Solar Battery Storage

Martyn1981

Exiled_Tyke wrote: »

If we assume that most 'on demand' electricity is (for the foreseeable future) to be met by gas turbines (being the only generation method with enough 'instant' capacity) then isn't your use of batteries green? In that, rather than adding to the off-peak supply of electricity (which presumably the aim will be to satisfy this need from nuclear and renewables) you are instead reducing peak-time demand in the use of less green power sources? Even though there is an efficiency loss in using batteries you are still reducing dependancy on fossil fuels which surely is a good thing?

Yes, but only once there is over supply. At the moment storing up 'my' leccy for the evening will reduce FF generation in the evening, but it will increase FF generation during 'my' generation as I'm no longer helping with grid supply.

Sorry if it sounds like a trick, but effectively I'm shifting FF generation around, and possibly increasing it, through system losses at the battery.

But, this only applies until wind, PV, wave, tidal etc etc creates oversupply, at that point shifting demand away from the evening peak, or shifting generation (via batts) to the evening peak will help reduce CO2 as that's the highest CO2/kWh period.

Hope that makes sense. I'm not against batts, they fascinate me, and I'd love a set, but there are a lot of factors to consider at the moment. But long term ...... all good news I think.

Mart.

EricMears

I'm not so sure that 'storing' E7 power for use in the day will offer quite the saving one might expect.


Both the storage an recovery will incur losses (and I'm really not sure what sort of efficiency either process will manage) so you'd certainly be paying more for 'stored E7' than 'actual E7.

Martyn1981

Some general news on battery storage, particularly from an Australian viewpoint as that is where deployment is gathering pace:-

Battery Storage: Incumbent Utilities Still Don’t Get It

“Cost-effective battery storage will be the game-changer, perhaps even independent of regulatory reform.”

Morgan Stanley is standing by its forecast from last May that 40 per cent of households may take-up battery storage by 2035. Indeed, it now believes that the take up rate – originally put at 2.4 million households by 2035, could exceed 3 million by the same date, although it says tariff and incentive reform will be key.

This accords with the broader view in the industry. Battery storage developers – such as Enphase – predict that storage costs will fall by half by 2020. Tesla suggests they may fall further.

And this article looking at trials and the benefits to the local grid too:-

Battery Storage Trial Shows Benefits To Both Consumers & Networks

On battery system costs, the trial found that these were “still generally uneconomic” at this time, even factoring in customer and network benefits.

But the rapid evolution of the technology meant that it was likely to become economic in the “near future,” either through the development of business models that unlock additional value, or through continuing technology cost reduction.

So the bad news is that we probably have to wait 5 years or more, but the good news is that we'll get to see the successes (and failures) first, and potential future consideration may coincide with the failure of our early inverters, giving us a chance to consider more encompassing upgrades.

Mart.

EricMears

Taking a break from cooking lunch to add this snippet of wisdom: As is pretty normal at this time of year, we keep having very bright intervals followed by duller ones. The duller ones are quite useful in that they let the panels cool off a bit before the next bright spell.

However, I'm also running the oven and a couple of rings all of which power up for a few seconds then off again when hot enough. Do these lulls & troughs coincide with dull & cloudy spells ? Do they heck ! :mad:

And for those who think I've drifted off topic : wouldn't it be handy to have a (fairly low capacity) battery to try and make the sunny spurts help out with the re-warming cycles ?

Martyn1981

EricMears wrote: »

And for those who think I've drifted off topic : wouldn't it be handy to have a (fairly low capacity) battery to try and make the sunny spurts help out with the re-warming cycles ?

I think you're describing load smoothing, and that's really important, especially to the grid and DNO's. The large supply side generators (wind and PV) can use a relatively small amount of storage to improve their supply to the grid, and I think it can improve the value they get.

Back to domestic, a few years ago I asked the battery experts on Navitron (some on-grid, some off-grid) about this. They always talk about battery cycles, and how many they should get and at what depth, and at what rate of discharge.

I asked about 'micro-cycles' (now nicknamed 'Mart's micro cycles') and whether these had an effect on battery life. The answer seemed to be no, shouldn't effect lifespan.

I think that's sort of what you are chatting about, perhaps gen fluctuating from 1kW to 3kW, and demand fluctuating from 1kW to 3kW, but all excess get's exported, and all shortfall gets imported. But a fairly small battery smoothing it out, would make a decent difference on a sunny/cloudy day.

The only issue perhaps, is your suggestion of a low capacity battery. That would do what you are suggesting, but might move away from my thoughts on micro-cycles, and therefore cause more battery wear, but normal battery wear.

This can throw up some interesting maths on deciding between a longer lasting bigger batt with smaller DoD. And a smaller batt, with lower investment costs, run at higher DOD but expected to die sooner. This is when it gets really complicated!

Mart.

Martyn1981

EricMears wrote: »

And for those who think I've drifted off topic : wouldn't it be handy to have a (fairly low capacity) battery to try and make the sunny spurts help out with the re-warming cycles ?

Nearly forgot, you are also moving into the area of capacitors, able to charge up, and discharge extremely quickly. I don't think they hold a charge for long, but ideal for what you describe.

Am I making this up? Are there some DIY tools that use capacitors? They take seconds to charge up, they don't last long, but no need to charge up beforehand, or to use regularly.

[Edit: Here we go, a 90sec charge screwdriver, good for 500,000 charges! I wonder if it lived up to expectations? M.]

Mart.

jbirch

I have solar panels - 12 in all - generates a bit over 3mWh per year. Installed in Nov 2011.

PV Solar UK - who installed it - are now offering a battery storage system. 12kW storage in four batteries - claims will cover almost all electricity.

Also say that can improve output of panels with new inverter, which comes with the system.

Cost - £5.5k which they say will pay for itself in c5 years.

While I am pleased with their panels, which have exceeded their estimates at the time, these numbers seem less likely - and all the more so from what I read here.

So - what do you all think?

Martyn1981

jbirch wrote: »

Cost - £5.5k which they say will pay for itself in c5 years.

To pay for itself in 5 years, then it has to save/earn you an additional £1.1k pa. You can't include current FiT/export earnings, as they are yours already.

So at best, in theory, you could save your current leccy bill (if you export more than you import) and switched to a no standing charge deal.

In reality you'll probably save more like £100 to £200 pa, and if the batts are on the inverter side of the TGM, then you'll also lose some FiT/export monies.

Assuming they are talking about an upgrade to a SolarEdge (or similar) system, then you may generate a bit more, if you have a little shading, but you'll need to think this bit over, how much do you generate against PVGIS targets now, could you get an extra 10% or so (300kWh pa). That could add £150 pa to the numbers, but even so, you're probably still looking, at best at around £200 to £300 pa.*

* £150 from SE system (FiT gains), plus £150 from leccy savings, minus £50 from battery losses (FiT losses).

Ask them to explain/justify the 5yr payback, but don't allow them to include any current FiT, export or leccy saving incomes.

Mart.

Sterlingtimes

Cardew wrote: »

The very thought of the heavily subsidised electricity you produce actually being fed to the Grid must be horrifying;)

That's where the electric patio heater helps. Quite useful on those not so warm spring afternoons.

tunnel

My local installer is offering 3 different brands of battery
The Tesla has 6.4kWh of storage followed by solaX with 5.8kWh and then Samsung with 3.24Kwh....all for the princely sum of £4.5k each installed.


May have to wait a bit longer afore I dip my toe in!!