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Author Topic: Are batteries worth it, does this calculation work?  (Read 7793 times)
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« Reply #15 on: September 18, 2018, 09:34:05 PM »

Its financially worth it if you can get second hand gear cheap enough. My repurposed growatt lithium batteries have worked out cheaper than my lead acid forklift batteries which have worked out at pretty much cost neutral. Also all my renewable gear has been purchased with borrowed money at cheap rates, all being paid back with my FIT income so its all free anyway. By the end of my FIT period I could put everything in the bin and I will have lost nothing but still had lower elecy bills for 25 years. fingers crossed!

Its technically worth it if you like tinkering / experimenting and seeing how low your import can go. My import for a 4 bed family home is now down to 0.15kWh per day Feb to Oct. extrahappy

Its amusingly worth it when your street has a power cut and you open your curtains and turn on every light in the house. Done this a couple of times. stir

It will be increasingly worth it as we move to time of use tariffs which is the only way we are going to have enough peak generating capacity for all these EVs and heatpumps. My house is fully TOU ready now. bike

Its environmentally worth it if you like reducing your CO2 levels. In this case doubly worth it cos you will also have forgone a long haul holiday, a hot tub or other CO2 intensive thing. I donít see myself as an Eco Warrior but I donít like waste. fight

There are probably many more reasons to have batteries (obvious one being off grid), but the above are relevant to me. Cool

12kW+ of PV installed and 60+ MWh's generated.
Home battery storage of 40+ kWh's.
Hot water storage of 15+ kWh's.
Heat storage of 15+ kWh's.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
290,000+ litres of water harvested from underground river.
« Reply #16 on: September 18, 2018, 10:41:45 PM »

For laptops and mobiles, there is sod-all to very little,

Wholeheartedly disgree. There is cell/battery mismanagement. Big business; "non-replaceable" componentry & manufactured obsolescence.
The last two phones I had reach 4.1V at 75% charge. 4.35V @ 100%
Makita tool batteries will never take a recharge if you lose power to the BMS or drop them below threshold. Samsung laptops do this too so it is extremely difficult to recell them.
Some laptops have cycle counters and electronically controlled diminishing returns.
Smapple just cook theirs with deliberate oversight on thermal management.

If you root access androids you can confine the charge & discharge thresholds.

50% bigger phone cell with same extracted energy per cycle = 6 times the lifetime cycles.
We ought to stop voting for slimmer devices with our wallets.

Careful what you buy because every time you do you say that's an acceptable product.
If it can't play nice with other manufacturers' equipment then as far as I'm concerned they can go attempt procreation with their headwear.
« Reply #17 on: September 18, 2018, 10:53:42 PM »

Its financially worth it if you can get second hand gear cheap enough.

Sounds like every piece of power electronics I own.
I've only paid for 4 outtov my nigh 20 batteries.  whistlie

Its amusingly worth it when your street has a power cut and you open your curtains and turn on every light in the house. Done this a couple of times. stir

Ah yes this is my favourite. When trade sparkies tell me solar is unreliable and I point out I haven't had a powercut for 8 years and my motorhome can power buildings.  Tongue

Remote powah to sheds and sites are another good application.
Cabins in ja woods.

I donít see myself as an Eco Warrior but I donít like waste. fight

Second that.

There are probably many more reasons to have batteries

Wireless powah! Because Tesla (Nikola, not the neo-antithesis) Coils are too expensive and complicated.
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« Reply #18 on: September 19, 2018, 09:03:57 AM »

I was importing 25kWh a day on average and now I do less than 1500kWh a year. Our meters haven't increased since the end of February and opefully our grid consumption will go down with the use of a wind turbine during the winter. I'm just in the process of making the mast. We also now have a heated pool for the kids.

I agree with nowty but it's not for everyone. I do it because it gives me great pleasure.

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
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« Reply #19 on: September 19, 2018, 10:38:59 AM »

Holes in the roof? WhaaaaT?
Nah! Hydrocaps!

Is hydrogen release a problem with the lead acid these days.  Should I have them in a shed out with the main building?

6.48kw Solar PV JA (300W)Panels, SolarEdge inverter
Borehole -> Nibe F1255 12kw GSHP -> Radiators
Nissan Leaf
« Reply #20 on: September 19, 2018, 10:43:48 AM »

Not especially. Depends on how big the battery is & how aggressive the charger is. You can vent it, recombine it or ignore it. Just try not to contain it (extremely difficult) and ignite it.
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« Reply #21 on: September 19, 2018, 12:35:32 PM »

"Are batteries worth it", Depends if your only interest is financial to be honest.

I installed batteries without too much regard for "will they ever pay for themselves", my motives are as followed:
  • I am earning more money now that i am likely to earn later as i get older (55 so retirement is only 10 years or so away)
  • I wanted to use some of the spare cash i earn now to offset my reduced income as i get older and or retire giving me more free cash for fishing and boating stuff
  • I despise giving so much of my money to the utility services that are ripping everyone off (batteries allow me to hand over less cash for many, many years)
  • I wanted to be greener or more kind to the environment by using more of my home generated juice
  • I wanted a backup system that will keep my 360 LTR fish tank warm and my fish alive in the event of a power cut
  • I will definitely get a better return on my batteries over decades than i will from my company pension as they force closed the scheme last year
  • FITS gives me money every month for more assumed export than i have used myself, where previously they gave me less money than the amount i was exporting, this pleases me Smiley  

I guess like many i hope they will pay for themselves, but if they don't, i dont care as they are now bought and paid for so in my mind they are now saving money every month and will continue to do so for years, and i would only have thrown that money away of motorbikes, cars of fishing rods, this way i am a little better off each month.
« Last Edit: September 19, 2018, 12:37:12 PM by Sprinter » Logged
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« Reply #22 on: September 19, 2018, 04:34:12 PM »

Interesting discussion, thanks chaps.

I'm a bit of an eco-warrior - wife says we don't get invited to dinner anymore because I spend the whole evening haranguing my range-rover-school-run-driving hosts ...

Although I'm changing my tune from using absolutely minimum energy to having comfort, and producing/storing my own energy so that I don't consider extravagant use to be "waste", because I hate waste with avegence.

"Why did you leave that light on? How am I suppose to get the energy it used back in the bottle?"
"Chill Dad, the Roof made that energy ..."

A conversation on here a few months back (sorry, forgotten who with) changed my mind from night-venting to cool our Passive House on hot summer days to installing reversible heat pump to put cold water through UFH to cool the floor instead (and by not opening the windows also not let the flies in ... and also not have the day temperature creep up to 25C in a mega-heatwave which is a tad hot if you are just sitting still and don't have a fan on)

Insulate ... Insulate ... Insulate

Done that, but I started with reduce ... reduce ... reduce ... I read the meters and measured the oil-tank each week, and made a graph. We cut our electricity use by 50% and our oil by something significant, and then switched to biomass. That switch cost a fortune .... but oil price (unexpectedly) shot up and all my mates who originally thought I was several Prawns short of a Barbie were jealous and asked about my crystal ball.

The Tesla purchase was 3x what we normally spend on a car. Brexit then caused the pound to cave, and two years on the car is worth close to what I paid for it ... and driving is less than 3p a mile for Fuel and saving me £4,500 a year on fuel (27K miles p.a.)

So Lady Luck has sponsored my Eco Follies.

But ... I'm knocking on a bit ... removing variability from my fuel costs, by spending on Capital now, has appeal for my retirement and being able to retain both my lifestyle but also not becoming old and in a cold, draughty, damp house.

I too want to be 100% "Time-of-Use Tariff Ready" and take advantage of that.

If power company is happy to pay me on assumed 50% export of my PV I'd be a mug not to export zero units or not to install the maximum amount of PV that they will let me grid-tie.

If I'm going to get a battery I will have to buy PV too (maybe only a 1ft square panel?!) to get the reduced VAT ... and I want to do that before next spring before the FITs go away.

Physiologists said BEVs owners have better karma when driving. They couldn't figure out why; maybe because BEVs are quiet, or maybe because owners are pleased to be doing their bit. So if ECO-SMUG is going to make me feel better then I need more PV, more Battery, more Heatpumps ...

Lots of reasons to do it, but mostly because it seems to have worked out alright for me, despite the what the maths said at the time.
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« Reply #23 on: September 19, 2018, 08:09:16 PM »

Batterries just helped me to get more independant , i jus dislike the fact of beeing controlled ,  not thinking allways aboutz dollars  , was and is worth while the studdy , and my battery is 15 years old now 

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
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« Reply #24 on: September 20, 2018, 12:21:12 AM »

I haven enjoyed reading this thread and the views on the subject.

My old deal with power company a couple of years ago was 8.6p then 13.4p then 15.8p and is now 16.34p fixed until 2020. That is all the financial justification i needed to make to myself.

I like the independence, I like the clean power, i enjoy the added PV efficiency of use of our own power that the batteries give.

I like the battery graphs which have allowed me to see the massive burn rate of our 4 fridge & freezer units. This will be addressed.

I like the idea that i can add to the system and disconnect further from the grid if i choose to and conditions allow.

Great to read of others and the reduce aspect due to raised awareness and also the 'chill' element once been out there to the extreme.

There is a non quantified value in knowing that as you age you will not be at the mercy of rising prices but will instead be sitting on your holidays while your home ticks over at no cost and earns, That thought is priceless.

Some of the above are intangibles but only in money terms, the value is still there and can be felt every day. A part of me thinks it mildly strange that so much focus is brought to bear on the returning of cost at the pounds and pence end, that focus misses quite a lot of the benefits.

An example, I'd love to think i could install a low cost heater in a polytunnel running off the batteries and go chill there in the Winter months.
« Last Edit: September 20, 2018, 01:16:12 AM by pantsmachine » Logged

5.12kWh PV system with Solar edge
7.2kWh Pylon tech battery storage
18kWh Heater Storage
Solar I boost charging 12kWh 210 ltr OSO system tank
Deep insulation, air leak controlled home
Zoned & Balanced CH wet system
Hive 2
Low energy bulbs
24 kW Leaf
Masanobu Fukuoka garden & wooden hot tub
« Reply #25 on: September 20, 2018, 12:54:10 AM »

1kWh for campervans from a campsite socket is between Ä3 & Ä5 in …ire. Another Ä25 for the pleasure of parking beside the outlet.
60 cell solar panel payback = 4 nights.  bike
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« Reply #26 on: September 20, 2018, 07:49:46 AM »

where we live most people heat water with electric and heat odd rooms with electric in the winter supplemented with a wood stove or fire.
my next door neighbor does this and spends Ä2200 on electric a year.
so was our initial investment and updates been worth it? well no EDF bill for 7 years and the thought of not having a big bill on the way is great, we do use red diesel to charge in winter but the usage is dropping and cost is negligible.

would i recommend it? is it worth it? as a lot have said above if you like tinkering then yes if not, i think no.


1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
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« Reply #27 on: September 20, 2018, 11:56:00 AM »

I applaud anyone trying to distance themselves from the corporate grid structure but the sobering fact is that we are all intrinsically tied to it by virtue of our lifestyles - even us off-gridders whose numbers are sadly limited by means and circumstance. True eco -warriors are hard to find.

I am unconvinced by the merits of domestic grid-tie batteries on all levels. I perceive the current raised profile to be driven primarily by consumer sales interests and the all pervasive obsession with "new tech". The possibility of having such a thing is, after all, not exactly new. I think enthusiasm, time, money and effort would be better spent pressing for a rational, sustainable and equitable national grid structure rather than adding more layers of stuff and complexity at the domestic level.

That said I am interested to hear about the performance of the alternatives to FLA batteries - the emphasis here being on real world data and not lab testing or agenda based evidence trawled off the web. Trouble is this information will only be useful many years hence and probably beyond my active interest. The other perennial problem is that real world experience from battery owners is traditionally often economical with the truth about the circumstances of use. Apparently most FLA (even s/h) installations live longer than even the manufacturers wildest dreams! This may not be untrue - probably depends how they are used, but this is either a bit of a secret or not really known. Things do not look like changing much as within this thread alone there are several different and selective descriptions of performance, none of which tell me much I could rely on to make a decision.

There was a time the first piece of simple advice offered to anyone wanting to detach themselves from the grid was to fully understand their generation patterns and consumption needs, reduce consumption to what is actually necessary and then determine the best installation. Seems this fundamental first step is in danger of being skipped in favour of  "I must have a domestic battery - now how can I go about justifying it". Perhaps a bit more in-depth monitoring and then some simple time shifting of consumption might be a better starting point for most people - loads of options available at little or no cost to achieve this.

I have only one reason for having a battery bank - if I didn't the lights would go out unless I clocked up a financially unacceptable number of generator hours. I have no love of the battery bank - it is the single most expensive renewable energy item I have, it produces nothing and consumes a fair bit, buys a variable and unpredictable amount of autonomy, it's longevity is an unknown and when it does give up the ghost I will probably need to spend a similarly large amount again to replace it. The battery is necessary for an uninterruptable off-grid set-up with sustainable pretensions, if I were connected I think it would simply be another gadget.

Although I am not enamoured of my FLA battery bank I don't really understand where all the talk of them being hard work and a lurking hazard comes from. I spend little time actually doing anything with mine - 10-15 minutes water top up and general faffing about every 4-6 weeks. Sure I monitor it's status and have poked around with some charge control settings but the attraction soon wanes unless you start inventing reasons for more fiddling. I can't imagine what extra excitement there would be in having a Lithium fit-and-forget box under the stairs. With no proven track record I think the Lithium would worry me a bit more.

I'm sure there are people with real and genuine reasons for wanting a grid-tie battery as in some of the above posts. Interesting that the justification seems to have whittled down from some less than clear financial  reasoning to mostly a feel good thing. Nothing wrong with that as a personal choice and certainly more credible. Can't see why the general populace would want one though - only a tiny proportion have PV and that was a financial no-brainer with uncontrived green credentials. Probably going to remain a niche item for the foreseeable then (with all that entails) despite the best efforts of the "renewable industry" PR machine and acolytes to kick start it up the ladder.

I say an unashamedly self-interested "good luck" to all those Lithium enthusiasts and look forward to future objective reports regarding the performance of their batteries in whatever circumstances they are used - won't hold my breath on the objective bit though.

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
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« Reply #28 on: September 20, 2018, 02:28:43 PM »

I am unconvinced by the merits of domestic grid-tie batteries on all levels. I perceive the current raised profile to be driven primarily by consumer sales interests and the all pervasive obsession with "new tech".

I share your view, but speaking for myself:

I work from home, my wife too on occasion, and a couple of other (office folk) work from-here too.  We also have servers that are accessed from remote. A power cut is a PITA on two counts - firstly that any work-in-progress is lost (except where we have individual UPS, but they are without exception cheap-and-cheerful and fail sufficiently often to be almost as bad as the power cuts themselves) and secondly from the loss of remote accessibility.

A whole house backup battery would be great, but even one that tripped (to disconnect from the grid) and then allowed continued working would be sufficient.

PowerCuts here are frequent (at least once a month) and normally last a few seconds, sometimes a few minutes, and once or twice a year for a few hours (e.g. JCB dug through the cable). Scheduled downtime is probably a once or twice a year thing - e.g. cutting overhanging branches

So I have "lost billable hours" / "increased cost of working" to offset my battery purchase against.

At the absolutely opposite extreme I'm not sure "not having to reset all the electric clocks in the house", after a powercut, would be sufficient justification!! but there may well be some folk that are somewhere in the middle?

Car EV battery connected to house might become a thing but, personally, I don't want to get home and then discharge my car into the house ... I might need to drive somewhere urgently ... I'd prefer to come home and plug in, although currently I schedule charging for E7, so in practice I don't charge from arrival at home until midnight (but I do charge immediately if I arrive home below 20% because its better that the battery is not left in that state, and "I might need to drive somewhere urgently")

A distributed battery system, at a local-ish level, would achieve better economies of scale than individual-dwelling-batteries, but would it achieve the same up-time for each house? Residential installation also enables, maybe?, the power companies to offload the capital cost of batteries to consumers ... can't see us getting lower cost-per-unit in return though, eh?!! Although when TOU arrives maybe I will be able to sell my stored juice at peak for a worthwhile price

That said I am interested to hear about the performance of the alternatives to FLA batteries - the emphasis here being on real world data and not lab testing or agenda based evidence trawled off the web

Dunno if it is useful data, but there is data for Tesla batteries used in their cars (which have a decent battery-management-system). Taxis with very high mileage, somewhat abusive charging - high kW charging, often charging to 100% and leaving the battery in that state (normal daily recommendation is to charge to 90% and if charging to 100% "set off promptly"). At around 200,000 miles (battery range approx 200 miles, but I don't know how often discharged to low state-of-charge, so maybe approaching 1,000 cycles - typically they are approaching 100,000 miles p.a. e.g. airport-run taxi companies) battery degradation is around 6%, and it seems that most of that happens early on, and levels off thereafter.

fully understand their generation patterns and consumption needs, reduce consumption to what is actually necessary and then determine the best installation. Seems this fundamental first step is in danger of being skipped in favour of  "I must have a domestic battery - now how can I go about justifying it"

Telsa (and I'm sure others) have some fancy graphs on their APP showing where the battery / PV has been used/charged relative to grid import/export.  That's after-the-installation of course, and doesn't tell you that your Fridge has a filthy condenser grill and just cleaning that would dramatically reduce consumption (Yeah, BTDTGTTS ...). They also have an open API, so opportunity for doing "stuff" with the data.

Jaguar have provided an APP that records your (normal, current) journeys and then makes recommendations on how your life would be / cash-savings etc. if you bought their i-Pace EV.  Maybe similar APPs exist for Smartmeter folk to show cost effectiveness of PV, Battery-installation, etc.  Its a lot different for someone using energy during the day, when PV would help, to someone who is out to work all day.
« Last Edit: September 20, 2018, 02:33:04 PM by kristen » Logged
« Reply #29 on: September 20, 2018, 07:43:23 PM »

Heather H; I heart your point of view.

Kristen can you share with the class this Neo-Tesla "data" please?
Would you mind awfully citing the source and verifying the fidelity?

In the summary can you explain to me the following:

How does it compare to the device's projected longevity and functionality info? If you can find any.
What is the cycle depth in these figures? Can you express it in terms of total energy extracted instead of cycles?  Does this meet specification? What is the specification?
Are users pushing this technology to 100% claimed duty cycle or if not what is the nominal duty cycle generally seen by users?
What is the Neo-Tesla battery round trip efficiency independently tested figures? What is the 100% charged per cell cut-off voltage...and the 0% Charged Cut-off voltage? What are the parameters by which they measure battery degradation?

Did you know that Neo-Tesla rate their batteries down to 70% of original capacity while all the rest of the scientific community have agreed on an 80% threshold? Did you realise this disqualifies them from comparative testing with their peers?

What is the true lifetime cost of a kWh from a Neo-Tesla PoowerWall?
What is the PoowerWall self-consumption in ambient -5įC at night?
Does it work in a powercut?
Can you charge it from utility mains or a genset?
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