What to do with Excess/Cheap Power?

[Nick Thomas]

14 hours ago, puntloos said:

As in, is any cooling I put into that room (at 300% efficiency) more value for my kwh than seling it to octopus?

 

I woke up this morning thinking that the 300% efficiency thing is a bit of a red herring here ^^.

 

If you export at 25p (peak) in summer, then buy at regular prices in winter (again ~25p) to put into your heat pump, it still gets the CoP boost - it ends up being the same number of kWh of heating or cooling, the only difference is that you actually need the heating in winter, whereas the cooling in summer is marginal at best.

 

If your export is at the regular 15p in summer, then importing at 25 or even 35p (peak) in winter, then you take a loss - but it's 50%ish, rather than 300%.

 

 

 

[Marvin]

On 01/06/2024 at 18:17, MikeSharp01 said:

Can we know more about what this comprises - bikes, scooters, rodeo simulators......

Err... mobility scooters

[puntloos]

On 02/06/2024 at 10:46, Nick Thomas said:

 

I woke up this morning thinking that the 300% efficiency thing is a bit of a red herring here ^^.

 

If you export at 25p (peak) in summer, then buy at regular prices in winter (again ~25p) to put into your heat pump, it still gets the CoP boost - it ends up being the same number of kWh of heating or cooling, the only difference is that you actually need the heating in winter, whereas the cooling in summer is marginal at best.

 

If your export is at the regular 15p in summer, then importing at 25 or even 35p (peak) in winter, then you take a loss - but it's 50%ish, rather than 300%.

 

 

Certainly a fair point - of course I don't know what losses are involved when importing/exporting. Is a kwh exported truly a kwh? Assuming 25p important and export, is the grid a 'temporal' battery?

 

I suppose in the end it is all about losses. If you keep your house "closed" and any losses are at least as good as they get through your amazing airtightness and U-values then it doesn't matter too much when you put it into the house. My problem is that if anything my house is overheating somewhat so cooling in summer doesn't seem like a terrible idea. 

[gc100]

How do you all control the flow of electricity from inverter to HW, ASHP, etc when you are generating excess power? What control unit do use ?

[Andehh]

I just manually turn on the ASHP when the sun is really out, especially if it coincides with our cheap afternoon Octopus Cosy tariff.

[Nick Thomas]

On 08/06/2024 at 23:13, puntloos said:

I don't know what losses are involved when importing/exporting. Is a kwh exported truly a kwh? Assuming 25p important and export, is the grid a 'temporal' battery?

 

I'm not up on the logistics of it all, but export is measured at the meter in your house, not out in the grid somewhere, so I'd imagine the scope for losses is pretty minimal. Going through the inverter has an efficiency cost, but that's small - and paid whether you're using it locally or exporting it. Battery storage does imply some loss - I think the peak export rate is slightly more than the regular import rate to compensate, on flux? These kinds of adjustments to the overall picture are small, though, whereas the CoP idea was giving an impression of a very large adjustment. 

 

I do treat the grid as interseasonal storage, but it doesn't really have any of it, so doing this doesn't contribute to, say, burning less gas in winter in the same way real interseasonal storage would.

 

If you need cooling, absolutely use it for cooling, though ^^.