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Am I permitted to fit a second solar panel+inverter?

Solar Photovoltaic (PV)

Last Post by Transparent 3 years ago

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ronin92

(@ronin92)

Estimable Member Member

Joined: 4 years ago

Posts: 64

Topic starter 31/03/2023 12:19 pm

I have an existing 4kWp solar panel+inverter under FiT on my home currently. That's behind its own generation meter and export is on 50% deemed.

I want to install battery storage and will be charged 20% VAT on it. Can I just put in an AC-coupled second inverter+battery with 1-2 panels (I have space for that) to avoid VAT? Will the DNO permit that? It will be grid-side of the existing generation meter to stay-FiT compliant.

As I see it, my smart meter is not being used to measure export under FiT so anything exported from the 2nd installation shouldn't result in unwarranted income either. In the worst case, I suppose could opt out of FiT export payments and go to another export tariff.

As to why I'm on deemed when I have a smart meter, I told my FiT processor when it was installed but they left it be.

P.S. I am aware that there's been a call for evidence to remove VAT from batteries and such like but when VAT policy may change as a result is unknown.

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Transparent

(@transparent)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 2558

04/04/2023 10:43 am

Posted by: @ronin92

↑

Can I just put in an AC-coupled second inverter+battery with 1-2 panels (I have space for that) to avoid VAT? Will the DNO permit that? It will be grid-side of the existing generation meter to stay-FiT compliant.

Do you feel up to doodling your intended system diagram and posting it here please @ronin92 ?

You can literally do a pencil sketch on the back of an envelope and take a smartphone photo!
I have the facility to redraw that with relevant graphic icons if we need it to aid our discussion.

You will certainly need consent from your DNO.
Which region are you in?

In adding another string-inverter and a storage battery, your house will effectively have three devices with possible export capability to the grid:

existing solar inverter
new PV inverter (which will export if the battery is full)
the storage battery itself (depending on the mechanism it uses to create the 50Hz sine-wave output)

The DNO would evaluate those three devices, then look at the method used for export-limitation, and issue a G99 approval letter if they're happy.

It costs nothing to make an application for G99.
This can also be done by the householder rather than a professional installer.
So if your strategy is rejected, you can always amend what you've proposed and then resubmit.

The majority of G99 applications are handled using a Fast-Track process.

The Electrical Networks Association issues the following guidance for you to check if G99 Fast-track applies to your site

If that seems like a mess of terminology, then please say so and I'll expand it until it makes sense!

I've deliberately avoided any comment of costs, viability, FIT-payments etc. at this stage.

This post was modified 3 years ago 2 times by Transparent

Save energy... recycle electrons!

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ronin92

(@ronin92)

Estimable Member Member

Joined: 4 years ago

Posts: 64

Topic starter 07/04/2023 1:58 pm

@transparent Thanks.

I'm envisaging a system something like that below. I want to add batteries to a MSC-approved solar installation registered on FiT scheme. This installation has a nominal 4 kWp output but I've never seen >2.6 kW because of its E-W configuration.

The only reason my proposed new installation has panel(s) included is to avoid VAT. I'm wondering if it looks like the kind of thing that gets approved.

I've been speaking to prospective installers.

One prefers me to replace the existing inverter with a hybrid inverter+battery as it saves getting DNO approval. I am reluctant to do that as battery round trip losses from panels and grid will be deducted from my FiT generation. Another tells me their lawyers say VAT is not applicable for batteries if you already have a solar installation which is news to me!

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Transparent

(@transparent)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 2558

08/04/2023 11:10 am

Posted by: @ronin92

↑

One prefers me to replace the existing inverter with a hybrid inverter+battery as it saves getting DNO approval.

That's because you and he are only considering that new inverter also having grid export capability.

Have a look at this posting from me yesterday.
It has diagrams showing the two main approaches to inverters coupled to batteries.
The description is still valid, even though that topic was started by a member who does not have PV solar panels.

Save energy... recycle electrons!

👍

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