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Would I be unkind to the Grid?

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Toodles
(@toodles)
Famed Member Contributor
6389 kWhs
Joined: 2 years ago
Posts: 1003
Topic starter  

At present, I have 2 Powerwall 2’s and am thinking about adding a third (Yes, I appreciate ROI is unlikely in my lifetime!) When the battery is charging from the grid, it is drawing some ~42 amps. Adding a third powerwall would take this to ~63. On top of this might be a further 13 amps for my DHW immersion element and in winter - a further ~8-10 amps for the ASHP plus perhaps another ~2 amps for fridge freezer etc. This suggests to me that at a certain time of the night, my drain on the grid could then reach approx 85-90 amps for perhaps 2 to 3 hours!

I do not know the size of main fuse but I do remember my DNO did replace it after the previous one expired 30 years or more ago. (Actually, they were fitting a new meter and changed the fuse at the same time but no way can I see what the current rating is). I think the Powerwall can be configured to charge at various rates but I have not investigated this as yet. I would rather not find out that if my supply has an 80 amp fuse, it would blow under the above mentioned load. However, my point is… Am I being irresponsible in demanding this amount of current on a domestic circuit? I have G99 approved as I have solar panels and a battery which can both export to the grid and at present, I do export up to ~ 50 amps or so. Regards, Toodles.

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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(@judith)
Estimable Member Member
780 kWhs
Joined: 8 months ago
Posts: 62
 

It’s more like it will be unkind to you!

In a damp Welsh holiday cottage in December with -2C outside we put on electric heaters to warm and dry rooms and the electric cooker was on. We blew the main fuse!

it took many hours with no power before the man arrived to reconnect us and we were cold and hungry. 

Since you control your battery charging to match Agile’s lower rates you can also stagger them for a penny or two more to keep below 80% of max, and you need to know what that is. It might be 60A or it might be 100A. Main fuses are not slow-blow so a switch on transient (mainly motors) could take you over the limit.

6kW PV south-facing roof 9.5kWh Givenergy battery. MVHR. Investigating ASHP


   
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Toodles
(@toodles)
Famed Member Contributor
6389 kWhs
Joined: 2 years ago
Posts: 1003
Topic starter  

@judith Oh Judith! I feel for you, during Covid Lockdown, we had SSEN working in the road on a cold winter’s day and they needed to turn off the supply for about 12 hours to carry out repairs to a section of cabling. As a consequence, we had no heating (gas c/h with electronic control and pump), no cooking (gas hob with electronic safety cut off control), no hot food as hob and microwave cookers not useable. My wife has special dietary requirements and no-one would deliver such food to us at home (no buses on our route due to Covid restrictions.) Were we glad when we had power back after dark! Regards, Toodles.

This post was modified 1 month ago by Toodles

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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