Power cuts, and PV systems

[pulhamdown]

First of all, apologies.  I seem unable to select a suitable area for this post.  We built a low energy house in the Vale of Strathmore in Scotland four years ago.

Yesterday we had a planned power cut.  I received a letter from Scottish Hydro informing us that the power would be off all day.  No mention of turning off my PV system in the letter, despite the fact that they are also my supplier, and know that I have a PV system.  My question is had I not turned off my PV, would current have flowed back into the grid to the detriment of the linesmen?  Or does the inverter require mains electricity to operate?   Whilst walking the dog, I spoke to a couple of guys who were jointing an underground cable, and asked them whether my PV should be turned off.  They didn't seem very interested, but gradually the penny dropped.  They didn't know either!

Then I got thinking.  If I had a diverter taking the vast majority of my excess generation into my three immersion rods in my thermal store, would I need to turn off the PV in the event of a power cut?  It is purely theoretical, as at the moment I have a 1969 disc meter which goes into reverse when I generate more than I am using.  In a house built 4 years ago.  Installed by Scottish Hydro from the house we demolished!  So planning for the future when I have to get a more up to date ( but not smart ) meter.  I would appreciate info from folk more versed in electricity than I am.

 

Colin

 

[Jeremy Harris]

12 minutes ago, pulhamdown said:

First of all, apologies.  I seem unable to select a suitable area for this post.  We built a low energy house in the Vale of Strathmore in Scotland four years ago.

Yesterday we had a planned power cut.  I received a letter from Scottish Hydro informing us that the power would be off all day.  No mention of turning off my PV system in the letter, despite the fact that they are also my supplier, and know that I have a PV system.  My question is had I not turned off my PV, would current have flowed back into the grid to the detriment of the linesmen?  Or does the inverter require mains electricity to operate?   Whilst walking the dog, I spoke to a couple of guys who were jointing an underground cable, and asked them whether my PV should be turned off.  They didn't seem very interested, but gradually the penny dropped.  They didn't know either!

Then I got thinking.  If I had a diverter taking the vast majority of my excess generation into my three immersion rods in my thermal store, would I need to turn off the PV in the event of a power cut?  It is purely theoretical, as at the moment I have a 1969 disc meter which goes into reverse when I generate more than I am using.  In a house built 4 years ago.  Installed by Scottish Hydro from the house we demolished!  So planning for the future when I have to get a more up to date ( but not smart ) meter.  I would appreciate info from folk more versed in electricity than I am.

 

Colin

 

 

No, the PV inverter has a safety cut off, so as soon as the grid goes down the PV inverter shuts off.  The grid needs to be up, within voltage and frequency limits, and with an impedance that is below the inverter cut-off threshold, for the inverter to switch on the output side.

 

There's no need to turn off a PV system unless it's being worked on, usually.

[pulhamdown]

5 minutes ago, JSHarris said:

 

No, the PV inverter has a safety cut off, so as soon as the grid goes down the PV inverter shuts off.  The grid needs to be up, within voltage and frequency limits, and with an impedance that is below the inverter cut-off threshold, for the inverter to switch on the output side.

 

There's no need to turn off a PV system unless it's being worked on, usually.

Thanks for that.  As always the members of this forum provide us amateurs with great information.

[SteamyTea]

You can get a letter from the DNO asking you to disconnect for a number of reasons.

One is that the installer has not submitted the correct paperwork to them.  It is best not to ignore those sorts of letter.