@old_scientist Another point I might have made a little more clearly is that I put ‘consumption’ for 2025 as this figure includes some 600+ kWh used just to charge battery on each of the 30 days and without this battery charging, my actual consumption was ~450 kWh or less. It will be very interesting to see how your figures pan out over the more favourable summer months. Regards, Toodles.

Posted by: @toodles

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@old_scientist Another point I might have made a little more clearly is that I put ‘consumption’ for 2025 as this figure includes some 600+ kWh used just to charge battery on each of the 30 days and without this battery charging, my actual consumption was ~450 kWh or less. It will be very interesting to see how your figures pan out over the more favourable summer months. Regards, Toodles.

@toodles Indeed. On a tariff such as IOF where import and export prices are the same, the only thing that really matters is the difference between consumption and generation, i.e what is the net export for the period. Due to round trip losses, I grant it will be more efficient if there were less grid charging and more solar charging or the battery, but that is more than offset by the fact that you've dumped your battery at peak rate (29.8p) in the first place.

Our summer usage is ~10-12kWh per day. Our generation with the extra solar panels should be 10-50kWh/day (50kWh on a perfect cloud free mid-summer day).

Looking at my own numbers for the first half of summer (April - June), we would have been around £45-50 better off had we been on IOF, and that's without exporting 10kWh per day at peak rate. Extrapolate that to be around £100 for the 6 month period April to September, and then factor in we are also doubling our solar capacity, all of which will be exported at 22.36p giving maybe another £500 plus, and I think we'll have £600 in credit to carry into winter (although not this winter). With the additional solar generation in winter, I'm hoping we will be very close to being net zero cost for the year.

The other aspect I like of combining IOF in summer with Cosy in winter is that every kWh we export in summer (at 22.36p) buys us back 1.5kWh of heat in winter (at 12.91p and allowing for 15% round trip losses), or 2kWh heat in winter for exporting at peak rate (29.82p) in summer (based on current rates). That really does incentivise us to minimise our usage in summer to maximise our budget for winter.

@old_scientist I am attaching the consumption and solar production figures in kWh and in monetary value for last year. Cosy tariff applied along with Outgoing fixed for the export for most if not all the time. (I would need to go back through my bills to be sure.) Regards, Toodles.

Are there any new kWh rates out at the moment?

We don’t have solar pv so we don’t have to worry about import/export. Just electric purchase price.

4 bed, 18c house  with solar hot water.

Our total 12 month consumption was 5602kwh…

est breakdown is 2468 kWh for heat pump

and 3134 kWh for all other elec. no gas, no wood burner.

We are on a 19p per unit rate and when I did the math on a comparison with 15p/23p with Ovo we were more or less level on cost without the yoke of avoiding peak usage or trying to cram in consumption in a narrow time band. Also - is that the most efficient way to use a heat pump?

Where is the low hassle low cost supplier?  Any thoughts?

@sunandair Without battery storage, I am not sure that OE’s Cosy would provide any benefit, but here are the rates in my area (SE). Regards, Toodles.

Thanks Toodles…

I've been on Octopus Agile for the last couple months. It's a dynamic tariff for those with a smart meter and the pricing changes every 30mins. I've been able to achieve a net import price below 15p for the last couple of months, but you do need to be able and prepared to load shift to the cheaper times to take full advantage.

I’m guessing it’s been a bumper crop for surplus solar the past 3 months.. do you have any experience of agile when it’s cloudy or dull?

local household exporters near me seem to be complaining earlier in the year about agile rates for a short time but that might be just hearsay.

It sounds like it’s worth a closer look. Thanks.

Posted by: @sunandair

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I’m guessing it’s been a bumper crop for surplus solar the past 3 months.. do you have any experience of agile when it’s cloudy or dull?

local household exporters near me seem to be complaining earlier in the year about agile rates for a short time but that might be just hearsay.

It sounds like it’s worth a closer look. Thanks.

I've been on Agile import for coming up to two years. The key to getting the best from it is to go all-in with your home automation so that you can ensure you're not pulling from grid at the expensive times (particularly the 4pm - 7pm stretch). To be frank, that has a far bigger effect than whether it's sunny or cloudy. The other big one is, if you have an EV, making best use of the times of negative pricing.

I've just gone through a quick exercise in working out average cost per unit and, during the time I've been on Agile import, it has worked out at an average of 21p/kWh. That is excluding standing charge and including the Vodka and Tonic. My average export price for the same time period is 13p/kWh. What it does not, however, show, is the extent to which my import consumption has dropped as a result of the home automations.

It's easy to complain about prices in the short term but the longer term trends can say a different story.