2 Battery or Not 2 Battery

ASavvyBuyer

pensionpawn wrote: »

3. So what is going to give you the best return on all that excess solar energy. For me it's moving to an EV. I export around 2.9Mwhrs a year and dumping some (most?) of that in a car to replace fossil fuel is a no brainer in running cost (no car tax either, yet!) Even charging it with day rate is around 5 times cheaper. However the extra capital premium cost for an EV needs to be carefully weighed up. Also, government grant may expire (reduce probably) in October as will subsidy on home charging point. Battery will have it's day, though not for a few year I reckon.

That's why we decided to go for an EV now, rather than a battery. IMHO having an EV does more to replace fossil fuel usage than installing a battery. Also, it helps by switching to a 100% green tariff with a supplier that only purchases and invests in renewable energy.
Also, when V2H becomes available, at a reasonable cost, the car already has a suitable interface.

pensionpawn

I'm all for going green however the budget has to balance first. Of course, playing Devil's Advocate, and I'm sure that there are plenty of threads on this, the impact to the environment of digging up materials for, transporting said materials to factories, manufacturing and disposing of batteries isn't insignificant.
I have this crazy idea in my head of a system built into a house, like a chimney stack, that lifts a weight up when the sun is shining and lets it fall when electricity is needed. A capacitor would be the buffer between demand and supply. Much like the water store emergency systems for the grid in Wales and Scotland. One for retirement, lol!

EricMears

pensionpawn wrote: »

I have this crazy idea in my head of a system built into a house, like a chimney stack, that lifts a weight up when the sun is shining and lets it fall when electricity is needed.

Afraid I can't remember the exact formula but ISTR that to be any use you'd need a weight somewhat in excess of a thousand tons and a lift of several hundred feet (which wouldn't fit neatly into most chimneys).

Heedtheadvice

admission. Have not read all this thread....
....but my first though was...


if you buy expensive cars (electrics and hybrids are expensive currently in terms of capital outlay) and do not get much benefit from them economically (they are only economic solutions if used regularly as the capital depreciation etc. far out way any saved running costs vs fossil fueled cars) then economics probably should not come into your decisions regarding solar and storage.
Go for what is best in terms of environment and that could be to install on grid PV of whatever maximum size you can get agreement for, virtually ignore FIT, install as much storage as is going to be practical, and then do the same for an off grid system?


Compared to what £80K+? for cars two of which sit idle for much of the time what is another £20K or so?


Not trying to be cheeky or anything but buying high capital cost items that do not save much money (it is the running costs that potentially save a lot and it seems that not a lot of running will happen?) or take so long to payback upon investment........


I am all for Solar generation, battery storage, electric cars etc. but usually the economics play a big part in the purchasing decisions. Most of us can not sensibly do what we would like to do owing to financial/economic decisions but if you can afford to do so and wish to be as green as possible...just go for it!


I am just jealous!!

pensionpawn

Also, in addition to my first post, as a step 1B check how much you export over the year. This also needs to be taken into consideration. For example, I import 5.2 MWhrs and export around 2.9MWhrs, so I would still have to pay for 2.3MWhrs of electricity even if I could capture (which one Powerwall* couldn't) all my export. However, if you have Economy 7 (which I do) a battery could offset a considerable amount of electrical import cost over the winter months by sucking up 13.5kWhrs a night at 6.75p/kWhr. Also consider this, chucking your 'spare' cash into your pension and getting 20% off the government for the privileged, is undoubtedly the best use of your 'spare' money (after all, this is a money saving forum)!

* - I did model the impact of having two Powerwalls (as installation cost shouldn't double and there may be some multi purchase discount...) and this increased my saving on import marginally to 40% (not worth it).

Finally, if you do have E7, bear in mind that the idea of buying a Powerwall 2 to capture all that free sunshine to dump into your car overnight is really only saving you against the E7 rate of ~ 6.75p/kWhr. I just can't see how that makes any economic sense. I get the argument that some things we just buy because we want them and if you are an eco warrior first and foremost, why not. It certainly drives me mad to see blue skies and tons of export, put the dishwasher on (which I call my cloud summoning device), and watch the generation plummet with a corresponding spike in import. I have to remind myself that buying my own electricity back later is still the most cost effective solution. When it comes to splashing the cash, to save on costs over a term, it just has to balance for me financially first.

pensionpawn

My last two cars cost around £23k and £26k new. The EV (similar spec) that I'm considering is expected to cost £30k upwards (after Gov grant I believe). So, an average of £5k more to offset against fossil fuel cost and car tax. Petrol and car tax cost me around £1200 a year so RoI after 4-5 years, probably more like 5. So you have to be someone who doesn't mind keeping a car beyond 5 years to start to see the benefit.... I love tech and the idea of Powerwalls / EVs however it's not a no brainer at present. However if the Gov grant was to disappear then now may be the sweet spot to change...?

Heedtheadvice

I like your thinking Pensionpawn but would add that you need to also take into account depreciation and risk. Currently (no pun!) that for electric cars is greater than for conventional ones on average so you would need to keep it for more than the five years before you are quids in.


That then starts approaching battery life warranties and reduced battery performance and the increasing risk that, should the battery fail, a whopping bill in the order of £15K to replace. That would be more than the value of the vehicle so might not be a good move (wondering about the warranty on a replacement batt and the parallel risk to motors etc. that have a much reduced warranty!)


Of course there are risk with conventional vehicles too and new unknown charges that will no doubt come to be applied to meet our environmental goals (and many other cost such as servicing) but generally not so great as the prospective one of the battery failure or significantly reduced performance. It really is early days to get accurate assessments for the lifetime costs of domestic EVs IMHO


Edit: Some data to explain my depreciation concerns.


Consider two similar most popular mid range cars: a Ford Focus 1.6 petrol and a Nissan Leaf Electric (subsidised). Depreciation over three years is similar (52% and 55% respectively) but monetary cost for depreciation of the former is £8.5K and the latter £13K.
Info from https://www.insurethegap.com/articles/depreciation-of-electric-cars-varies-greatly-across-different-models

pensionpawn

Now I initially thought that depreciation would be as per conventional cars however that is not necessarily the case. Watching this video from the Fully Charged Live event at Silverstone this summer indicates that for certain electric cars, they appreciate in value (discussed at 5 mins 40s) / don't lose value! Also for the car I am interested in the manufacturer is offering a warranty on the battery for the same period as a Powerwall 2, 10 years. So that does give me the confidence to switch to an EV.

System

pensionpawn wrote: »

Now I initially thought that depreciation would be as per conventional cars however that is not necessarily the case. Watching this video from the Fully Charged Live event at Silverstone this summer indicates that for certain electric cars, they appreciate in value (discussed at 5 mins 40s) / don't lose value! Also for the car I am interested in the manufacturer is offering a warranty on the battery for the same period as a Powerwall 2, 10 years. So that does give me the confidence to switch to an EV.

Having been an EV owner for 4 years, I have yet to see an EV appreciate in value. EVs are a bit like iPhones and iPads. People want the latest technology and they are prepared to pay for it. For example, would you buy an EV today with a 94aH battery today, when the same model will be announced next week in Paris with a 120 aH battery for roughly the same price?

There is also a lot more to an EV than just the battery. I think that I am correct in saying that 8 year warranties on batteries are standard in the UK. That doesn't mean that in 8 years time the battery will have the same ability to charge (range) as was the case when you bought it!

The other thing to bear in mind is that the drivetrain (which includes all the high voltage cables and the clever electronics needed for charging and battery cooling) is only covered by the standard warranty. Repairs can therefore be very expensive which is reflected in the cost of extended insurance-based warranties - now over £1000/year for an i3. Would I run my i3 without an extended warranty: the answer is a definite 'No'.

In sum, EVs are fun to drive and cost of running them is low PROVIDED you do not have to pay for expensive repairs which can run into £000s. However, the purchase cost is higher than a standard ICE so this has to be factored into your thinking. EVs make most sense for those who have a long standard commute which is within the range and back of a home charge. Relying on public charging is a 'fools errand'.

pensionpawn

I think Hengus touches on a number of salient points. When buying a car, whether it be fossil fuel, EV or somewhere in between, it is a personal decision for us. However unless buying a classic car partially as an investment, we all expect our car to fall in value, the biggest drop attributable to solely to losing it's status as new. However this fall in value is usually compensated for considerably by the incentives offered by a manufacturer to buy another new car. I think what some (most?) EV commentators are saying is that this fall is less for certain EV than you may expect as the cheaper running costs compare well against second hand fossil fuel cars. Personally, I buy the car I need / want and if its doesn't lose too much value by the time I wish to swap, great.

Of course the range will fall and that needs to be factored in, however that may not be a significant issue for the local commuter and by that time the near zero running costs may have created significant inertia to swapping for a new car with all it's associated costs. I know at least one manufacturer that is warranting their batteries for 10 years (must be good for sales) which I find very tempting.

Standard warranty exclusions on the other electrical components of the drive train is something I had not really considered and needs further investigation as I agree with you entirely.

EVs are not a no brainer for me yet however I am conscious that governments subsidies that make them worth considering are potentially at risk which will change the economics drastically for me. Hence, as others in the EV industry have commented, we may be at a sweet spot to swap and if you are happy to stick with your new EV car for a minimum of 5 years, then now looks a good time to go EV.