question

jeanmarie avatar image
jeanmarie asked

Grid consumption with hairdryer despite fully functional ESS

Hi community,

I would like your help to understand why and mostly also how to avoid such a behavior

Installation is

Monofasic ESS installation with

- 84kWh of LFP battery

- 10kVA multiplusII

- fronius 3kW with 3kWc panels bus AC

- and RS450/100 with 5,6kWc panels bus DC

Behavior is

when using a hairdryer I noticed (as I was in front of the local Cerbo console at the time of use) that despite a production of 1500W by the fronius and almost 2000W by the RS450 that with hairdryer on, a consistant and unstable qty of Watt were taken from grid, between 800 and 1500 for a 2000W appliance and during all the time this appliance was running (more than 1 minute), as soon as it stopped, the system came back to a normal behavior with the grid (between -50/+50W to adjust the load).

I also have some high power appliance (Heat pump, EV charger) but never saw such a behavior with the grid consumption.

Could anybody have an idea about what occurs than, as this is fully reproducible, and mostly also give me some hints about how to avoid this (for your info, no, I don't want to change my wife for one without the need of an hairdryer ;) )


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2 Answers
seb71 avatar image
seb71 answered ·

What mode have you set for the battery: Optimized without Battery Life, Keep batteries charged etc. ?

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jeanmarie avatar image jeanmarie commented ·

Mode is set to "optimized without battery life"

This is ESS basic with grid as feed-back

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Rob Duthie avatar image
Rob Duthie answered ·

Hi

Hair dryers have a dc recifier in them and can cause odd readings due to this DC recifier, as they have poor regulation where as other loads like EV charger have better PF control etc.

Regards

Rob D

NZ

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jeanmarie avatar image jeanmarie commented ·
Hi Rob and thank you for sharing this information.


According my opinion Hair dryer should be as simple as a resistor to heat and a basic AC motor for the fan, aren't they ?

Could you complete your answer then:

- is the reading of the consumption by the multiplus so distorted because of the hair dryer that the multiplus is reacting to this false reading by taking from the grid despite the huge gap between the appliance's power (2000W) and the locally available power (12000W)

- or is just the reading of the grid input by the multiplus that is false and baseless because of the bad signal generated by this appliance

I'll try to reproduce it and have a screen dump with the reading of PF/Voltage/Power from a shelly device and the Cerbo console together



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