On-grid domestic battery storage

silverwhistle

zeupater wrote: »

if you think that that's low, there are a number on these boards that would disagree as we import even less ... we've not imported anywhere near 1500kWh since 2013!

1500 kWh? Profligacy! To reinforce Z's point mine is c.1130 kWh p.a..

zeupater

jcontest wrote: »

... We are a Gadget'y household and that doesn't help when it comes to power usage. Several Laptops, Router, Access Point, two switches, VoIP Hardware and all that jazz. Fridge, Oven, Hob, Washer, Dryer are all good on energy usage (Granted, Fridge is quite old so it might not be compared to newer stuff). Forgot to add in the Electric Shower too.

I did add it all up a few years ago and it's not far off of what it should be considering what we have on, but your correct in that it would be good to see exactly what's using what.

Hi

... but all of those gadgets and their usage pattern exactly describe why using consumption information derived from a smart-meter is pretty useless ...

Did you note the following inaccuracy in expected battery performance between actuals & HHM data timescales in the link provided yesterday? ...

................ 5 Minute ... HHM ..... Hourly
................ Actuals
Export .... 7.6kWh .... 6.0kWh .... 5.4kWh
Import .... 6.7kWh .... 5.1kWh .... 4.5kWh

... the conclusion being that over a single day, data at smart-meter collected intervals would overstate the energy to charge the battery by over 20% and the contribution of the battery towards imported energy savings by just under 24% ...

My thoughts are that the smart-metering project is unlikely to benefit the average bill payer & provides nothing useful to anyone who needs an information flow capable of being processed by a home BMS or EMS, whereas the same management systems with the same data frequency is extremely useful in business environments because of the diluting effect of scale on average usage ...

HTH
Z

jcontest

I'll be honest, I thought the SmartMeter spec allowed for data points MUCH more often. I actually thought the query was required to allow it to be as low as 10 seconds back to the operator. So half-hour readings would indeed be useless. I thought that the data upload might not happen as often, but that query points would be 10s or less. Fool on me I guess.


And I am not judging anyone, I am just a bit of an odd person in how I communicate with others! I personally don't think "now" is the time, but I also don't think adopting now would see you take any real losses. Again, a lot of consideration would need to be placed on what you by.


There's also the upshot of future grid problems being buffered by your battery system. The UK Grid is showing signs of strain and it's just a lack of under investment. Will that lead to blackouts/brownouts? Another wild guess sadly. But that's also worth considering.


I'll look at the RasPi solutions. Thought of trying it out in the past but never did take the jump. Tried to get the kids to do it for me (learning and free labor!) but that never happened.

zeupater

jcontest wrote: »

I'll be honest, I thought the SmartMeter spec allowed for data points MUCH more often. I actually thought the query was required to allow it to be as low as 10 seconds back to the operator. So half-hour readings would indeed be useless. I thought that the data upload might not happen as often, but that query points would be 10s or less. Fool on me I guess.


And I am not judging anyone, I am just a bit of an odd person in how I communicate with others! I personally don't think "now" is the time, but I also don't think adopting now would see you take any real losses. Again, a lot of consideration would need to be placed on what you by.


There's also the upshot of future grid problems being buffered by your battery system. The UK Grid is showing signs of strain and it's just a lack of under investment. Will that lead to blackouts/brownouts? Another wild guess sadly. But that's also worth considering.


I'll look at the RasPi solutions. Thought of trying it out in the past but never did take the jump. Tried to get the kids to do it for me (learning and free labor!) but that never happened.

Hi

The issue isn't the reading interval, it's the frequency at which the information is written for retrieval.

It's likely that the higher available frequency you're thinking about is that at which the smart-meter communicates with other devices on the HAN, so initially between the master (electricity) and additional (gas) meters as well at to the IHD.

The specification theoretically allows for devices such as PCs or dedicated management control systems to access this streaming data directly, but the industry now seems to have a worry about allowing users to configure & add devices ... even IHDs if necessary.

If direct access to the smart-meter is available via (say) a PC, the SMETS2 spec allows for both push or pull data delivery ... if you want to periodically download data you'll be limited to pre-stored historic HHM values and, from memory, be limited to the previous 3 months to date ... if you want to receive & process pushed data then you need dedicated HAN attached equipment to be available at all times to receive the transmission, or it's simply lost ... the last time I read the spec it seemed that the maximum push frequency could be set to multiple times per second (10?), but that would obviously impact on battery life and possibly the ability to communicate with the IHD too, providing the industry with a reason to not allow anyone other than themselves to allow this level of user controllability ... I recall that the default IHD update frequency is 10 seconds for electricity & 30 minutes for gas as a battery saving measure (which would be absolutely useless to an EMS for DHW temperature top-up!) ...

Regarding battery buffering for grid issues ... this is possible, but you need the ability for the entire home to automatically disconnect from the grid & operate in 'islanding' mode (which includes AC grid frequency simulation for the PV inverter & battery solution to synchronise to), this being to ensure that no generated or stored energy can enter the grid & cause harm to anyone working on lines & equipment assumed to have no power! ... so additional cost to consider if you really need the option.

You must understand, myself & others posting on this thread are really interested in battery solutions to supplement our own PV systems, there are even some that have accepted the economics of being an early adopter and already have batteries in place, but the general consensus is that they're simply too expensive to warrant serious consideration at the moment, therefore we simply try to help others understand the underlying issues and how a realistic approach to justification needs to be applied .

My own view (supported by many others) is that there's a tipping point at which consumer demand will start to seriously kick-in ... unfortunately, even systems currently at the lower end of the storage price band (£/kWh) are around 3x higher than where they need to be to stimulate demand and more likely 4x more than where they need to be to really compete against grid-supplied energy ...


HTH
Z

orrery

zeupater wrote: »

My own view (supported by many others) is that there's a tipping point at which consumer demand will start to seriously kick-in ... unfortunately, even systems currently at the lower end of the storage price band (£/kWh) are around 3x higher than where they need to be to stimulate demand and more likely 4x more than where they need to be to really compete against grid-supplied energy ...

But, fear not - prices will drop:
https://cleantechnica.com/2019/03/31/global-lithium-ion-battery-planned-capacity-grows-4-in-a-single-month-charts/

Martyn1981

zeupater wrote: »

Regarding the hybrid panels raised earlier ... I gave these some thought a few years ago & couldn't see how they could divert high enough temperatures to DHW without either decreasing the efficiency of the PV generation through insulating a module (which would be essential for the majority of the year), or requiring the majority of the DHW heating to be performed by PV generation proportional diversion ... our PV panels are currently around 30C, but the bottom of our DHW cylinder is higher so uninsulated hybrid panels wouldn't be helping at all, whilst later today insulated hybrid units would need to be operating at around 70C(+) to raise the stored water temperature to reasonable levels without using electricity ...

HTH
Z

Here's a thought, and it is a bit out there, but in the US heat pump water heaters are getting a lot of good press. they will cost perhaps $1k more to buy, but are around $300-$400 pa cheaper to operate.

Now, these work well where the water heater has access to outside air, such as a garage, or perhaps a semi-vented basement. But also work excellently in states where heating is only needed for 1 or 2 months a year, so the cooling effect is a benefit, even if within the structural envelope.

OK, so, so far that's irrelevant to us, but, what if the HP water heater operated via a heat-exchanger and a small water tank connected to the hybrid PV panels. This way the panel water heat doesn't need to be high, in fact it could be run cold to cool the panels.

1. Does any of that make sense? If yes, go to 2.
2. Do you think it would make economical sense?

Martyn1981

jcontest wrote: »

And I am not judging anyone, I am just a bit of an odd person in how I communicate with others! I personally don't think "now" is the time, but I also don't think adopting now would see you take any real losses. Again, a lot of consideration would need to be placed on what you by.

No problem mate, and no-one is more odd than I, and in being overly defensive, I'll often appear overly offensive.

Just like Z, and many others chatting on here, and clearly yourself too, I really want a battery. I want to play with it, stroke it affectionately and give it a name. And whilst I'm not a 'stick it to the man' sort of person, as I appreciate the need for national generation, transmission and leccy suppliers, I'd really like to see just how low I can get my import ...... an oddity I suspect is shared by many.

Personally I'm completely torn regarding early adoption. I cheer those that have jumped, and will cheer on anyone that follows, but I'm just not ready yet, and prefer to invest in renewable schemes until the economics of batteries improve a bit, or additional income streams mature, such as peak rate (price) sales to support high demand periods.

Again, personally, I don't think there is any issue with the grid's ability to absorb all RE gen at the moment, so I'm happy to use economic arguments to settle my current decision quandary, but am keeping an eye on the environmental side, though I suspect environment and economic issue will come together nicely in a few years time as the domestic stationary energy storage market matures.

All the best and keep on pondering, I love a good ponder on here. :think:

zeupater

Martyn1981 wrote: »

Here's a thought, and it is a bit out there, but in the US heat pump water heaters are getting a lot of good press. they will cost perhaps $1k more to buy, but are around $300-$400 pa cheaper to operate.

Now, these work well where the water heater has access to outside air, such as a garage, or perhaps a semi-vented basement. But also work excellently in states where heating is only needed for 1 or 2 months a year, so the cooling effect is a benefit, even if within the structural envelope.

OK, so, so far that's irrelevant to us, but, what if the HP water heater operated via a heat-exchanger and a small water tank connected to the hybrid PV panels. This way the panel water heat doesn't need to be high, in fact it could be run cold to cool the panels.

1. Does any of that make sense? If yes, go to 2.
2. Do you think it would make economical sense?

Hi

We actually considered a unit to do this when the PV went in, not to cool the panels at the time (although the idea did occur at the time if a suitable unit was available!), but to just heat the water ... decided that the figures didn't stack up though after digging deeper into the performance specs and recalculating the savings based on including PV self consumption as opposed to purchasing all electricity as we were doing at the time ....

The savings you reference are also likely to be pre-PV based and therefore highly inflated, so the question simply comes back to available roof space ... and of course, the additional cost & benefit of having & installing hybrid panels to capture the heat ...

I like the idea, but doubt the economics of such a setup would really stack up ... it's far too close to the refrigerant based thermal panel heating systems pushed on these boards around 5 years ago to not be able to form an initial opinion on ... open to discussion if anyone's made a major technical advancement which conforms to various laws of physics and is relatively cheap, efficient & maintenance free compared to PV panels in unusual places/positions, but ....


HTH
Z

1961Nick

zeupater wrote: »

My own view (supported by many others) is that there's a tipping point at which consumer demand will start to seriously kick-in ... unfortunately, even systems currently at the lower end of the storage price band (£/kWh) are around 3x higher than where they need to be to stimulate demand and more likely 4x more than where they need to be to really compete against grid-supplied energy ...


HTH
Z

Is the tipping point really that high?

My 12kWh system cost £4520. If you halved that I reckon there would be a lot of interest as ROC would be well under 10 years for most people.

A hidden saving with storage is that you no longer waste surplus energy during the day. For example, little things like putting the PC to sleep rather than leaving it on start to add up.

At what point will you make the jump?

zeupater

1961Nick wrote: »

Is the tipping point really that high?

My 12kWh system cost £4520. If you halved that I reckon there would be a lot of interest as ROC would be well under 10 years for most people.

A hidden saving with storage is that you no longer waste surplus energy during the day. For example, little things like putting the PC to sleep rather than leaving it on start to add up.

At what point will you make the jump?

Hi

Is that 12kWh useable or gross and did it include installation, energy management ancillary equipment & VAT? ... anyway, for a complex issue I'll attempt to simplify the tipping point position without referencing performance models ....

I'd tend to look at the manufacturers net maximum capacity as they often lock out a proportion to help with lifespan, efficiencies etc .... for example, of a Powerwall2's 14kWh of batteries, only 13.5kWh is really accessible ... from what I've seen there's no particular standard that manufacturers follow to allow consumers to compare offerings ....

If your price is fully installed it looks like around 2.5x higher than the likely tipping point, which is probably somewhere around £150/kWh, which shouldn't be too hard to reach with battery packs currently trading at an average price below this already, (Average 2018 was supposedly around $175/kWh & expected to fall to below $95 within 5years) with some considerably cheaper, notably this is at volumes which are considerably lower than a major purchaser would be taking ... Tesla for example are already producing their own batteries at, or below, $100/kWh, which is probably somewhere around double the theoretical minimum cost for current cell capacities & technologies.

So, £150/kWh would place a Powerwall2 at somewhere around £2100 (~$2750) of which the current cell cost makes up around 50% ($1400) but is falling fast.

A user with PV resulting in (say) 1500kWh of remaining electricity imports would have a saving ceiling of around £225/year (1500*.15) if all of the energy could be delivered from battery stored PV generation. This in itself would equate to around a 10 year payback on a PW2 even at £2100, but with a typical array of 4kWp there would still need to be considerable imports, so we're starting to rely on equipment & storage lifespans considerably longer than typical design & test specifications would consider .... anything over £150/kWh just makes the calculation results & timespans worse!

HTH
Z