Is solar battery storage worth it?

Reed_Richards

I bought my battery five and a half years ago; since then prices have fallen a lot so what I paid for mine makes no contribution to the debate about whether batteries are worth it now.  It's a 6.5 kWh battery, you probably have a better idea about what that would cost today than I do, @Screwdriva.

I bought my car, a Mokka-e from a dealer, almost exactly a year ago.  it cost me £22k was 3 months old and had done 1,700 miles.  A quick look on Autotrader shows I might pay down to about £20,5k for an ICE Mokka of a similar age and mileage and about £20k for the equivalent Mokka-e today.  So given the very small difference in price between EV an ICE I don't think the actual price is relevant.      

Martyn1981

Screwdriva said:

Reed_Richards said:

With the current £7.5k grant towards a heat pump and the very competitive retrofit installation deals being offered by Octopus you could perfectly possibly install the heat pump for less than the cost of your gas boiler. 

Absolutely - my own home was quoted £500 less for a heat pump at £2500, which is phenomenal value for the installation itself. But I would need to pay for a new hot water cylinder as my megaflo is incompatible. That said, my "drum beating" was about actual running costs.

Still waiting for you to share a cost for batteries and an EV before we have a credible debate on the true running costs for both systems. Should be fairly easy to model out once you share these. 

I don't think it's fair to ask the cost of an EV, it's the cost difference that is important. And as Reed Richards has explained, some can be bought at reasonable prices these days, and secondhand models are often good value. Next, after taking into account the lower running costs, a BEV might (I totally appreciate 'might' as we all have differing demands) have a lower TCO (total cost of ownership).

[Purely as an example, it might be worth someone spending £10k on a 3yr old 180 mile range BEV, if they can then drive around at sub 2p/mile. Or it might not be viable at all, but worth offering up the info and suggestions, since energy, heating and transport are all in a transitionary state at the moment.]

Going back to your original point, you were looking at the price of gas, but after taking the boiler efficiency ~90% into account, cheap rate leccy is only slightly more expensive, and if you use a HP, then a COP of 2 to 4 is possible, making the HP much cheaper on a kWh(t) basis.

Going bacl to the thread title, and possibly my mentioning of A2A units recently, that may have sparked this recent discussion - then adding in a battery, at an appreciable cost, of course, means that cheap rate leccy + HP COP may be possible for some/all of the day. This easily beats the cost of heat energy that you suggested "remains hard to beat financially".

That would seem to tick the MSE element of energy in general, and the G&E intention of this board too.

pensionpawn

Martyn1981 said:

Screwdriva said:

Reed_Richards said:

With the current £7.5k grant towards a heat pump and the very competitive retrofit installation deals being offered by Octopus you could perfectly possibly install the heat pump for less than the cost of your gas boiler. 

Absolutely - my own home was quoted £500 less for a heat pump at £2500, which is phenomenal value for the installation itself. But I would need to pay for a new hot water cylinder as my megaflo is incompatible. That said, my "drum beating" was about actual running costs.

Still waiting for you to share a cost for batteries and an EV before we have a credible debate on the true running costs for both systems. Should be fairly easy to model out once you share these. 

I don't think it's fair to ask the cost of an EV, it's the cost difference that is important. And as Reed Richards has explained, some can be bought at reasonable prices these days, and secondhand models are often good value. Next, after taking into account the lower running costs, a BEV might (I totally appreciate 'might' as we all have differing demands) have a lower TCO (total cost of ownership).

[Purely as an example, it might be worth someone spending £10k on a 3yr old 180 mile range BEV, if they can then drive around at sub 2p/mile. Or it might not be viable at all, but worth offering up the info and suggestions, since energy, heating and transport are all in a transitionary state at the moment.]

Going back to your original point, you were looking at the price of gas, but after taking the boiler efficiency ~90% into account, cheap rate leccy is only slightly more expensive, and if you use a HP, then a COP of 2 to 4 is possible, making the HP much cheaper on a kWh(t) basis.

Going bacl to the thread title, and possibly my mentioning of A2A units recently, that may have sparked this recent discussion - then adding in a battery, at an appreciable cost, of course, means that cheap rate leccy + HP COP may be possible for some/all of the day. This easily beats the cost of heat energy that you suggested "remains hard to beat financially".

That would seem to tick the MSE element of energy in general, and the G&E intention of this board too.

I agree, it's the cost difference between the EV version of the equivalent spec ICE model which is my metric. You just can't compare with a cheaper model / make EV and say there you go, cheap driving! There's also maximum summer range and realistic winter range, insurance (through the roof recently on some EVs) and the cost of a charging point, which just alone can take a year to recover, dependent on annual mileage (we're around 6000pa, much less when I fully retire). Of course, as others have stated, it's horses for courses. When I was 20 years younger I was commuting 140 miles a day and the equation would be much different. I'm all for getting an EV / battery, however they have to be at least fiscally neutral compared to my current situation, to make the jump.

On the subject of using A/C in heating mode, the jury is still out for us. The units are obviously high up on the wall and of course hot air rises. Now over time the room should fully heat up however at the moment we are conscious that the floor area remains cool (below the knees when seated). This is a quite different method of heating compared to radiated heat at seating level. I'm going to keep going with my trial, tweaking this and that, however I only have until Mrs PP says "enough is enough, I'm freezing, turn the CH back on" lol!

pensionpawn

Martyn1981 said:

Screwdriva said:

Reed_Richards said:

With the current £7.5k grant towards a heat pump and the very competitive retrofit installation deals being offered by Octopus you could perfectly possibly install the heat pump for less than the cost of your gas boiler. 

Absolutely - my own home was quoted £500 less for a heat pump at £2500, which is phenomenal value for the installation itself. But I would need to pay for a new hot water cylinder as my megaflo is incompatible. That said, my "drum beating" was about actual running costs.

Still waiting for you to share a cost for batteries and an EV before we have a credible debate on the true running costs for both systems. Should be fairly easy to model out once you share these. 

I don't think it's fair to ask the cost of an EV, it's the cost difference that is important. And as Reed Richards has explained, some can be bought at reasonable prices these days, and secondhand models are often good value. Next, after taking into account the lower running costs, a BEV might (I totally appreciate 'might' as we all have differing demands) have a lower TCO (total cost of ownership).

[Purely as an example, it might be worth someone spending £10k on a 3yr old 180 mile range BEV, if they can then drive around at sub 2p/mile. Or it might not be viable at all, but worth offering up the info and suggestions, since energy, heating and transport are all in a transitionary state at the moment.]

Going back to your original point, you were looking at the price of gas, but after taking the boiler efficiency ~90% into account, cheap rate leccy is only slightly more expensive, and if you use a HP, then a COP of 2 to 4 is possible, making the HP much cheaper on a kWh(t) basis.

Going bacl to the thread title, and possibly my mentioning of A2A units recently, that may have sparked this recent discussion - then adding in a battery, at an appreciable cost, of course, means that cheap rate leccy + HP COP may be possible for some/all of the day. This easily beats the cost of heat energy that you suggested "remains hard to beat financially".

That would seem to tick the MSE element of energy in general, and the G&E intention of this board too.

94% for my Viessmann.

Martyn1981

pensionpawn said:

Martyn1981 said:

Screwdriva said:

Reed_Richards said:

With the current £7.5k grant towards a heat pump and the very competitive retrofit installation deals being offered by Octopus you could perfectly possibly install the heat pump for less than the cost of your gas boiler. 

Absolutely - my own home was quoted £500 less for a heat pump at £2500, which is phenomenal value for the installation itself. But I would need to pay for a new hot water cylinder as my megaflo is incompatible. That said, my "drum beating" was about actual running costs.

Still waiting for you to share a cost for batteries and an EV before we have a credible debate on the true running costs for both systems. Should be fairly easy to model out once you share these. 

I don't think it's fair to ask the cost of an EV, it's the cost difference that is important. And as Reed Richards has explained, some can be bought at reasonable prices these days, and secondhand models are often good value. Next, after taking into account the lower running costs, a BEV might (I totally appreciate 'might' as we all have differing demands) have a lower TCO (total cost of ownership).

[Purely as an example, it might be worth someone spending £10k on a 3yr old 180 mile range BEV, if they can then drive around at sub 2p/mile. Or it might not be viable at all, but worth offering up the info and suggestions, since energy, heating and transport are all in a transitionary state at the moment.]

Going back to your original point, you were looking at the price of gas, but after taking the boiler efficiency ~90% into account, cheap rate leccy is only slightly more expensive, and if you use a HP, then a COP of 2 to 4 is possible, making the HP much cheaper on a kWh(t) basis.

Going bacl to the thread title, and possibly my mentioning of A2A units recently, that may have sparked this recent discussion - then adding in a battery, at an appreciable cost, of course, means that cheap rate leccy + HP COP may be possible for some/all of the day. This easily beats the cost of heat energy that you suggested "remains hard to beat financially".

That would seem to tick the MSE element of energy in general, and the G&E intention of this board too.

I agree, it's the cost difference between the EV version of the equivalent spec ICE model which is my metric. You just can't compare with a cheaper model / make EV and say there you go, cheap driving! There's also maximum summer range and realistic winter range, insurance (through the roof recently on some EVs) and the cost of a charging point, which just alone can take a year to recover, dependent on annual mileage (we're around 6000pa, much less when I fully retire). Of course, as others have stated, it's horses for courses. When I was 20 years younger I was commuting 140 miles a day and the equation would be much different. I'm all for getting an EV / battery, however they have to be at least fiscally neutral compared to my current situation, to make the jump.

On the subject of using A/C in heating mode, the jury is still out for us. The units are obviously high up on the wall and of course hot air rises. Now over time the room should fully heat up however at the moment we are conscious that the floor area remains cool (below the knees when seated). This is a quite different method of heating compared to radiated heat at seating level. I'm going to keep going with my trial, tweaking this and that, however I only have until Mrs PP says "enough is enough, I'm freezing, turn the CH back on" lol!

Yep, lots of fun experimenting.

In my opinion, the A2A will warm a room, much faster than the GCH, but of course the GCH is trying to warm most of the house at the same time. That's actually another significant benefit of the A2A as you may not want to heat the whole house, especially during the spring and autumn.

Not at all scientific, but we use the room door as a temp control if we want to vary heat demand for the room, v's warm through the house. At night, I put the A2A temp higher, ~24C, and leave the door wide open to spread through the house.

Not wishing to digress to far, but if you, or anyone else with relatively low mileage is considering getting a BEV, with home charging, then there may be no need for a 'home charger'. Simply using the 'granny' charger will suffice at levels of ~6,000 miles pa, if spread evenly, since that's ~16 miles per day, and just 6hrs of cheap rate at ~2kW, will give you 40 to 50 miles of range.

We do about 14k miles pa, across 2 BEV's, and hardly use the main charger Mch - Sept, as I try to maximise PV charging, so at a lower level, but of course that means longer charging through the day which requires PV, and a batt helps, since it covers peaks and troughs in cloudy weather (does the same for A2A use too).

In the winter, we tend to charge mostly off cheap rate, so then use the 7kW charger, just less often than you would with a granny charger.

I'd actually suggest (again, just my opinion) not bothering to get a smart charger at ~6k miles pa.

Martyn1981

pensionpawn said:

Martyn1981 said:

Screwdriva said:

Reed_Richards said:

With the current £7.5k grant towards a heat pump and the very competitive retrofit installation deals being offered by Octopus you could perfectly possibly install the heat pump for less than the cost of your gas boiler. 

Absolutely - my own home was quoted £500 less for a heat pump at £2500, which is phenomenal value for the installation itself. But I would need to pay for a new hot water cylinder as my megaflo is incompatible. That said, my "drum beating" was about actual running costs.

Still waiting for you to share a cost for batteries and an EV before we have a credible debate on the true running costs for both systems. Should be fairly easy to model out once you share these. 

I don't think it's fair to ask the cost of an EV, it's the cost difference that is important. And as Reed Richards has explained, some can be bought at reasonable prices these days, and secondhand models are often good value. Next, after taking into account the lower running costs, a BEV might (I totally appreciate 'might' as we all have differing demands) have a lower TCO (total cost of ownership).

[Purely as an example, it might be worth someone spending £10k on a 3yr old 180 mile range BEV, if they can then drive around at sub 2p/mile. Or it might not be viable at all, but worth offering up the info and suggestions, since energy, heating and transport are all in a transitionary state at the moment.]

Going back to your original point, you were looking at the price of gas, but after taking the boiler efficiency ~90% into account, cheap rate leccy is only slightly more expensive, and if you use a HP, then a COP of 2 to 4 is possible, making the HP much cheaper on a kWh(t) basis.

Going bacl to the thread title, and possibly my mentioning of A2A units recently, that may have sparked this recent discussion - then adding in a battery, at an appreciable cost, of course, means that cheap rate leccy + HP COP may be possible for some/all of the day. This easily beats the cost of heat energy that you suggested "remains hard to beat financially".

That would seem to tick the MSE element of energy in general, and the G&E intention of this board too.

94% for my Viessmann.

If we're using peaks, then I'll raise you a COP of 5!  

Screwdriva

Martyn1981 said:

I don't think it's fair to ask the cost of an EV, it's the cost difference that is important. And as Reed Richards has explained, some can be bought at reasonable prices these days, and secondhand models are often good value. Next, after taking into account the lower running costs, a BEV might (I totally appreciate 'might' as we all have differing demands) have a lower TCO (total cost of ownership).

[Purely as an example, it might be worth someone spending £10k on a 3yr old 180 mile range BEV, if they can then drive around at sub 2p/mile. Or it might not be viable at all, but worth offering up the info and suggestions, since energy, heating and transport are all in a transitionary state at the moment.]

Going back to your original point, you were looking at the price of gas, but after taking the boiler efficiency ~90% into account, cheap rate leccy is only slightly more expensive, and if you use a HP, then a COP of 2 to 4 is possible, making the HP much cheaper on a kWh(t) basis.

A few corrections/ suggestions if I may.

1) Viessmann 200-W gas boilers regularly achieve 95% efficiency (officially rated 98% ERP) when at maximum modulation. This isn't peak performance by any means. 

2) I'm not sure what your requirements for an EV but I suspect limited range, costs of ownership of a cheap, used EV and lack of warranty coverage would make some (including me) very anxious. 

3) Disregarding #2 entirely, I can't see a way to purchase a usable EV + home battery for under £20K.

My annual electricity consumption is 1600 kWh. Gas consumption is ~13K kWh. Here are the key metrics I use to model this:

Heat pump SCOP: 3  (As shared by Reed)
Boiler efficiency: 95%
Cost of Octopus Heatpump installation: £2500
Cost of ASHP DHW Cylinder: £2000
Cost of V200 boiler installed: £3000
Assumed Cost of EV: £15K
Assumed Cost of Charger: £1K
Assumed Cost of 13.5kWh Battery: £6K 
Average rate for Gas Tracker : 5p per kWh
Average rate for Intelligent Octopus Go : 8.5p per kWh

I have disregarded the cost to upgrade heat emitters as I personally wouldn't need this, but others may. I've also assumed the EV/ Charger is compatible with IOG (not all are). Do let me know if I've missed something - would love to see how the numbers work against what I have shared above. 

Martyn1981

Happy for you to use a SCOP of 3, I actually suggested 2 when talking about running through the night, since that's a fair average, but obviously, you can't use 94%/95% for a boiler average, that would be extreme cheating. 90% is, I believe entirely fair and reasonable, is it not?

No need to get an old out of warranty EV, as I mentioned, a 3yr old would be great, lots of choice at ~£10k, for those that drive closer to the UK average of 7,000 miles pa..

Obviously depends on your requirments, but a battery and BEV of £5k each is possible, which appears to be well under your figure of £20k.

Wow 13k kWh of FF gas, we're down to around 6,000kWh, and that's with only limited use of an A2A. Hoping to almost half that via the cheap rate, 2x A2A and battery.

I suspect the reason your figures are somewhat questionable, is that you are taking worst case for one, and best case for the other, rather than my approach of trying to be fair and reasonable throughout.

Screwdriva

Martyn1981 said:

Happy for you to use a SCOP of 3, I actually suggested 2 when talking about running through the night, since that's a fair average, but obviously, you can't use 94%/95% for a boiler average, that would be extreme cheating. 90% is, I believe entirely fair and reasonable, is it not?

No need to get an old out of warranty EV, as I mentioned, a 3yr old would be great, lots of choice at ~£10k, for those that drive closer to the UK average of 7,000 miles pa..

Obviously depends on your requirments, but a battery and BEV of £5k each is possible, which appears to be well under your figure of £20k.

Wow 13k kWh of FF gas, we're down to around 6,000kWh, and that's with only limited use of an A2A. Hoping to almost half that via the cheap rate, 2x A2A and battery.

I suspect the reason your figures are somewhat questionable, is that you are taking worst case for one, and best case for the other, rather than my approach of trying to be fair and reasonable throughout.

I have used my own household's data shared above, as I can't speak to other use cases,. Our V200 routinely achieves the efficiency I've shared (this isn't just me stating this- there's a bucketload of Viessmann installers who attest to this as well).

There is no way a £5K BEV is pragmatic regardless of how possible it may be. For us, a minimum 200 usable mile driving range is a must have. Others may be different. 

Just emphasizing this to counter the accusations above. Again, please feel free to use the above numbers to highlight a superior running cost vs. capital cost ratio over the next decade for us. Granted the ASHP warranty probably won't be that long but 10 years is a nice round number). 

Reed_Richards

Screwdriva said:

 For us, a minimum 200 usable mile driving range is a must have. 

Because?  Do you frequently make journeys of over 200 miles without stopping anywhere long enough to recharge an EV.  That must mean you drive far further each year than the average 7000 miles. 

My Mokka-e has a nominal range of 216 miles and can come close to 200 miles in summer; longer range EVs are available.  I have driven about 9000 miles in it in the last year and I had to charge it away from home three times.  If I was driving 250 miles on a trip I would only need to add 15 kW to give me a safe margin to get home and with one of the more rapid chargers that would take about half an hour.