Phantom Energy Usage by Solar

williamcroome

Hello. 
I've moved into a new house that has PV system (solar panels with inverter and generator).
Recently I noticed on usage that during the day (when we aren't around) there are hourly periods where 1-2kW are being used. 
I understand that all devices are using a small amount but I would expect those to be fairly consistent over the day, bar the fridge. 
Returning home early I started turning off switches and found to my surprise when I switched off the fuse to the PV system the usage disappeared. So it appear that in "running" the PV it is using some energy. And I don't know but these might be aligned with "sunny" periods.
Of course some usage is to be expected but upto 2kW over a whole hour? 
That would mean it is potentially using more energy than to generate.

Is it possible something is setup incorrectly or is this to be expected. I don't remember this from my old house which also had solar panels. 

TIA

debitcardmayhem

How did you notice this? is it possible that this is export?. Do you have battery(ies)?

williamcroome

Hi, I don't have batteries. 
I just noticed from my usage that during the day (when no one is home) there are periods of time where over 1KW/h is being used. 
The overall usage ties up with meter readings so I don't doubt the usage. 
When I've been in and I've seen the usage "spike" the thing that makes the difference is turning off the fuse to the PV system.

From my rudimentary knowledge of PV I shouldn't see export or generation on my electricity usage.
Only that if running things when energy is generated it will use this first and also some is being exported (metered separately). 

Qyburn

What sort of meter do you have? To me it almost sounds as if the meter is incorrectly registering export as consumption.

Ectophile

There are some electronic non-smart meters that add up all electricity that goes through them, regardless of which direction it goes.  Is it possible you have one of those?

Most meters simply stop if they see electricity flowing the "wrong" way.

williamcroome

I did think it might be the meter but then on a sunny day (and I appreciated we have had only a few of these) wouldn't I expect to then see a usage thoughout the day. This happens much more sporadically.  Maybe just an hour here or there. I guess I need to keep an eye on it. Maybe get an MCS engineer to review and make sure the setup is correct.

QrizB

If your solar power system doesn't have a battery, it won't have any way to "use" more than a watt or two from the mains. If it did use 2kW for an appreciable period of time, it would probably burst into flames.

williamcroome said:

I've moved into a new house that has PV system (solar panels with inverter and generator).

New as in new-build, or new as in new-to-you?

williamcroome said:

Recently I noticed on usage that during the day (when we aren't around) there are hourly periods where 1-2kW are being used.

Where have you noticed this - on your smart meter in-home display?

Does your house have an immersion heater in the hot water tank? On a timer, and/or with a solar diverter?

williamcroome

New to me. House built in 1950s. Solar installed around 2018. 
I notice this on the HID but the display readings match the smart readings. 
Yes - it has immersion but it is turned off from electric and heats via oil twice a day at set times.

tim_p

Have you tried turning the breaker off that feeds the solar inverter and seeing if the usage spikes stop?  At this time of year the solar generation is so poor that any loss of generation will be minimal. 

williamcroome

Unfortunately the same circuit appear to have the shower pump on it so not possible to turn off permanently. 

tim_p

Surely it doesn’t need to permanently, just turn it off between showers and monitor the usage. Quite why it’s on a circuit with the shower is beyond me I’m afraid, surely can’t satisfy MCS regs.