Is solar battery storage worth it?

Screwdriva

pensionpawn said:

Thanks for the suggestions. Flux offers a cheap rate between 2am - 5am however as I don't get up for work until 6:30am I don't think it will be cost effective / I'll see much benefit? I have UFH over 3/4 of the ground floor area and over the winter I have switched that on from 4:30 - 5:00 with the only noticeable effect being fiscal! Even though insulated with 10mm backboard it still loses energy quickly unless continually topped up, which then makes it very effective. I know I could leave the A/C on from 4:30, however with no one awake for at least 2 hours it's debatable how that would be more cost effective than my 2 year old Viessmann / Nest running and modulating down to 10% at 6p. I'll keep it in mind.

That Viessmann (paired with the Gas tracker tariff <5p) remains hard to beat financially, even with panels.

greenbee

I honestly think it depends on your personal circumstances and priorities. My primary reason for having the battery is for the EPS in case of power cuts as I work from home and have no local office I can go to if there is an issue. However, it also allows me to use stored solar for some heating (towel rails) and hot water when there is no solar which reduces my oil consumption and therefore the frequency of top-ups (oil tank is too small for the house) - and gives me a backup if I do run low/out at inconvenient times. While I will probably invest in more panels, I don't think I'll expand battery storage in the near future as the 10kw I have appears to be sufficient to minimise grid use between sunset and sunrise. 

Reed_Richards

Screwdriva said:

That Viessmann (paired with the Gas tracker tariff <5p) remains hard to beat financially, even with panels.

Try this: charge battery overnight on Eon NextDrive EV tariff @ 6.9p per kWh, use that to run heat pump, let's assume COP=3 (although probably better at this time of year), top-up battery with solar when the sun gets up, costs 2.3p per kWh.   

pensionpawn

greenbee said:

I honestly think it depends on your personal circumstances and priorities. My primary reason for having the battery is for the EPS in case of power cuts as I work from home and have no local office I can go to if there is an issue. However, it also allows me to use stored solar for some heating (towel rails) and hot water when there is no solar which reduces my oil consumption and therefore the frequency of top-ups (oil tank is too small for the house) - and gives me a backup if I do run low/out at inconvenient times. While I will probably invest in more panels, I don't think I'll expand battery storage in the near future as the 10kw I have appears to be sufficient to minimise grid use between sunset and sunrise. 

I agree that a must have feature of a battery is continuity of service in the event of a power cut, which with only 2 in 28 years where I live, is unlikely. What we came close to and what you can't rule out in future, with government energy policy / world events, is power rationing. What I can't consider coping with is a future winter sunny day and no energy because solar panels by will be switched off due power rationing. So, I see part of the cost of a battery install as an insurance policy service continuity write off and not part of the RoI calculation. That said, I still can't see a cost effective battery solution at present for me. I'd be better off putting £10k into my pension, getting the tax rebate, withdrawing it (I'm over 55) over time / throwing the £12k5 into a good interest bearing vehicle to pay my energy bills over the next 10-15 years!

Screwdriva

Reed_Richards said:

Screwdriva said:

That Viessmann (paired with the Gas tracker tariff <5p) remains hard to beat financially, even with panels.

Try this: charge battery overnight on Eon NextDrive EV tariff @ 6.9p per kWh, use that to run heat pump, let's assume COP=3 (although probably better at this time of year), top-up battery with solar when the sun gets up, costs 2.3p per kWh.   

Don't you need to purchase batteries and an EV for that tariff? How many thousands (£) should I add for upfront capital expenditure? 

Reed_Richards

@Screwdriva, you were claiming that a particular running cost was hard to beat and I beat it very easily.  If you want to factor in other costs then you should factor in the cost of a Viessmann boiler, the cost of an ICE car and the cost of running it  Then we can make a comparison.  My EV, a Mokka-e, appeared to be comparable in price to the ICE equivalent and it's certainly cheaper to run than an ICE would be, so that's a double win for me.  

Screwdriva

Reed_Richards said:

@Screwdriva, you were claiming that a particular running cost was hard to beat and I beat it very easily.  If you want to factor in other costs then you should factor in the cost of a Viessmann boiler, the cost of an ICE car and the cost of running it  Then we can make a comparison.  My EV, a Mokka-e, appeared to be comparable in price to the ICE equivalent and it's certainly cheaper to run than an ICE would be, so that's a double win for me.  

I don't see how an ICE car has anything to do with the above comparison as it does not allow access to any favorable tariffs like the one you have shared above. Same goes for batteries. As such, I don't see you beating anything (other than your own drum).

Again, how much should I list as a cost for an EV and a home battery system to compare tariffs and runnings costs? £15K? £20K? A Viessmann 200-W gas boiler costs ~£3K installed for comparison. 

pensionpawn

Reed_Richards said:

@Screwdriva, you were claiming that a particular running cost was hard to beat and I beat it very easily.  If you want to factor in other costs then you should factor in the cost of a Viessmann boiler, the cost of an ICE car and the cost of running it  Then we can make a comparison.  My EV, a Mokka-e, appeared to be comparable in price to the ICE equivalent and it's certainly cheaper to run than an ICE would be, so that's a double win for me.  

In my case I chose a Viessmann boiler as 1. I needed a new boiler as my 26 year old Ideal Classic was about to fail and 2. they work well with salt water softener systems. They are also very efficient and Smart. I do not own an EV as I do not do the necessary mileage required to pay off the extra capital cost compared to an ICE vehicle. My only cost is what I paid for my panels / inverter / solar divert, which took 7.5 years to recover, and now my annual energy bill is £54 last year and projected ~ £154 this year. I am happy with this.

Reed_Richards

Screwdriva said:

Reed_Richards said:

@Screwdriva, you were claiming that a particular running cost was hard to beat and I beat it very easily.  If you want to factor in other costs then you should factor in the cost of a Viessmann boiler, the cost of an ICE car and the cost of running it  Then we can make a comparison.  My EV, a Mokka-e, appeared to be comparable in price to the ICE equivalent and it's certainly cheaper to run than an ICE would be, so that's a double win for me.  

I don't see how an ICE car has anything to do with the above comparison as it does not allow access to any favorable tariffs like the one you have shared above. Same goes for batteries. As such, I don't see you beating anything (other than your own drum).

Again, how much should I list as a cost for an EV and a home battery system to compare tariffs and runnings costs? £15K? £20K? A Viessmann 200-W gas boiler costs ~£3K installed for comparison. 

As you, @Screwdriva, were beating the drum for your own choice of Viessman and gas. 

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. 

The point about the car is that if you own a car you can choose between one with an ICE or one without, an EV.  The cost of some EVs (like the one I drive) has fallen to a similar cost to the ICE equivalent, @pensionpawn, the EV allows you to get a cheap night time electricity tariff, that allows you to run the EV much more cheaply than an ICE.  And you can also use that cheap electricity to charge a battery, in my case one that came when I installed solar PV panels five and a half years ago.

Since I got my EV and moved to an EV tariff my use of the battery has changed radically.  Now I charge it up cheaply at night to a state of charge that I estimate will see me through until the sun comes out enough to recharge it.  This has made solar battery storage a lot more worth it for me than it used to be. 

The answer to the question posed in this topic is very far from straightforward and highly dependent on individual circumstances.   

Screwdriva

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.