On-grid domestic battery storage

EricMears

duckvader wrote: »

Hi All,
I'm new to this forum, I am also new to solar and battery storage so am looking for some advice.
I have got a brand new BMW i3 92ah 33kWh battery available to me FOC.
I have been thinking about solar panels for quite a while now and would like to use the battery with solar panels. I think I can fit 10 panels on the roof.
BMW have started using these batteries in a Tesla powerwall type set up but I can't find any info on it.
My concern is that the battery is controlled by BUS messages from the cars electronics.
What do you think?

There's a lot to be said for fitting solar panels on the roof. An electric car is a great idea (esp if you've persuaded someone else to pay for it !).

I have both SPs & a BEV though I can't really say that they work together all that well. I like to start each day with the car battery fully charged so would be able to drive off when the fancy takes me. The SPs never really produce enough to charge the car before (say) 11am and would never get anywhere near supplying the 16A (4kW) my car would accept since the panels are only 4kWp and I want to use the 'free' electricity for other things.

I have occasionally charged the car during the day when there were no other major calls on the available power but have to throttle it back to 10A (2.4kW) to avoid buying any power.

On the whole, I'm much happier to charge overnight on E7 and the saving I could make by regular daytime charging really isn't that significant.


I seem to have misunderstood duckvader ! I thought he had the car but it seems it's just the battery !

Martyn1981

duckvader wrote: »

Hi All,

I have got a brand new BMW i3 92ah 33kWh battery available to me FOC.

What do you think?

Hiya and welcome. I've seen a detailed build of a 20kWh battery system using the cells from a 24kWh Leaf (written off). The build is explained (with pics) on the Navitron forum see post #20 onwards.

There are also a few blog videos on Youtube of people building 'DIY Powerwalls'.

duckvader

Thanks for the replys guys, I'll take a look.

Martyn1981

Good news:

Residential storage secures tax break when sold with solar panels

The Solar Trade Association (STA) today (3 August 2017) announced that it has secured a 5% rate of VAT on battery storage instead of the standard 20% currently applied. However, in order for HMRC to allow the lower rate to apply the battery has to be sold and installed alongside solar, which already benefits from the lower rate.

Bad news:

“This is on the understanding the battery is linked to the solar panels and ancillary to the supply of the solar panels. We would expect the aim to be one of maximising use of on-site solar power consumption,” the note states.

It adds that if batteries are sold separately and retrofitted to existing solar systems, this would be seen as a “standard rated supply” and therefore does not qualify for the tax break.

The differentiation seems a bit daft. If the government wants to encourage storage, and specifically storage of renewable PV generation, then why does it matter if the battery is a retro-fit.

Martyn1981

Italian region of Lombardia launches €4 million incentive program for solar storage

The scheme has a budget of €4 million and provides rebates of up to €3,000 that may cover up to 50% of the costs for buying and deploying the storage system.

Reminds me of a suggestion by our very own Z for a 50% subsidy or approx £3,000 on a PWII.

Is Big Brother watching us, and if so, is he Italian. :think:

zeupater

Martyn1981 wrote: »

... Reminds me of a suggestion by our very own Z for a 50% subsidy or approx £3,000 on a PWII.

Is Big Brother watching us, and if so, is he Italian. :think:

Hi

... "It was a bright cold day in April, and the clocks were striking thirteen ...." must have something to do with it - lots of sun and the Civil Servants at Ofgem & BEIS would be on their lunch-break, totally missing the fact that the clock is broken and needs fixing ... 'back to work in a couple of hours guys, there no need to rush - we know you don't like change much so shuffle the pages around again, just like yesterday ... and the day before, and the day ...." ..... doubt it's anything to do with cross border spy networks, it's probably just a case that the Italian's don't allow brain dead jobsworths anywhere near their version of an energy regulator, and definitely not the cobweb ridden strategy room at the back of the Whitehall broom cupboard ... :cool:;)

HTH
Z

Ectophile

I Got an email today from E-ON, plugging their latest solar options, including batteries: https://www.eonsolar.co.uk/products

Lots of pretty graphics on the web site, but precious little information on the costs.

mmmmikey

Been looking into Powervault and like others here have concluded it needs to halve in price to be reasonably worthwhile. Can I throw a couple of thoughts into the pot for consideration?

1. According to my rough and ready calculations the batteries only account for 40% or so of the 4kWh Powervault. So even if batteries were free the cost of the electronics would still make the economics questionable.
2. How efficient would the storage need to be and/or what would a smart tariff need to look like to make it worth storing cheaper night time electricity for use in the day and what does this mean for grid loading, i.e. is this ever going to be a realistic option?
3. On a slightly different note, how about buying a 200ah lead acid battery, high powered charger and small inverter to provide about 1kWh of storage for a few hundred quid, to provide load for low power background stuff? Is there an electronic device you could buy to control this automatically?

Just thinking out loud, instinctively battery storage sounds like a good idea but challenging to make the economics work.....

silverwhistle

mmmmikey wrote: »

Just thinking out loud, instinctively battery storage sounds like a good idea but challenging to make the economics work.....

Let us know how you get on. My minimum usage is 52 watts, and a bit more when the refrigeration kicks in so it would be nice to cover that!

Martyn1981

mmmmikey wrote: »

1. According to my rough and ready calculations the batteries only account for 40% or so of the 4kWh Powervault. So even if batteries were free the cost of the electronics would still make the economics questionable.

You're probably right about the percentage for the batts, and the BOS (balance of system) costs.

My thinking is that the cost of the 'package' and the cost of install, will fall as numbers go up, though we may need to see some consolidation in battery products, as there are a lot of offerings at the moment competing for very little demand.

So BOS should come down rapidly, as and when (or even if) demand rises high enough. Some of that demand will be natural as per Hawaii, Australia and locations with particularly high leccy unit costs, but elsewhere it may require an artificial boost, as per Germany, Sweden and now Italy.

I still have 2020 in my head as a date when all of this should make more sense, we really are right at the start of domestic rollout.