On-grid domestic battery storage

mmmmikey

Reed_Richards wrote: »

My electricity usage has dropped to about 1.3 kWh per day since I had my PV + battery system installed at the beginning of March. I am wondering if I should switch my energy supplier to one that offers a zero standing charge tariff. What has everyone else done?

Hi


I'd agree with the "put your estimates into Uswitch" approach and see what it comes out with. Just one observation - you may well find that you use a fair bit more in the winter, so it might be worth trying a couple of "what if" scenarios - e.g. assume you use 2kWh or 3kWh per day and see if the zero tariff still comes out cheaper, or at least not massively more expensive. Then you can balance the benefit of the best possible tarriff with the risk of being a bit under in your estimates.


My PowerVault developed a fault under full load, no problem getting it fixed but I've been away for a couple of days. Itching to get started again


Good luck, Mike

Reed_Richards

zeupater wrote: »

... and you're asking because you're paying more in standing charge than electricity?

Yes

zeupater wrote: »

... what about gas? ... what about dual fuel discount etc? ...

I live in a village without a mains gas supply so no dual-fuel for me.

mmmmikey wrote: »

Hi
- you may well find that you use a fair bit more in the winter, so it might be worth trying a couple of "what if" scenarios

Good point but I see no reason why, in principle, I cannot switch suppliers between summer and winter.

zeupater

Reed_Richards wrote: »

Yes

I live in a village without a mains gas supply so no dual-fuel for me.


Good point but I see no reason why, in principle, I cannot switch suppliers between summer and winter.

Hi

If ZSC works for us at ~3.5kWh/day import then it should for you at below that ... just feed your estimate into a comparison site & see what pops up, but, as mentioned, just be careful to not underestimate your overall annual demand!

HTH
Z

Reed_Richards

Sorry, ZSC stands for??

Coastalwatch

Could it be Zero Standing Charge?

mmmmikey

Hi - on the subject of tarriff's, solar and batteries, Economy 7 can be worth considering (depending on usage) as the higher day time rates can be offset through the use of solar pv and battery storage.....

1. E7 tarriff means cheap rate electricity overnight until sunrise

2. Solar panels means cheap electricity (possibly free on a good day) from sunrise to sundown - the battery could fill in the odd patch where a cloud goes over and for most of the year still end the day fully charged for some users (i.e. although the day rate is higher you may not need to import much)

3. Suitably sized and fully charged battery means cheap electricity (possibly free on a good day) from sundown to E7 start (again, still higher day rate but you might not need to import much)

It's a no-brainer for me because I have night storage heaters and even without the battery have achieved 87.5% night / 12.5% day split through low daytime usage and daytime import reduced by the solar PV. Other than running the washing machine overnight and charging the lawnmower and eBike batteries via a timeswitch I haven't done anything special to shift my demand.

The case would be less compelling without storage heaters, but still worth checking - be intersted to know if anyone's done this? I'd be surprised if this would be a good option if you're in zero standing charge usage territory but haven't checked this.

For info, my new E7 tarriff is EDF Easy Online Exclusive May20 and the rates are day: 19.81p / kWh; night: 4.7p / kWh; standing charge: 21.97p / day. If the battery works as expected I will be buying 98% of my electricity at 4.7p / kWh - even less than the FIT export rate! I'll soon be saving so much I won't know what to do with the extra cash.....

Thanks for your post Reed, which prompted me to check rates

Reed_Richards

mmmmikey wrote: »

The case would be less compelling without storage heaters, but still worth checking - be intersted to know if anyone's done this?

Provided it has been a reasonably sunny day then my battery will have enough charge to get me though the hours of the E7 tariff. The worst time is cooking in the evening when the battery alone cannot supply enough power or if, as today, my wife waits for a cloudy day then decides to wash everything she can find (dishes clothes etc.).

JKenH

Reed_Richards wrote: »

Provided it has been a reasonably sunny day then my battery will have enough charge to get me though the hours of the E7 tariff. The worst time is cooking in the evening when the battery alone cannot supply enough power or if, as today, my wife waits for a cloudy day then decides to wash everything she can find (dishes clothes etc.).

Sunny days find my wife in the garden. On a dull or wet day she will wash, iron, vacuum and demand heating. When I explain how unreasonable she is being she suggests I might like to do the washing, ironing etc at which stage I slink into the garage and switch on all the fluorescent lights.

Reed_Richards

mmmmikey wrote: »

It's a no-brainer for me because I have night storage heaters and even without the battery have achieved 87.5% night / 12.5% day split through low daytime usage and daytime import reduced by the solar PV.

Can you not improve on this by using spare power from the solar PV to fully charge the storage heaters? So that on a good sunny day they become day storage heaters rather than night storage heaters? Or does the tariff work out so you get more money exporting your spare power during the day than you pay to get power back at night?

mmmmikey wrote: »

Thanks for your post Reed, which prompted me to check rates

Glad to help.

orrery

mmmmikey wrote: »

....Economy 7 can be worth considering (depending on usage) as the higher day time rates can be offset through the use of solar pv and battery storage.....
The case would be less compelling without storage heaters, but still worth checking - be intersted to know if anyone's done this?

I agree about E7 and PV.

I have 4kWp PV but no batteries or storage heaters. I'm on E7 and use it to charge an electric car. We use washing machine and dishwasher overnight (and my beer fridge on a timer to run only during E7 and solar hours). We don't run the tumble dryer in the same way - we've installed one of these devices, specifically optimised for outdoor usage, powered by both solar and wind, for drying clothes.

It was about evens when I switched to E7 - no real advantage but no loss. It certainly wouldn't work for me without storage heaters or an EV to charge.