Re: energy in UK

On 2025-04-18 06:44, wmartin wrote:

On 4/17/25 16:57, KevinJ93 wrote:

On 4/17/25 1:50 PM, Carlos E.R. wrote:

On 2025-04-17 21:05, KevinJ93 wrote:

On 4/17/25 2:28 AM, Don Y wrote:

On 4/16/2025 6:55 PM, KevinJ93 wrote:

On 4/16/25 3:49 PM, Don Y wrote:
 > On 4/16/2025 3:11 AM, Martin Brown wrote:
<...>
 > Here, the issue is the high PEAK demands that the ACbrrs place on
 > individual
 > subscribers.  We could probably get by on a 3-5KW plant -- but, only if
 > we could store and deliver for large loads (I think the ACbrr is ~14KW).
>
That's a very large residential A/C. Our 4-Ton unit (48kBTU/Hr) takes about 5kW and suffices a 2,900 sq ft house in northern California. (Don't you like all these antiquated units!)

>
That's the startup load.  An inverter for a (pure) solar solution would
have to tolerate that for some large fraction of a second/seconds. I.e.,
you would NEED to be grid-tied in order to support such large loads,
even temporarily.
>

>
14kW startup is about 60A LRA (locked Rotor Amperage). A single Tesla Powerwall 3 battery is rated for 185A LRA and it is very common to have two or more Powerwalls in a system which increases the available short term power. Our A/C has a 104A LRA spec.

>
What would happen if the inverter on the battery pack doesn't have that peak capacity?

>
The inverter would trip and power would be cutoff until reset.
>

I mean, an inverter might simply limit the maximum peak current without destroying itself, keeping itself all the time within safe limits. Would the motor still start, albeit slowly? Or would it stall and overheat? Perhaps motors could be designed co cope. I know my AC unit has an inverter inside to control the motor, so does my fridge.
>
...

>
>
>

The inverter can be smart enough to start up in "speed ramp" mode. I had the tripping issue on my 3hp lathe motor in high speed gear, until I programmed the inverter to ramp up to speed over several seconds. It's all about inertia in this case, maybe not so simple with a compressor load attached.

I know that the classical motor in a fridge has a device, I don't know its name, that thermally triggers if the motor demands an unusual high current for some seconds, like when starting under load. It then keeps the motor off for a long time (minutes?), while the compressed gas leaks into the circuit, the pressure drops, and then the motor tries again.
Surely a modern fridge or AC unit with inverter knows how to cope with the situation.
--
Cheers, Carlos.