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Author Topic: Export Limitation when adding a new PV system & batteries  (Read 670 times)
ASB
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« on: August 29, 2020, 07:38:13 PM »

Currently we have a 4kWp west facing system using a Solaredge Inverter limited to the usual export limit. I don't want to alter that system as it could affect FIT payments.
Also, we already use more than 70% of generation, so want to stay on deemed export.

I am looking at the possibility of adding a new 4kWp system to our East facing roof & also an 8kWh battery system at our home.

Before making enquiries with potential suppliers I would like to clarify my understanding of how Export Limitation works.

There is no one else on our road that has a PV system, so we may get permission from the DNO to to have a higher export limit, but we would prefer to use the majority of what we generate anyway.

Does the Export Limiter monitor the total export at the meter tails and would it work by controlling the new system inverter to prevent exporting excess power above an agreed level, if we were not using it all?

For example, if we were allowed a new limit of 5kWh, and the combined systems were producing 7kWh at midday, but we were using 5kWh leaving 2kWh export would the limiter not have any effect?
But if we were only using 1kWh, the limiter would reduce the output of the new system by 1kWh?

Also, how does having the battery system affect the DNO limit and the Export Limiter?

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4kWp, W roof, 30 pitch, Solar Edge Inverter + Optimisers. South Wales Valleys, Installed Aug 2015. Octopus Agile Electric Tariff.
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Iain
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« Reply #1 on: August 29, 2020, 11:38:24 PM »

Hi
Just a thought, why not have a battery unit that accepts the dc input of the new PV. Therefore no need for export limitation.
I know the Powervault will accept AC or DC but not sure if it will accept both. There might be systems out there that will.

Iain
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Ted
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« Reply #2 on: August 30, 2020, 10:53:44 AM »

If all grid connected then your system, including both the existing 4kW and any new addition, would need to comply with G98/99 and G100.

You can find all the information on G100 - Technical Guidance for Customer Export Limiting Schemes, including the document itself, here:

https://www.energynetworks.org/electricity/engineering/distributed-generation/engineering-recommendation-g100.html

And how the Fast Track application process works is described here:

https://www.energynetworks.org/electricity/engineering/distributed-generation/fast-track-storage.html


You should talk to your DNO in the first instance to understand the limitations for your specific location, then you can talk to prospective suppliers with the right info at hand for the system to be designed to meet both your and the DNOs requirements.

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« Reply #3 on: August 30, 2020, 11:13:12 AM »

We had a similar idea/situ. Might be of some help. Our solution was to stay within deemed export limits and install the extra solar pv output directly to batteries. It worked a treat. You may find a different outcome as you are pre batteries and I added to an existing set of equipment.
https://www.navitron.org.uk/forum/index.php/topic,31836.0.html
« Last Edit: August 30, 2020, 11:45:12 AM by pantsmachine » Logged

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