it so its short bursts, so while the coffee/tea is brewing its time to turn the toaster on.. Or simple things like microwaving frozen bread to thaw then toast rather than using the frozen bread setting on the toaster.


The slow cooker has been a revelation as has stuff like the rice cooker, instead of boiling water, you have a smaller less energy required but for longer piece of equipment. So you can run other stuff at the same time or cook then use the keep warm facilities...


It goes back to some of my points about utilising the battery more and not considering it as a one charge per day cycle and if possible spreading the load over more time to get the same effect, which conversely for an eco friendly discussion actually increases usage but as the increase in usage comes from solar/battery then its not an increase from the grid.


Taking it a step further, again requiring a step change in behaviour and depending on your circumstances its possible to time shift annual loads so about this time of year I start using the slow cooker every day to make curries, stews, soups etc then parcel them up and freeze them for during the winter months.
I make home made pizza (electric pizza stone, garden wood pizza oven) so will do a lot of dough and freeze it along with selected cheeses toppings in portions so can pretty much defrost and have pizza over winter, saving money, time and diesel...
I also so home brew so did a couple of double brew days last week before I came away this week, knowing I could run the battery down to zero as Id be away and it would charge up despite the rain! Ive about 60 litres of beer to sort out when I get home and may do that another couple of times before the end of September. Halloween and Christmas party beers were put down last week, just have to do some general stuff and that should do me until the sun starts shining again properly in about April.


If its going to be sunny the next day, schedule the dishwasher/washing machine/slow cooker overnight to run the battery down, comparing with previous usages although Ive been away a lot and usually have the computers running all night every night going through the automated patches of my work so I can start afresh each morning (plus the heat generated makes sure I dont need any heating at all now during most of the summer). Ive only managed to get the battery down to about 21% once overnight this summer (9.6kW nominal) so more work on that required to make it a regular thing ;-)


Starting to consider looking around for a couple of 2nd hand solar panels I can just install for winter at low angle in the garden to add to december but it probably makes no financial sense at all unless I can get them free ;-)

Martyn1981

joefizz wrote: »

It goes back to some of my points about utilising the battery more and not considering it as a one charge per day cycle and if possible spreading the load over more time to get the same effect, which conversely for an eco friendly discussion actually increases usage but as the increase in usage comes from solar/battery then its not an increase from the grid.

Just sharing good news, but a few years back I asked 'the experts' on Navitron about small battery cycles, basically what you are describing. i was kinda asking if lots of small cycles added up to the same 'damage/wear' as a bigger cycle. Hard to explain, but let's say 10 5% discharges and charges, v's a 50% discharge/charge cycle, and the consensus of opinion was a solid NO they do little to no damage/wear.

So having a batt smooth out the peaks and troughs of PV generation v's the peaks and troughs of domestic demand through the day (providing a top up, or storing a bit of excess) is light duty for them.

Hope that's all true and helpful. Plus it spawned a nickname of Mart's micro cycles, as it's not the easiest thing to describe.

orrery

Martyn1981 wrote: »

So having a batt smooth out the peaks and troughs of PV generation v's the peaks and troughs of domestic demand ...

I've become more and more convinced that a cheap system with a small battery, provided it can supply more than 2kW and can charge at the same rate, would be cost effective as I can see a huge amount of power wasted by PV fluctuations during the day.


e.g. I'm generating 500w more than I need (exporting it for free), then suddenly the washing machine turns its heater on and uses 2kW for 10 minutes which I import and pay for. Of course, the immersion diverter uses the excess export, up to a point, but as it is displacing gas it isn't an economical usage (environmental, yes).

mmmmikey

orrery wrote: »

I've become more and more convinced that a cheap system with a small battery, provided it can supply more than 2kW and can charge at the same rate, would be cost effective as I can see a huge amount of power wasted by PV fluctuations during the day.

That's exactly the conclusion I've come to from the experience of using a 4kWh battery with a 4kWp solar array over the last few months. It's quite notable how much better you can utilise the solar panels during the sunshine hours with even a small battery to smooth out the peaks and troughs, particularly during the sunshine and showers weather we've had recently.

1961Nick

orrery wrote: »

I've become more and more convinced that a cheap system with a small battery, provided it can supply more than 2kW and can charge at the same rate, would be cost effective as I can see a huge amount of power wasted by PV fluctuations during the day.


e.g. I'm generating 500w more than I need (exporting it for free), then suddenly the washing machine turns its heater on and uses 2kW for 10 minutes which I import and pay for. Of course, the immersion diverter uses the excess export, up to a point, but as it is displacing gas it isn't an economical usage (environmental, yes).

The sweet spot very much depends on your circumstances. Ironing out all the generation peaks & troughs with a small battery installation is a big plus, but then you have to apportion the capital cost of the inverter & installation to that one battery & it’s a long stretch to get your money back. Conversely, making the installation too big means the last battery is only effectively contributing on exceptional days.

Martyn1981

orrery wrote: »

I've become more and more convinced that a cheap system with a small battery, provided it can supply more than 2kW and can charge at the same rate, would be cost effective as I can see a huge amount of power wasted by PV fluctuations during the day.


e.g. I'm generating 500w more than I need (exporting it for free), then suddenly the washing machine turns its heater on and uses 2kW for 10 minutes which I import and pay for. Of course, the immersion diverter uses the excess export, up to a point, but as it is displacing gas it isn't an economical usage (environmental, yes).

That's one of the things holding me back on getting a battery, there are also several thousand other reasons all starting with a £.

My original plan (sorry to repeat old posts, but they are now very old) was for 4kWh useable of battery capacity, since I only import about 2.5kWh per day in the summer, and only export a few KWh's in the winter. The main benefit would be the shoulder months with import around 5kWh, which a 4kWh battery should cover assuming some of that is 'Mart mini cycles' through the day.

But, then I started to ponder, something I do far too much of, and thought about an all in solution for the future, PV, batts, BEV & E7.

Our driving is small to average, one car, 8,000 miles pa. So if I add about 1.2kWp of south facing steep pitch panels (ground mount) and get a 10kWh+ battery, then I'd have enough spare batt leccy to charge the car for six months of the year, with E7 covering the other 6 months, and the daytime PV + batts providing extra ASHP heating in the shoulder months (less import), and E7 + batts in the wintertime.

I think it all makes sense, but outside of my financials at the moment, and costs should fall further, and I might ponder it all away again.

Martyn1981

Or I could wait and hope for WPD (my DNO) to include me in a virtual power scheme. Well, one can dream!

Nothing Succeeds Like Success — Tesla Virtual Power Plant In South Australia Could Expand To 50,000 Homes

South Australia, whose capital city is Adelaide, agreed to participate in a virtual power plant program sponsored by Tesla last year. The first phase of the experiment installed rooftop solar systems on just over 1,000 low-income houses and coupled them with Tesla Powerwall home storage batteries. A second phase earlier this year added about 300 more homes to the test population. The batteries store electricity during the day to help power the homes at night. In addition, all the batteries are linked together digitally so that some of that stored electricity can be fed back into the grid to meet peaks in demand or provide power during an outage.

The fossil fuel lunatics went crazy when the virtual power plant idea was proposed, dredging up a million and one reasons why it wouldn’t work. They were wrong. It worked better than anyone dared hope. Now that the first and second phases of the trial are over, the data show that the people who are participating in the pilot program are paying about 20% less for their electricity than their neighbors. Take that, Scott Morrison!

Martyn1981

Here's another VPP (virtual power plant) with 600 new properties all having 20kWh batts.

sonnen & Wasatch Group Launch Largest Residential Virtual Power Plant — 12.6 MWh

A new community of apartments in Herriman, Utah is being built from the ground up with a next generation energy storage system thanks to 12.6 megawatt-hours of sonnen’s ecoLinx battery systems. The new system will aggregate the energy storage and power output capabilities of 600 of sonnen’s 20 kWh ecoLinx intelligent energy storage units installed across the community into a single virtual power plant.

Zarch

Moxia pushing their summer battery sale via email (ends 2nd Sept)

4.8kWh £3,950
3.0kWh £2,950
2.0kWh £2,450

Prices include VAT and installation costs.

In comparison, 4.8kWh Sofar/Pylontech combo is £2,450 (fitting extra)

https://www.ebay.co.uk/itm/PRICE-SLASHED-Sofar-Solar-Mass-Energy-ME3000SP-Solar-Battery-Storage-4-8Kwh/233226349610?hash=item364d5fac2a:g:LocAAOSw9idZ72Tz

A justifiable comparison?

Solarchaser

I'd say the sofar and 4.8 pylontech at £2,271 also on ebay is a better comparison, meaning for the same price as the moxia 4.8, you could have a sofar with 9.6kwh.... but that's still not installed.

I'd argue the installation of a sofar is pretty darned easy... but then so is everything if you know what you are doing... and many dont.

I cant comment on the moxia, as I've sofar (get it ) only tried the sofar.

If you were to get the sofar I'd recommend 3 batteries as a minimum (7.2kwh) as this let's it do the 3kw charge and discharge.

The big problem with batteries is once you have some, you want more... and you want bigger charge and discharge.
The lux does 3.6kw charge and discharge.
Parralel lux does 7.2kw... or 10.8 etc etc

The biggest problem with batteries is it turns you into even more of an anorak than you ever thought possible:(