On-grid domestic battery storage

zeupater

reeac wrote: »

... about once a year we lose our power due to fallen trees on power lines. A 5 kWh store would keep our freezers, fridges and lights going for a day or two without the noise of a standby generator.

Hi

In that case you'd need to have a system which can operate in 'islanding' mode which isn't likely to be a standard build feature, therefore a separate piece of controlling kit for most solutions ...

HTH
Z

Martyn1981

zeupater wrote: »

Hi

In that case you'd need to have a system which can operate in 'islanding' mode which isn't likely to be a standard build feature, therefore a separate piece of controlling kit for most solutions ...

HTH
Z

Most of the batts offer a dedicated socket to plug in during a powercut, but, and you can correct me here if I'm wrong, whilst a fridge or freezer may need say 100W, I have a feeling they can spike to 2kW or so for a second, which may exceed the output of the dedicated socket?

However, a multi gang charging phones, some torches and some LED lamps would be fine.

Martyn1981

Cut and paste, with some thoughts and observations:-

Electricity imported - 72kWh! (143kWh in July 2016)
Generated - 340kWh ( 333kWh in July 2016)
Battery discharge - 94.27kWh
ImmerSUN diversion - 69.29kWh (122kWh in July 2016)

A few observations to the above:
We were away on holiday for the last 10 days of July, so demand was low anyway, and as a result ImmerSUN demand and battery discharge required to cover demand in those last 10 days was reduced - 2.5kWh of battery discharge/day on average, essentially covering all quiescent house demand during night-time hours (makes you realise how much things like the fridge-freezer, wifi router etc all do still consume).

So have now avoided 581kWh of import with the battery now, which is more than £100 "saved".

It does add more data to the feeling that 4kWh is probably too small a size battery for my household overall as when we're at home it doesn't stretch out to cover the night-time draw from the fridge-freezer. One other thing I have noticed is that a lot of my import comes now from big ticket-items like the electric oven, and with the PowerVault being limited in its discharge to 1100W, it'll never cover that.

Martyn1981

Tesla Powerwall + High Electricity Prices Driving Australians To Energy Storage

According to Williams, only 2% or 3% of customers even asked about batteries prior to 2015. “Since adding Tesla Powerwall to our energy storage range, the volume of consumer enquiries for battery power and Powerwall specifically has grown to more than 95% of customers,” he told Gizmodo.

The introduction of the new and improved Powerwall 2 in October 2016 led to a further surge in demand. The new model features a built-in inverter, and it almost doubles the capacity of its predecessor, from 7 kWh to 14 kWh. As Australia’s average household electricity usage is estimated at around 16 kWh per day, the Powerwall 2 offers enough storage for many households to offset their entire electricity bills.

Some customers have done just that, and Chris Williams thinks this is just the beginning. “Mass adoption of residential and commercial batteries is already underway and considered to be the new norm,” he said. “Rarely do our customers enquire for just solar anymore, and battery power is the new must-have. Customers are [also] now commonly requesting items such as electric vehicle (EV) chargers with the intent of purchasing an electric vehicle in the future.”

JD800

Interesting to see how UK PV Installers push batteries over next few years. I had 8 quotes for my PV system (all including batteries initially as I asked for them). However, as some providers are pushing PV sales on "return on investment" and the potential battery savings are not included in FiT / savings calculations, the addition of a battery actually makes the ROI lower, or payback take longer.
As previous discussions on this thread indicate, domestic battery storage doesn't look cost effective at present, but if unscrupulous companies add "battery savings" at unrealistic levels and pessimistic electricity prices, then dodgy figures might make them appear cost effective and hence increase uptake.
For Mart / Zeup - final site survey on Friday but my measurements seem to indicate I can get 16 x 290 panels on my roof so a slightly bigger system than the original 4 kW one but small enough with a capping inverter to avoid needing DNO approval. Hopefully installation next week and get registered before end of Sep.

Martyn1981

JD800 wrote: »

For Mart / Zeup - final site survey on Friday but my measurements seem to indicate I can get 16 x 290 panels on my roof so a slightly bigger system than the original 4 kW one but small enough with a capping inverter to avoid needing DNO approval. Hopefully installation next week and get registered before end of Sep.

Boring Warning - That size set up sounds near perfect. Good gen means good sun, and good sun, means hot panels very quick, so rough rule of thumb don't expect to exceed approx 80% of rating on a warm sunny day (for long).

So inverter limit 3.68kW
16 x 0.29kWp x 80% = 3.712kW

JD800

You mean I might be wasting 0.032 kW some sunny days?

I didn't come on here for you to agree with me - fancy an argument on nuclear subsidies vs PV subsidies? :-)

Jim

zeupater

Hi All

Different but interesting analysis of Tesla's decision to seriously upsize the storage capacity for their Powerwall domestic battery.

Tesla Powerwall 2 - Business brilliance or a concept in need of a reality check ?

... a 14kWh Powerwall 2 simply provides unnecessary capacity. In summer a 14kWh system would almost exclusively operate in the 80%-100% capacity band and in the winter in a band between 0% & 30%. This effectively describes a solution which is over specified for energy efficient domestic properties, the very properties in which early adopters are likely to form a significant customer base ...

HTH
Z

zeupater

Hi All

Starting to see plenty of mention of 1KEA throwing it's hat into the domestic battery ring.

Not seen too much detail yet, but lots of what's out there seems to show sonnen battery pictures, which probably makes sense as the modern clean line design would fit alongside their in-store kitchen displays. The sonnen range also seems to offer a more appropriate entry point and scalability for energy conscious homes than Tesla's 14kWh Powerwall2 (see previous post above - #179) ...
https://www.sonnenbatterie.de/en-gb/sonnenbatterie

What does tend to irk me about much of what I've come across so far in both press and other publications is the tendency to not understand or convey the relationship between cost & storage capacity - for example ...

... says its solar and battery offerings will start from £3,000, depending on location, type of building, and ease of installation. That’s compared with more than £5,000 for a 14 kWh Tesla Powerwall. However, it's not hugely cheap: UK startup Powervault offers its own home battery product from £2,500.

Wired 1KEA battery article

"Tomatoes £3"... sorry, but when I go shopping I like to know how many and what quality tomatoes are being offered for £3 so that I can compare to other stalls ...

HTH
Z

Martyn1981

Lots of domestic storage news, but nothing major, just some small steps along the way:

1. Home battery safety - a while back I mentioned that there were concerns over fire risk from batteries, and that Australia was considering a rule requiring they be fitted outside in special enclosures. But not all Lithium batts are a fire risk, and not all batts are Lithium, so after consultation the report has been delayed as it's now felt the requirements go to far making it unfit for purpose.

So at least they are making sensible progress in putting together some guidelines.

Over 3,000 responses bring halt to Standards Australia’s ‘outdoor enclosures’ guidelines


2. Life expectancy and warranty lengths - In my calculations, which seem to fall short of being economical so far, I've stressed the point that I'm working on warranted life expectancy years/cycles. I know that's not fair, but till we know better, I personally don't want to bet £1,000's on life after warranty. So I'm hoping in the future to see something like 10,000 cycles and 15yrs.

So this article interested me, not so much the 'batts on the roof' idea, but the mention of a 20yr warranty on the batts, which bodes very well for the future, I think?

‘Microstorage’ solutions can enable 20-year warranties for lithium, JLM says


3. Batts are expensive, and returns on PV are getting tighter, so for new entrants, it may be some time before they can invest in PV and batts, and hope to breakeven.

So, EDF have an offering, that I think we've discussed before, where they install the PV for free, then charge you a lower than usual tariff for the leccy, about 10p/kWh. After 20yrs the PV system is yours.

Now, I wasn't that impressed before, as I pay EDF 12p/kWh for leccy, so if the PV system supplied half your leccy for an average house, that would be about 1,800kWh out of 3,600kWh, saving you 12p-10p = 2p x 1,800kWh = £36pa, with a 20yr lease on your roof, and locking you into a 20yr tariff deal with them too.

But ..... the latest offer includes batts too, and something I think is important an annual increase of "the retail prices index or 2.5% – whichever is lower." note 'whichever is lower', which doesn't sound too bad.

So perhaps 80% of your leccy, and you have PV and batts, assuming that's important to you, in order to take part in changing the way the UK gets/uses it's leccy.

I'm torn on this deal, but I do think it's a very interesting idea for those that don't believe they can afford a PV system.

Should homeowners warm to EDF Energy’s free solar panel system?

Of most interest to me (and possibly those on here with PV already) is that a scheme like this may drive up the installation rates of batts, and speed up the industry a bit.


So, all together, nothing too exciting for us, but hopefully some important steps on the way to affordable batts.