Tesla to unveil home storage batteries

Martyn1981

Andy_WSM wrote: »

In fact, if you assume 50% export currently then you need to be producing 20kWh per day to have been able to divert 10 of those to the battery.

Bear in mind that this is being targeted at the US market. Their systems are, on average, a little bigger than ours, they have better generation, and they have higher leccy consumption.

For myself, I'd only need about 4kWh of useable storage, so a 5kWh Li-ion batt or perhaps 10kWh lead acid.

From that I could probably reduce my import by 1,000kWh pa*, so an annual saving of ~£140.

* Summer limited to import of approx 3kWh per day. Winter limited to export of approx 1 to 2kWh per day. Spring/Autumn by far the best, generation exceeds consumption, but import of 4 to 5kWh per day with fluctuating (cloudy) generation. So a rough average of ~3kWh per day.

As battery prices fall, a smaller battery pack, 10+ yr warranty, and integrated with a hybrid inverter (when my ESE inverters fail) then this could just work out for me.

But I still feel the bigger issue is the rounding out of the renewables package. Without viable storage intermittent generation will always be limited. Also consider peak demand periods on the grid. If 20% of houses had just 2kWh of storage, that would reduce peak demand by approx 5GW from 5pm to 7pm. Add that to the already reduced peak (more efficient lighting, tellys, fridge freezers, cooking) and there would be little difference between daytime demand and early evening.

Mart.

Andy_WSM

Martyn1981 wrote: »

Bear in mind that this is being targeted at the US market. Their systems are, on average, a little bigger than ours, they have better generation, and they have higher leccy consumption.

For myself, I'd only need about 4kWh of useable storage, so a 5kWh Li-ion batt or perhaps 10kWh lead acid.

From that I could probably reduce my import by 1,000kWh pa*, so an annual saving of ~£140.

* Summer limited to import of approx 3kWh per day. Winter limited to export of approx 1 to 2kWh per day. Spring/Autumn by far the best, generation exceeds consumption, but import of 4 to 5kWh per day with fluctuating (cloudy) generation. So a rough average of ~3kWh per day.

As battery prices fall, a smaller battery pack, 10+ yr warranty, and integrated with a hybrid inverter (when my ESE inverters fail) then this could just work out for me.

But I still feel the bigger issue is the rounding out of the renewables package. Without viable storage intermittent generation will always be limited. Also consider peak demand periods on the grid. If 20% of houses had just 2kWh of storage, that would reduce peak demand by approx 5GW from 5pm to 7pm. Add that to the already reduced peak (more efficient lighting, tellys, fridge freezers, cooking) and there would be little difference between daytime demand and early evening.

Mart.

If the UK keeps building houses at the rate it is and not building new infrastructure, then something like this could be the saviour for our grid.

It's early days yet, but it's good that Tesla have made a break into the market as it will encourage others to do the same.

Sterlingtimes

Perhaps, convert to Economy 7 for cheaper electricity at night. Charge the batteries at night and use them to supplement any inadequacies in solar production during the day. Counter productive, of course. It is all a matter of time shifting. But isn't time shifting better managed by a smart grid? I am far from convinced that for UK towns and cities this is the best method of managing electricity. Presumably, batteries would not be deployed industrially by electricity distributors.

Martyn1981

Andy_WSM wrote: »

If the UK keeps building houses at the rate it is and not building new infrastructure, then something like this could be the saviour for our grid.

It's early days yet, but it's good that Tesla have made a break into the market as it will encourage others to do the same.

That's what I'm thinking.

It's actually unfair that Tesla is getting so much press time/coverage since these products already exist (SMA, Nedap PowerRouter etc), and are available in a single package - PV inverter, charge controller and battery. Also, as you'll know from reading Navitron threads, there's nothing new about the idea of integrating domestic generation with battery storage. The off-grid folk have been doing it for decades, though I'd rather have a no maintenance Lithium set-up to a lead acid system that needs maintenance and safety concerns if enclosed, such as hydrogen gas venting.

But .... I'll admit to being very excited about this announcement. I waited impatiently all week and nearly stayed up to watch it live, but opted for an early rise and a good read instead (hence my early post on the PV News thread).

The reason I got excited is that Elon Musk has a way of getting press attention as he seems to recognise markets before others. He was quick to get into web software development, internet payments, private space technology, Tesla Ev's, SolarCity PV. Doesn't mean he's right, but you wouldn't want to bet against him.

This move is very clever, for EV's to get cheaper he needs increased demand to increase supply of batteries to bring down their price. The exact same applies to home battery storage, and by sharing common technology ...... 2 birds, 1 stone. Or perhaps 3 birds, since he's building the world's largest Li-ion battery plant.

Must be clear, I'm not disagreeing with your current assumptions. On the PV news thread I listed 3 articles, but the only line I quoted was:

"I don't believe this product in its first incarnation will be interesting to the average person," conceded Peter Rive, SolarCity's chief technology officer.

which I think is a fair and honest comment today. But the potential for tomorrow has certainly received a boost, even if it's only by stealing media attention.

I also think these announcements are important to help combat those Ostriches that like to look at renewables one product at a time, and point out what they can't do, rather than look at a fully integrated package (wind, solar, biomass, hydro, tidal, wave ...... storage).

Lastly (sigh of relief all round), if we look optimistically at costs:
convert to pounds (no premium)
half cost for a 5kWh system (my needs)
half cost for price reductions in 5 years,
then $3,500 today for 10kWh becomes £600 for 5kWh tomorrow(ish).

That doesn't sound too bad. Probably over-optimistic, but these technologies do seem to surprise as they move from the fringes to established.

Mart.

Martyn1981

Sterlingtimes wrote: »

Presumably, batteries would not be deployed industrially by electricity distributors.

They might be deployed. Powerpack (the big brother of the Tesla Powerwall product) comes in 100kWh installments. It's being touted for MWh deployment by large consumers of leccy, and for leccy suppliers to help reduce their peak time costs when leccy spot prices can rise massively.

But again, we're looking forward quite some way.

Mart.

EricMears

Martyn1981 wrote: »

half cost for price reductions in 5 years

Every chance of a rather bigger reduction than that !

If I were to fit another SP system just like mine in a couple of months time, I'd expect it to be around a third of the cost that it was 4 years ago. And of course that would include scaffolding, labour etc which would have gone up rather than down so current panel prices are very likely less than a quarter of the cost of mine.

Similar sort of price reductions apply to any new technology becoming mass market items - e.g. early colour TV sets were several hundreds of pounds fifty years ago (when £100 was worth a £100 - adjusting for inflation that's probably several thousand now !)

Martyn1981

EricMears wrote: »

Similar sort of price reductions apply to any new technology becoming mass market items - e.g. early colour TV sets were several hundreds of pounds fifty years ago (when £100 was worth a £100 - adjusting for inflation that's probably several thousand now !)

Good point, I didn't want to be too optimistic as battery technology isn't new, though it's being improved all the time. But applying the same argument to PV (it wasn't new, just needed support) even the most enthusiastic (myself included) never expected prices to fall as fast as they have.

Apologies for going off on a tangent, but many might not realise just how far ahead of expectations we currently are. When FiTs was first launched the critics only focused on the initial subsidy rate and ignored the built in degression, but only five years in, we are probably 10 years ahead of schedule as we shattered the 2020/21 rate in August 2012:

current FiT rate 13.39p* for 20 years
original planned FiT rate for 2015/16 30.2p for 25 years
original planned FiT rate for 2020/21 18.8p for 25 years

* Can't find any news articles, but it looks like the degression point (100MWp+) for the last qtr must have been reached as OFGEM are now showing a FiT rate of 12.92p from 1st July 2015.

Mart.

System

Think laterally. I looked carefully at my pattern of car usage and I concluded that the purchase of an EV made complete sense. Putting PV solar to one side for the moment, my annual savings on road tax, fuel and insurance will amount to about £850 per year. The car is only serviced once every 2 years. What I failed to factor in was the ability to charge the car from my PV Solar when the sun is out. Last month, I drove nearly 360 miles and my total electricity cost was about £1.23 for the month. This works for us as I am retired, and the cost of the battery is paid for as part of the cost of the car. 360 miles range equates to about 85kWhs of electricity or a further saving of about £9 on my 'fuel' bill compared to having to charge at the standard kWh unit price.

Sterlingtimes

Hengus wrote: »

Think laterally. I looked carefully at my pattern of car usage and I concluded that the purchase of an EV made complete sense.

Interesting. What was the difference between the price of your car and the nearest petrol equivalent? It could suit me since I live 6 miles from work but use company funded transport for business purposes.

lordgarner

Could MSE create a calculator that enables people to determine if it would be economic to install home batteries enough to store a complete days electricity, charged by Economy 7 or better, than to use normal tariff electricity. Obviously all costs need to be included, capital costs, installation etc.

Not having solar panels nor the ability to install them as I live in a flat, i would like to determine if the Economy 7/Tesla battery combination has a pay back period that I would consider.

Also would it be practical to take my system to a new home?