Whats chewing my power? Diagnosis help!

Rorschach

Paid $250 for this custom title
Bit of a random one, but a wide spread of experience here so thought I'd ask.
Late last year, I had a solar system put in with a smart power meter and a wifi inverter. This means I can have a look on my phone and work out when I'm using power, how much I'm sending to the grid etc. The bills are getting smaller, which I'm happy about, particularly as the wife and kids are at home during the day, so using the 'free' power rather than drawing off the grid.
Since I started looking at the data, something has been chewing my power up for a few hours between around say 3am and 5am. This isn't every day, or at the same time every day. My first thoughts were that it was the water heater coming on when the temperature dropped below a certain level, so I put a timer switch on there but it doesn't seem to be that.
I don't have anything that should be sucking power, other than the standard household appliances that would be on all night like the fridge. Everything else is either off or on standby.
Anyone any ideas, other than my neighbours stealing my power for a hydroponic set-up?
 

Daniel Hale

She fid, he fid, I fidn't
3am is a common time for updates for computer based things ,like PC's/laptops/phones -could it be you're devices running updates then installing when windows/apple push them out
even though your fridge is on -being unopened for a while it will still lose temperature -has to kick in some time, ditto the freezer
 

Mattyp

Likes Dirt
Most fridges have Defrost cycles in them, sometimes a heating element to warm things up to melt ice build up, then they go into boost mode to make everything cold again.
 

Tubbsy

will do custom titles for cash
Staff member
You could get one of those power-tracking plugs, I think they're only $30 or so and rotate it around a few of the more likely candidates until you find out what it is. Fridge does sound like a likely contender.
 

Rorschach

Paid $250 for this custom title
How much power are we talking?
about 2.5kW for a couple of hours most nights

3am is a common time for updates for computer based things ,like PC's/laptops/phones -could it be you're devices running updates then installing when windows/apple push them out
My laptop only does updates every now and again, I only pick it up once a week so I don't think its that, and it wouldn't be using this much power

even though your fridge is on -being unopened for a while it will still lose temperature -has to kick in some time, ditto the freezer
Most fridges have Defrost cycles in them, sometimes a heating element to warm things up to melt ice build up, then they go into boost mode to make everything cold again.
There might be something in that, but we don't hear any noise from the fridge/freezer other than the usual compressor cycle
 

Rorschach

Paid $250 for this custom title
You could get one of those power-tracking plugs, I think they're only $30 or so and rotate it around a few of the more likely candidates until you find out what it is. Fridge does sound like a likely contender.
Might give that a bash and plug it into the fridge and see
 

Rorschach

Paid $250 for this custom title
Is that 2.5kW above background readings? If so fridge or hot water are the only likely candidates to draw that much juice, unless you or the wife are sleep-activating washing machines or tumble driers.
Well above, background at night is less than 0.1kW, when whatever is draining power kicks in, it does so at ~2.8kW. sometime run a dishwasher at night, but not this week as the wife has been home.

Or someone is getting up and making midnight snacks in the oven?
My nose is well calibrated, that'd get me up
 

fatboyonabike

Wheel size expert
there is really only a very small number of appliances that would pull that much current..even a dishwasher would be unlikely to pull that much for so long
 

Rorschach

Paid $250 for this custom title
there is really only a very small number of appliances that would pull that much current..even a dishwasher would be unlikely to pull that much for so long
Hence my thoughts on it being the hot water immersion heater running for a few hours before the solar assist kicks in.
Unless I've got a dodgy timer switch?
 

Mattyp

Likes Dirt
Hence my thoughts on it being the hot water immersion heater running for a few hours before the solar assist kicks in.
Unless I've got a dodgy timer switch?
Those solar assist things on your roof also have a low temperature switch to stop the unit freezing and bursting all the pipes. If it's a cold night 0-4 degrees (or whatever it's set to) the pump will run and send hot water up to the roof to stop it freezing. Sending cold water back into the tank..... You get the idea..
 

Isildur

The Real Pedant
If you hadn't mentioned a timer switch on your hot water system, I'd be leaning towards a "controlled load" electric hot water system. It's what we've got in our house and it kicks in at 12am then runs for 30 minute cycles through to between 2am 3am depending on the amount of hot water we've used.

As it's a Controlled Load circuit operated by the network operator (Aus Grid) in our case, the Sungrow system doesn't actually pick it up, but the total figures from our retailer Discover show it. Have yet to have any word on being able to get visibility of that through the Solar system, but as they're 2 separate circuits it may not be possible. Still in discussions with the solar installers.
 
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