SMA inverter drawing current overnight.

[Saveandgenerate]

I have a SMA 3800 inverter with 3.96 kW Romag panels that is drawing around 20-40W in the evenings. The inverter is shut down and it's still drawing. When I isolate the system the draw stops. There is a cable run of about 40m between distribution box and inverter then 10 meter run up to the roof. There are isolators at both the inverter and at the distribution box.

Over a year we're looking at drawing 150 kWh! We're on economy severn but that's not the point. Aside from turning it off every night any suggestions?

 

[pmac10]

you say the inverter is shut down, could this shut down drop out a contactor which supplies the inverter?

 

[Saveandgenerate]

When I say shut down, it's the automatic sleep mode built in to the inverter program.
Are you saying that if the auto shut down drops out a contractor that should shut down the inverter supply this could leave it drawing the current.
I'll be honest I'm treading water technically here. I'd be interested in was if anyone else was monitoring a system and had noticed it as it's a standard system set-up in the last 6 months.

 

[pmac10]

no mate, i'm thinking this may be normal, if you think of your laptop, when you put it to sleep it will still draw current as opposed to shutting it down. im not familiar with this inverter but if i was presented with this problem i would maybe use the drive enable signal to input a timer which would control the supply to the inverter,with every enable signal resetting the timer, as i said, i'm unfamiliar with the inverter or indeed your application, so just an idea.

 

[TedM]

The SMA 3800 should be drawing virtually zero in sleep mode "< 0.1 W" - see the Technical Data tab at SUNNY BOY 3300 / 3800. SMA Solar Technology AG

You need to double-check that the programmable parameters in the inverter are all set correctly and that the inverter really is going into sleep mode when the input voltage drops.

 

[edexlab]

I've read about this on Iet forum the customer was concerned about same issue they were monitoring the system using a clamp on energy monitor from a supply company , some of the contributors to this post were saying that these monitors were giving false readings ,as these devices were'nt calibrated as accurately as say our test instruments , and also that they're not designed for this application hence strange readings, I'll have to have another look as this was a while ago

 

[Saveandgenerate]

I'd love to hear what the outcome of this forum was, that would be great. Yes, I am using a current cost monitor with a CT clamp but it reads zero when you turn it on and is sensitive enough to pick the draw of a 5W light bulb through the domestic circuit. Whilst I'd not want to pay FIT payment based on monitor read out, it can certainly register a current and I don't doubt it in this case. In desperation I even checked that I wasn't generating overnight!! I wasn't.....

 

[edexlab]

too much to include here i would suggest you have a look and see what you think

 

[Saveandgenerate]

checked out the thread. Now my head hurts! If the current cost meter does not take voltage into consideration it looks like it could be a false read due to a super low power factor. The only way to tell is to get a wattmeter. Any suggestions on a good but inexpensive piece of kit I can get? (the call of the deep pocketed short armed man!)

 

[JEM]

checked out the thread. Now my head hurts! If the current cost meter does not take voltage into consideration it looks like it could be a false read due to a super low power factor. The only way to tell is to get a wattmeter. Any suggestions on a good but inexpensive piece of kit I can get? (the call of the deep pocketed short armed man!)

I have a similar problem with a Kaco Powador apparently using 100w when switched to night mode; however my supply meter is not recording any useage (all other circuits turned off) so I'm assuming a false reading on the clip-on power meter but would like to know the technical reason for the false reading.