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DNO export limit problems.

 
Energy Storage
Last Post by Old_Scientist 9 months ago
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 AdamK
(@adamk)
Reputable Member Member
Joined: 1 year ago
Posts: 216
Topic starter 26/09/2025 4:37 pm   [#2482]

ive had some bad news from the DNO (National Grid). theyve told my potential Tesla PW3 installer that i can only export to 5kw.

 

i already have an existing 3.68kw inverter thats connected to a 4kw array on a FIT.

 

what can i do?



   
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 AgentGeorge
(@agentgeorge)
Estimable Member Member
Joined: 1 year ago
Posts: 172
26/09/2025 5:55 pm  

Ask DNO if its a load balancing on your phase of the supply, and will they allow an Increase at some time in future



   
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 Old_Scientist
(@old_scientist)
Honorable Member Member
Joined: 2 years ago
Posts: 412
27/09/2025 1:21 pm  

How big is your proposed solar array?

I have 7.2kWp array and a 5kW export limit, and it's not overly limiting with a bit of careful battery management.

Assuming peak solar performance, if you force export the battery overnight to start the day near empty, and export 5kW all day with space in the battery to store any excess solar generation that you cannot export or use, it should be possible to manage the 5kW export limit. Plus you can further manage buy scheduling any heavy usage during the solar peak hours to use some of the generation.

Really depends what your solar generation is and how much storage you have.


This post was modified 9 months ago by Old_Scientist

Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW)
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.


   
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 AdamK
(@adamk)
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Joined: 1 year ago
Posts: 216
Topic starter 27/09/2025 10:41 pm  

Might not be to bad as I think it’s just the export limit not installed inverter limit. I’ve got a 4kwp array on another 3.68kw inverter attached to a FIT that I wasn’t planning to mess with. So as I don’t plan to force discharge the pw3 I should be ok.



   
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 Old_Scientist
(@old_scientist)
Honorable Member Member
Joined: 2 years ago
Posts: 412
27/09/2025 11:13 pm  

So you're planning to add a PW3 to the existing setup (4kWp)? In that case the 5kW export limit won't affect you as you shouldn't be generating more than 4kW. Are you planning on adding any more solar in the future?

It will likely be more efficient if you can move the existing array onto the Tesla inverter, being DC coupled. You'll need to ask your installer about any potential; FiT related issues.


Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW)
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.


   
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