Solar PV with or without battery?

QrizB

pensionpawn said:

However if you buy a battery based on a tariff like Flux and that tariff is withdrawn, or changed in a way that no longer benefits, what then? Well you're back to just avoiding random imports, which may have a very long RoI...

There was a very agitated poster on the main Energy forum a few weeks ago, ranting that he'd bought a Powerwall and it was unfair for Octopus to withdraw the Tesla tariff. Claimed it had ruined his ROI.

Edit to add: this thread:

https://forums.moneysavingexpert.com/discussion/6468196/why-am-i-still-having-to-pay-a-electricity-standing-charge-when-i-export-more-than-i-import

Second edit: no, sorry, it was this thread:

https://forums.moneysavingexpert.com/discussion/6468701/solar-panel-export-rates-and-fixed-standing-charge-costs

(Apologies for the confusion, there's been a bit of a theme of this recently!)

pensionpawn

QrizB said:

pensionpawn said:

However if you buy a battery based on a tariff like Flux and that tariff is withdrawn, or changed in a way that no longer benefits, what then? Well you're back to just avoiding random imports, which may have a very long RoI...

There was a very agitated poster on the main Energy forum a few weeks ago, ranting that he'd bought a Powerwall and it was unfair for Octopus to withdraw the Tesla tariff. Claimed it had ruined his ROI.

I believe that a battery with 4 wheels and a bi-direction charger is the way to go, literally!

Reed_Richards

pensionpawn said:

....I agree, the advent of Flux is now cleverly moving the primary use of batteries from just avoiding random imports firmly into the function of skewing energy demand away from the current daily peak. Quite sensible from a national energy dimensioning / balancing point of view, especially through winter. However if you buy a battery based on a tariff like Flux and that tariff is withdrawn, or changed in a way that no longer benefits, what then? Well you're back to just avoiding random imports, which may have a very long RoI...

.... but the argument being put forward for not buying a battery is that you can make so much money from export using a tariff like Flux! 

If you could sell electricity for the same price you buy it there is no economic case for having a battery - but you can't do this.  If you can only get a measly 4p per kWh for your exported electricity whilst having to pay 29p per kWh to import it (as could be the case with some providers at present) then the economic case for having a battery is much stronger.  Flux places you somewhere in between these two extremes so if it was withdrawn you might well end up with a stronger economic case for having a battery than there is at the moment.  

Screwdriva

Agreed. Flux has weakened the case for battery. 

That said, assuming bi directional chargers take off, a battery may prove to be an indulgence more than a necessity. 

pensionpawn

Reed_Richards said:

pensionpawn said:

....I agree, the advent of Flux is now cleverly moving the primary use of batteries from just avoiding random imports firmly into the function of skewing energy demand away from the current daily peak. Quite sensible from a national energy dimensioning / balancing point of view, especially through winter. However if you buy a battery based on a tariff like Flux and that tariff is withdrawn, or changed in a way that no longer benefits, what then? Well you're back to just avoiding random imports, which may have a very long RoI...

.... but the argument being put forward for not buying a battery is that you can make so much money from export using a tariff like Flux! 

If you could sell electricity for the same price you buy it there is no economic case for having a battery - but you can't do this.  If you can only get a measly 4p per kWh for your exported electricity whilst having to pay 29p per kWh to import it (as could be the case with some providers at present) then the economic case for having a battery is much stronger.  Flux places you somewhere in between these two extremes so if it was withdrawn you might well end up with a stronger economic case for having a battery than there is at the moment.  

Those who have a battery and DNO approval to export 6 kWs could theoretically get paid 13.23p (max export - min import) x 18 kWhrs (before battery loses) = £2.38 / day (~£870 pa). They see this as a good earner (not for me...) however they of course will have to repay the initial investment cost and take account of the impact of the degradation this level of electrical work will cause. I agree with you that net metering would be ideal however the demand profile complicates the fiscal accounting. Flux is sufficient for me until bi-directional car chargers become a) available and b) fiscally attractive. What are the chances in future of the DNO approving export values appropriate to car battery sizes....? Loads of changes / flux (couldn't resist) in the electricity supply / demand industry over the next 20 years!

pensionpawn

Screwdriva said:

Agreed. Flux has weakened the case for battery. 

That said, assuming bi directional chargers take off, a battery may prove to be an indulgence more than a necessity. 

Looks tempting as is their latest inverters with "island mode", which is certainly a replacement for my existing SolarEdge inverter, when it goes pop.

1961Nick

I still think there's a case for a small battery operating in the 4pm to 7pm peak rate window. With careful planning the ROI could be £300pa after round trip losses. A 5kWh battery costs around £1500 & fitted with a new install doesn't require an additional inverter. It would also negate the need to load shift & provide an EPS.

Reed_Richards

Screwdriva said:

Agreed. Flux has weakened the case for battery. 

It's a lot more complicated than that.  Any tariff that allows you to buy electricity cheaply at one time then sell it for more money at another time (or simply use it when electricity is more expensive) gives you a case for having a battery.  Flux is that type of tariff.  Any tariff that lets you sell your solar electricity as you generate it for a price not too far off what you pay for it diminishes the case for a battery.  Flux is that sort of tariff too.    

UncleK

We are all electric (GSHP and UFH) and our batteries have saved us loads, particularly as we charge them up on cheap rate in the winter nights and use that in the day. Even in the dead of winter, 2/3rds of our electricity is bought at cheap rate even though it's only available for 1/3rd of the time. Like I say, not directly applicable but thought I'd share anyway.

pensionpawn

1961Nick said:

I still think there's a case for a small battery operating in the 4pm to 7pm peak rate window. With careful planning the ROI could be £300pa after round trip losses. A 5kWh battery costs around £1500 & fitted with a new install doesn't require an additional inverter. It would also negate the need to load shift & provide an EPS.

As an add on to an existing system a 5 kWhr GiveEnergy hybrid inverter battery is just short of £2k (inc VaT). So that's 5 kWhrs a day at 13.23p which is roughly £240 pa, giving a RoI of ~ 8 years (5 with your numbers)! That's of course if Flux like tariffs don't vanish / become uneconomical over that time period. Horses for courses, however I've played my waiting game once, 7.25 years for my original install to RoI. I'll sit this one out as I prefer to pay to be in control and not be held hostage to market forces.