Should we buy a 2nd solar battery

SuzeQStan

I know solar batteries can be a contentious issue on MSE forums - however OH & I invested in solar panels 5.5 kWh + battery 6.5 kWh approx 20 months ago and we are wondering if adding a 2nd battery to our existing system would be beneficial.

am sure that most with solar panels on these forums will have had a similarly rubbish last couple of weeks - a couple days ago we generated 0.1kwh for the entire day 😱

At the moment we are on TOU 🐙 Intelligent Go tariff as we have a EV. 

So between 11:30-5:30am for 7p per kWh we are charging the solar battery to power our home during the following day/evening, charging the EV with dedicated charger up to 2x week, and running the dishwasher, washing machine & tumble dryer and often oven for next days evening meal as these are all on a programmable timer.

Because of rubbish winter solar
generation - even with fully charging our battery at night - we are running out of battery by about 9pm the next day so then find ourselves on SVT last 2.5 hours of the day. And although this is only costing us average 50p till the IO tariff kicks in 11:30pm it is playing on my mind. 

 And it is curtailing our activities as we are aware the battery is empty and any energy we use will be 3x more costly on the SVT. We are high usage household averaging 5k kWh per annum (bearing in mind this includes EV charging)

We have been looking at adding a 2nd battery as the price of this has more than halved since we purchased it at time of solar install. In January 2023 we paid outright/no finance £3k for our existing Growatt 6.5 kWh battery (& a further £7k for the solar panel/inverter install at the same time)

have found below cost on shallow search:

£1350.00 growatt 6.5kwh battery (inclusive of VAT as these are only vat free if they are  purchased with install)
£45.00 parallel cable
£70.00 shipping
total £1465.00

My OH is handy and says would be straightforward for self install. 

I know that folk will quote my own cost back at me - 50p per day means payback of 8.5 years & estimate battery lifetime is 10 years.

there is a certain element of not having to worry about the battery running out which is attractive to me. But it would have to be at the right price.  For me that price is circa £1000.00 - and like to think this could be achievable within the next year looking at how the price has fallen over the last 20 months.  This could reduce battery payback time to 5.5 years based on our current usage. Although am mindful we are also chasing payback for original installation.

We have participated in the saving sessions over last couple winters (interested to see what this years grid support payment will be per kWh)

 I believe there are also beneficial TOU tariffs out there that could allow us to sell stored energy back to grid at better rate than 🐙 outgoing lite 8p per kWh  (they won’t give us normal outgoing 15p per kWh due to IO cheap charging rates)

also read TIM article about households
using batteries to save on TOU tariffs - interesting to read 43% of households with solar panels also have battery storage.

https://www.thisismoney.co.uk/money/bills/article-14011605/battery-storage-energy-bills-puredrive-duracell-solar.html

Would be grateful for any advice on here - thanks for reading this novel!! 😳

Swipe

Personally, I'd pay the extra 50p a day for 4 months of the year than spend money on an additional battery unless, as you say, you can get the cost down less than £1000.

SuzeQStan

That’s a very good point @Swipe - this is really
only an issue for the winter months so 50p daily cost shouldn’t apply for at least 6 months of the year.  Making ‘payback’ dates even worse unless we can game the battery

matt_drummer

SuzeQStan said:

 I believe there are also beneficial TOU tariffs out there that could allow us to sell stored energy back to grid at better rate than 🐙 outgoing lite 8p per kWh  (they won’t give us normal outgoing 15p per kWh due to IO cheap charging rates)

Interesting.

I moved to IOG from Cosy last week but still get outgoing at 15p

If I had to take 8p over the winter it wouldn't be a problem as we use all the generation, I'll just switch back to Cosy in the spring and then flip flop between IOG and Cosy as necessary.

I never discharge my batteries to the grid even though I could to make money, just not something I like doing, probably irrational!

I have enough batteries to get through four or five days with no solar living just off IOG.

I have a heat pump and two EV's although I don't charge mine at home. I just bought an EV for my wife so thought it was a good idea to get a charger at home. I charge my car at work for free and my wife's too when I can.

I'm not sure you can just install your own batteries, they need to be commissioned by a registered installer. I have GivEnergy and GroWatt, they both need registered installers as far as I know.

SuzeQStan

Thanks @matt_drummer - your home energy set up sounds brill. Did you get the dedicated charger in case your work charging is no longer free in future?

as regards adding battery / swapping out inverter/battery is supposedly straightforward although admittedly this needs more research now that you mention it.

 after reading a bit more on the forum about IOG I’ve gotten back in touch with 🐙 CS as I’ve got an email from them back in July 2024 stating we would only be eligible for Outgoing Lite 8p per kWh on IOG. 

 Am now querying this with them as it appears on their own website plus some forum threads that we should have been getting 15p per kWh.  At least I’ve got it in writing from them so should hopefully be able to claw back from our export from the summer if it does appear to be the case.

will be sure to update on here once 🐙 reply.

matt_drummer

I think my set up is OK but it was pricey!

But I didn't do it for purely financial reasons, I just wanted to prove to myself that I could get a house where I never actually give an energy company any money, and so far it works.

Of course, they give me money in the summer and then I use it in the winter, but over the course of a year they owe me.

My work charging will always be free for my car, and they really don't care about my wife's car either.

But I got the charger because I don't want to take advantage of their good nature too much and it is useful to have as a back up too. I also have to think about the range of my wife's car as she will never think about it.

So, for convenience really, also at a cost though.

I know I could granny charge but I don't like them. None of these are chargers, the charger is in the car, they are just fancy power supplies. Granny chargers aren't very fancy though.

Octopus never mentioned my export and had already automatically renewed at 15p for another twelve months at the beginning of October.

I could understand if they wanted to review it and I don't really care too much. I will just switch back in the spring as we import very little (almost nothing) between March and September. 

I do export a lot between March and September so would like to get the 15p if I can.

I think it will work, get paid 15p when I have an excess and buy for 7p when I need theirs.

SuzeQStan

Agree with you 100% about granny chargers - we melted a couple of plugs prior to getting our EV charger.  At minimum from safety perspective it’s a good idea

SuzeQStan

@matt_drummer -

Update: I’ve been advised today twice by 🐙 CS email that we were eligible for full Outgoing 15p flat rate the entire time we have been on Intelligent Go (since this spring when we got our EV charger installed by  🐙)

this is disappointing to read especially as it means we lost nearly 50% of our export value this summer as a result.

Ive got my original email from this summer to their CS asking if we qualified for the 15p outgoing export rate and have a reply from them stating we were not eligible and could only get ‘Outgojng Lite’ 8p export rate due to being on IOG.

we have requested recompense should be straightforward for them to calculate what the export payments should have been.

Will update any outcome

side note - we have decided against 2nd solar battery but will instead keep the funds earning interest towards the day a new battery is required hopefully long future date🤞🏻

matt_drummer

SuzeQStan said:

@matt_drummer -

Update: I’ve been advised today twice by 🐙 CS email that we were eligible for full Outgoing 15p flat rate the entire time we have been on Intelligent Go (since this spring when we got our EV charger installed by  🐙)

this is disappointing to read especially as it means we lost nearly 50% of our export value this summer as a result.

Ive got my original email from this summer to their CS asking if we qualified for the 15p outgoing export rate and have a reply from them stating we were not eligible and could only get ‘Outgojng Lite’ 8p export rate due to being on IOG.

we have requested recompense should be straightforward for them to calculate what the export payments should have been.

Will update any outcome

side note - we have decided against 2nd solar battery but will instead keep the funds earning interest towards the day a new battery is required hopefully long future date🤞🏻

Good news

SuzeQStan

Positive update: Octopus have credited us for the additional amount of export we would have gotten since May 2024 if we’d been placed on Octopus Outgoing 15p flat rate instead of Octopus Outgoing LIte 8p rate. 

I think this is mainly because their CS had advised us we weren’t eligible for the higher rate when I’d emailed to specifically ask back in July.

this is really good of them and they have also made a good will gesture payment on top.

mentioning this here in case anyone is on Octopus outgoing light export 8p rate - even if you are on octopus go (not intelligent octopus go) then you are still eligible for the higher 15p rate. Most of their smart tariffs are eligible for the higher rate now.

matt_drummer

SuzeQStan said:

Positive update: Octopus have credited us for the additional amount of export we would have gotten since May 2024 if we’d been placed on Octopus Outgoing 15p flat rate instead of Octopus Outgoing LIte 8p rate. 

I think this is mainly because their CS had advised us we weren’t eligible for the higher rate when I’d emailed to specifically ask back in July.

this is really good of them and they have also made a good will gesture payment on top.

mentioning this here in case anyone is on Octopus outgoing light export 8p rate - even if you are on octopus go (not intelligent octopus go) then you are still eligible for the higher 15p rate. Most of their smart tariffs are eligible for the higher rate now.

I saw their table today.

You are eligible for 15p Outgoing Octopus on IOG