Tesla to unveil home storage batteries

groovyf

If anyone can shake up this market, Musk can...

http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/

WestonDave

Good Energy were supposed to be trialling a Maslow system - I applied to be part of the test but after a while the emails dried up and I've not heard anything for a while.

rogerblack

groovyf wrote: »

If anyone can shake up this market, Musk can...

http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/

Perhaps - getting to truly enormous scale so as to be able to integrate manufacturing for cost savings could be a great benefit.

Even 'normal' lithium-ion cells if operated to perhaps 80% maximum capacity in a cool environment last a long time - if you don't need to fast charge or discharge them.

EricMears

There was a bit about this on the BBC1 lunchtime news today.


But the 'test house' shown seemed only to have half a dozen solar panels & his battery cupboard looked just about big enough for a couple of car batteries. Nor was price mentioned.

Andy_WSM

The Tesla battery is £2.3k for a 10 kWh pack. You'd need a new inverter & Installation, so let's guess at £4k for the kit installed, maybe more.

I challenge anyone to prove this makes either financial or environmental sense to fit batteries on a PV system.

Ectophile

Andy_WSM wrote: »

The Tesla battery is £2.3k for a 10 kWh pack. You'd need a new inverter & Installation, so let's guess at £4k for the kit installed, maybe more.

I challenge anyone to prove this makes either financial or environmental sense to fit batteries on a PV system.

If we assume that electricity consumed in the evening is £0.16/unit, then the batteries hold about £1.60 worth of electricity.

If we assume a heavy user who uses all that every day, then that could be £500 per year saved.

Assuming your estimate of £4K for the complete upgrade is correct, the system could pay for itself in 8 years, and be saving £500/year for the rest of the life of the system (which has a 10 year guarantee).

That's no worse than a solar install in the first place. And if it's a new install, then the additional cost of the battery bank should be rather less than £4K, and the batteries could pay for themselves a lot quicker.

Of course, these figures only work if you have enough panels to fully charge the battery every day. That may be wishful thinking in a British winter. But Tesla will sell a cheaper 7kWh system.

As an added bonus, if you're in a rural area that suffers from power cuts, Tesla claim that the system can operate in islanded mode, allowing you to go completely off-grid if you need to.

So at the initial price, it's not a completely stupid idea. If the price later comes down, then it could become a must-have add on for any solar or wind system.

Martyn1981

Andy_WSM wrote: »

The Tesla battery is £2.3k for a 10 kWh pack. You'd need a new inverter & Installation, so let's guess at £4k for the kit installed, maybe more.

I challenge anyone to prove this makes either financial or environmental sense to fit batteries on a PV system.

And you'd win that challenge today, but the crucial date for all this, is tomorrow not today.

Just like PV itself (or home computers, mobile phones etc) batteries should fall in price both with technological advances and increased production. At some point in the future we may start to see problems with the amount of intermittent generation we have at specific times, such as PV on a sunny Sunday afternoon in June, or wind generation at night in the midst of winter. Perhaps in 15 years time ...... not sure.

Battery systems could take the excess PV for later use, or with clever integration be charged at night when excess wind is an issue (problem?) This would work in favour of the leccy generators and supply companies too, as it could help balance out price fluctuations. The supply companies pay variable prices for the leccy that they sell to us at fixed prices. So any opportunity to buy (and store) cheap leccy, or encourage reduced demand at peak times (perhaps encourage/subsidise some home battery systems, or even install some grid scale systems of their own) would work in their favour.

Environmentally, the argument is simple. Without storage, intermittent renewables can never reach their potential. Plus, even with the greatest will in the world, we'll still need gas to ramp up during peak times, so stored leccy could directly reduce some of that peak time need.

Yes, the storage cycle will mean a loss of approx 10%, so environmentally that is a loss, but the stored leccy (at higher demand times) should be shaving off the most carbon intensive generation as we move forward - we are already seeing a drop in coal generation and a move to gas. Plus a lot of coal generation gets shutdown during the summer, so perhaps storage could help to extend these periods by improving generation spread and predictability.

Like PV, to get to the cheap and cheerful future, we need to start somewhere, and that means an early and expensive start with batts. But hopefully, just like PV, it will only be a short painful period. There have been some suggestions that Tesla's 'Gigafactory' could lead to a halving of current Li-ion battery prices.

I appreciate that a lot of this is theoretical, but the economics seem to be moving too fast and favourably (at the moment) for PV plus storage not to happen in the near to medium term.

Mart.

Martyn1981

Andy_WSM wrote: »

I challenge anyone to prove this makes either financial or environmental sense to fit batteries on a PV system.

Just had another thought. You may have heard of EMMA (Energy & Micro-Generator Manager). This diverts excess generation to water heating, space heating etc. More recently diversion switches have stolen the news.

But the EMMA GVS (Grid Voltage Stabilisation) model can divert excess generation, and also throttle back generation to meet DNO requirements/restrictions placed on the PV (or wind, I think) install. It is approved by some DNO's.

This is a way of getting DNO approval for larger systems than they would otherwise accept. In simple terms, your export is capped, rather than your generation. Currently I think these are only installed on larger systems, but time will tell.

So ..... thinking ahead. If you were planning to go down this route, you might prefer to divert excess generation to battery storage, rather than to water/space heating.

Just a late night ponder. As you do!

Mart.

Andy_WSM

Ectophile wrote: »

So at the initial price, it's not a completely stupid idea. If the price later comes down, then it could become a must-have add on for any solar or wind system.

Completely stupid? No, definitely not. Financially viable - nope, not that either.

Taking your figures again at my confirmed TIC of 14p (& being in the SW we pay approx 10% more than those up North) reduces the viability somewhat - then there is the small factor of how to use 10kWh per day, every day throughout the life of the install. Any ideas? Then, as you say, there is also the consideration that some days a 4kWh PV installation will only generate a few kW at best during the Winter, so there is NO surplus at all to charge batteries with...

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.

Andy_WSM

Martyn1981 wrote: »

This is a way of getting DNO approval for larger systems than they would otherwise accept. In simple terms, your export is capped, rather than your generation. Currently I think these are only installed on larger systems, but time will tell.

So ..... thinking ahead. If you were planning to go down this route, you might prefer to divert excess generation to battery storage, rather than to water/space heating.

Just a late night ponder. As you do!

Mart.

Long term, that's the answer. A higher capacity system with priority to battery charging, then excess to water / space heating - assuming the property is on mains gas and able to heat that way otherwise there is no saving to be had either way is there?

It's not a completely stupid idea at all as Ectophile says. If new houses were built with these systems fitted and no grid connection then we'd go a long way to fixing an upcoming crisis. That won't happen though, will it, because pigs have their snouts in our energy trough and won't be happy when their feed stops being poured in...

1961Nick

Andy_WSM wrote: »

Completely stupid? No, definitely not. Financially viable - nope, not that either.

Taking your figures again at my confirmed TIC of 14p (& being in the SW we pay approx 10% more than those up North) reduces the viability somewhat - then there is the small factor of how to use 10kWh per day, every day throughout the life of the install. Any ideas? Then there is also the consideration that some days a 4kWh PV installation will only generate a few kW at best during the Winter, so there is NO surplus at all to charge batteries with...

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.

We'd probably have to factor in VAT on the battery as well taking the price towards £2800.

If battery prices did come down & there was a large take up, I can see export meters becoming compulsory when a battery is used.

Last year I exported 2053kWh. Sending all of this to a battery would have saved £220 & it would take 12.7 years to recover the cost of the battery alone. Factor in the cost of a new inverter, system losses, battery deterioration & I doubt you'd ever break even before the battery needed replacing.