AC coupled storage system

[Westie]

We’re 11 years into our 25 yr FiTs contract and I would like to add storage, obviously a DC coupled battery with hybrid inverter retrofit would be nice but that’s going to put the FiTs contract in breech of the T&Cs. So looking for a standalone AC coupled system which, when the FiTs contract ends, I can then hook up to the existing array and be reconfigured as a DC coupled system. I specifically would like to use a system which can take advantage of Octopus Agile, so has anyone found a reliable system which can use the Agile ToU data feed and set charging times based on price thresholds. So far I’ve only found two suppliers, namely Powervault and Fox , who say they can do what I want , has anyone here invested in either of their ‘Works with Octopus’ systems?

Any other suggestions welcome!

[Stinsy]

The squirrel pod is “Agile Aware” too.

However there aren’t many people for whom Agile works. Go is almost always a better choice.

[Thebeeman]

There is a supplier selling Lux Power systems as being 'Octopus Agile' friendly, at least that's what the website and quote says.

[sharpener]

I don't see why keeping the existing AC-coupled PV and putting it on the output side of the hybride inverter would be in breach provided it does not involve changing the existing Total Generation metering arrangement. What aspect is it your FIT company does not like?

[nowty]

With agreement from the FIT provider (easier said than done), the existing inverter could be replaced with a hybrid inverter and if the batteries are capable to be charged from the grid, the generation meter can be changed for a bi-directional one.
https://theecosupermarket.co.uk/product ... ion-meter/

Its in the OFGEM FIT guidance document, page 35, section 4.25.
https://www.ofgem.gov.uk/sites/default/ ... uidnce.pdf


PS - How much PV have you got Westie ?, or average annual generation, for my secret list of Camelot Members Green Generation.
https://camelot-forum.co.uk/phpBB3/view ... f=13&t=922

[Westie]

The squirrel pod is “Agile Aware” too.

However there aren’t many people for whom Agile works. Go is almost always a better choice.

Thanks for that Stinsy , that looks very interesting. Will do some research on Lux for sure. I agree re- the Go tariff but I don't have an EV as I still travel quite a bit and the infrastructure around here is poor.

[Westie]

I don't see why keeping the existing AC-coupled PV and putting it on the output side of the hybride inverter would be in breach provided it does not involve changing the existing Total Generation metering arrangement. What aspect is it your FIT company does not like?

Thanks Sharpener but you've lost me there! Could you elaborate or sketch it out for me? The aspect they wouldn't like is the ToU grid charging, the TGM on the existing system is unidirectional ie only counts export, so if for instance, the DC coupled battery accumulated 5kwh overnight from the grid the import would not be counted, that would tho add 5kwh to the TGM when the battery was discharged. Nice but illegal

[Westie]

With agreement from the FIT provider (easier said than done), the existing inverter could be replaced with a hybrid inverter and if the batteries are capable to be charged from the grid, the generation meter can be changed for a bi-directional one.
https://theecosupermarket.co.uk/product ... ion-meter/

Its in the OFGEM FIT guidance document, page 35, section 4.25.
https://www.ofgem.gov.uk/sites/default/ ... uidnce.pdf


PS - How much PV have you got Westie ?, or average annual generation, for my secret list of Camelot Members Green Generation.
https://camelot-forum.co.uk/phpBB3/view ... f=13&t=922

Thanks Nowty, you knowledge on this stuff is encyclopaedic! I read about bidirectional metering being able to used to allow DC coupled hybrid systems to be allowed under a FiTs contract but never would have found the info you've provided. However even if I achieved legitimately retrofitting a DC coupled hybrid store I can just imagine how many times I'm going to have to explain this to the FiTs provider/meter reader and the actual process of registering the changes to legitimise the system would be challenging - especially as the solar FiTs scheme has ended I suspect. Do know anyone who has succeeded doing this?

[nowty]

However even if I achieved legitimately retrofitting a DC coupled hybrid store I can just imagine how many times I'm going to have to explain this to the FiTs provider/meter reader and the actual process of registering the changes to legitimise the system would be challenging - especially as the solar FiTs scheme has ended I suspect. Do know anyone who has succeeded doing this?

Unfortunately that's probably the case, it really depends whether your FIT provider is on the ball or not and they don't like doing anything other than the minimum for their OFGEM admin fee.

[sharpener]

I don't see why keeping the existing AC-coupled PV and putting it on the output side of the hybride inverter would be in breach provided it does not involve changing the existing Total Generation metering arrangement. What aspect is it your FIT company does not like?

Thanks Sharpener but you've lost me there! Could you elaborate or sketch it out for me? The aspect they wouldn't like is the ToU grid charging, the TGM on the existing system is unidirectional ie only counts export, so if for instance, the DC coupled battery accumulated 5kwh overnight from the grid the import would not be counted, that would tho add 5kwh to the TGM when the battery was discharged. Nice but illegal

I am suggesting you move the connection between the existing Total Generation Meter and your supply/consumer unit to the output side of a hybrid inverter that has separate input and output connection (e.g. a Victron MultiPlus) like this https://www.victronenergy.com/live/ac_coupling:start.

Then (i) you haven't disturbed the connections between your panels, the solar inverter and the TGM and (ii) there is no possibility of power from the batteries flowing through the TGM in the way you describe, so the DNO should approve your G99 application and you do not need to worry about bi-directional meters or even notify your FIT company.

You can also connect additional PV to the battery via a DC-DC MPPT converter and all this remains true. I can't see why this would not be compatible with a ToU tariff either, I have Economy 7 but others e.g. Agile may suit you better.