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Running from backup generaor in powercut?

Pipcart · 2026-01-07T09:54:56Z

Does anyone have experience of running an ASHP from a backup generator, even with only with minimum output to prevent freezing during a power cut? Our system has antifreeze valves, but I really dont want these to be triggered. If you are able to run from an emergency generator, then a brief description of your setup would be much appreciated. We need to install a backup generator anyway, to keep essentials (e.g. sewage system) running during a power cut and we'll ask an electrician to provide the necessary connections - the ASHP has its own distribution board.

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Mars

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09/01/2026 9:34 am

Right on topic, Storm Goretti has done its thing and we’ve been without power since last night… looks like we’ll be lucky to have power restored by 9pm tonight according to text messages from the DNO.

The fires are on and downstairs is heating up.

I do find it odd how ‘fragile’ the electricity infrastructure is in the UK. We ended up having about 25cm of snow last night, and no overly strong winds, so I’m really surprised that huge areas around us are without power.

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Transparent

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09/01/2026 12:18 pm

Here's the Power Cut map from Cornwall at 23:00 last night

The best strategy for adding a (diesel) generator is to connect it to a dedicated input on a hybrid storage inverter.

That allows it to run in its 'sweet spot' for efficiency whilst re-charging a battery.
And the inverter will switch it off when the stored energy reaches a threshold which you configure.

Here's the notes from the Sunsynk inverter, describing how the relay contacts can be wired to
start and stop the generator automatically.

Posted by: @editor

↑

I do find it odd how ‘fragile’ the electricity infrastructure is in the UK.

The technical term for this is "low resilience".

Commercial companies are busy adding Battery Electricity Storage Systems (BESS) all over GB, claiming that this will increase resilience.
In most cases, that's bunkum. If the power-lines are down there's still no supply to consumers.

This post was modified 12 hours ago by Transparent

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Mars

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09/01/2026 1:50 pm

@transparent, super interesting.

I had a long chat with the ‘reconnaissance’ team from Scottish Power a short while ago, and what a nightmare trying to track down the issue. The grid, around us anyway, is not fully self diagnostic so it’s a lot of legwork and visual inspections. Massive faff.

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Transparent

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09/01/2026 2:40 pm

I haven't previously met the concept of the local grid being fully self-diagnostic.

The DNO Engineers have a device they can attach to the wires which bounces back a signal from where a wire is broken (open circuit).
That allows them to travel to within one pole of the fault.

Here in the West Country we get notification of when they expect power to be restored in an affected area:

Currently we have NGED engineers working in Cornwall from elsewhere in the UK.

That can cause confusion when they don't understand our place names:

This might be a good moment to inform the wife that 2026 is going to be the year when you assemble and install your own off-grid storage battery.

If that news is met with stone cold silence,
defrost her before trying again.

This post was modified 10 hours ago by Transparent

This post was modified 9 hours ago by Transparent

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Mars

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09/01/2026 2:53 pm

Our DNO has updated our restore time to 21:00, after the initial update that said we’d be back by 10:00.

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Toodles

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09/01/2026 4:42 pm

@editor It is just as well that you possess some fossil fuel burning devices! But I do feel for you both nevertheless. We have been lucky in the SE of England with just heavy rain for a few hours and it was a bit blustery overnight. I hope the supply is resumed earlier than they have predicted though. Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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Majordennisbloodnok

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09/01/2026 5:56 pm

Posted by: @editor

↑

Our DNO has updated our restore time to 21:00, after the initial update that said we’d be back by 10:00.

It seems the Microsoft minute has been usurped by the Scottish Power hour.

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

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Toodles

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09/01/2026 6:54 pm

@majordennisbloodnok Back in the 80’ or 90’ we had a team of electricians from the local electricity board working at the college; they explained to me that they worked to a metric hour based on 100 minutes to each hour 😳 Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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