@transparent wow amazing information. So that means I could actually use a SPF300 without a g98 permit for my 12kwh storage batteries ( Octopus go to charge batteries off peak/cheap  0:30-4:30am, so I can use the stored energy for the rest of the day if that makes sense? )  Ps: no solar and export involved. Thank you

Yes @astranger you're ok to use the Growatt SPF5000ES with no solar, and it can't export.
There's also an SPF6000ES announced, but it's only had a limited pre-production run to enable a few to be tested in the field.

There's no such thing as a Growatt SPF-series inverter with a G98 certificate, precisely because it cannot possibly have the 240v AC output connected back to the grid.
It's internal 50Hz oscillator would be fighting against the combined might of all the power-generation from the National Grid.
I think we know who'll win that battle!

Sunsynk inverters have both grid-tied and off-grid outputs. They can also work off-grid because their zero-export technology is ENA-approved in UK.
I've spoken with a senior design engineer in South Africa, and they seem to have thought through all the options carefully.
However I haven't tested any of their inverters yet.

Voltacon have a range of Conversol inverters, similar to the Growatt SPF range.
I'll be talking with them shortly.

It's possible that the Phocos inverters can also operate off-grid in the UK. But they need a bit more research.
The specifications I've read thus far haven't covered all the issues which need addressing.

Yes, there's a rich feast of information available here on this forum, and free of charge.

The 'deal' is that you must tell others about the technologies which we're discussing on the Renewable Heating Hub. 🙂 
We need to ensure that as many people as possible are aware of strategies to combat the energy crisis and Climate Change.

@transparent Thank you for your answer and I really appreciate your help. I was considering buying a growatt but they seem to be notoriously high idle power consumers from what I read, same for Sunsynk. What do you think of Victrons? I know they are a lot more expensive however I'm happy to pay a premium for extra efficiency. Cheers

Victron operate in the renewable-energy theatre in the same way as Apple do in digital electronics.

It's well designed and expensive.
Once you go down that route, you're basically sticking with Victron for everything.

In contrast, other companies are offering devices which allow you to mix & match as you choose.
I'm currently running a multi-battery off-grid system with BMS units from two rival companies.
Neither of them is happy with that arrangement... each suggesting that it's outside their use-conditions.

But I have yet to be supplied with a scientifically-valid argument to substantiate their position.
Neither BMS can possibly 'know' about the other!

For those eager to explore the possibilities for DIY battery storage installations,
... this afternoon I conducted a test which produced a dead short-circuit across the output of a 14kWh battery.

It's a 16 x 280Ah LiFePO4 arrangement with a Jiabaida BMS

I hadn't scheduled the test for today.
It was a by-product of installing a new busbar combiner/splitter board. 😮 

The volume was acceptably loud, but not alarmingly so.

Battery and I both survived intact.

Advice needed:

I can source a Sunsynk hybrid inverter and 10kw battery system. 

My question is, is it then straightforward enough to then get it installed by a mcs electrician if I get the appropriate DNO certification etc?

I already have an inverter linked to solar but it's not hybrid so assume it's swapped out to accommodate the battery installation?

Just as personal update. So far this month my total power bought for everything is 13kw off peak - so just over £1 so far. Not too shabby for all my heating and power use needs. 

Posted by: @bretix

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... is it then straightforward enough to then get it installed by a mcs electrician if I get the appropriate DNO certification etc?

Can you elaborate on why you think an electrician with MCS credentials is required?

The reason that consumers engage an MCS approved contractor for solar panels grid-tied via an inverter, is that the certificate number is required by your Energy Supplier. That is used to register you for the Smart Export Guarantee, and pay you the few pence being offered.

Presumably you already have income from the electricity sent back to the grid.
You don't need to re-register.
Energy Suppliers don't monitor whether the kWh being exported is commensurate with the values stated on the original MCS certificate.

There are no mechanisms to check if anything has changed since that initial installation.
In fact, the entire MCS system appears to operate devoid of any inspections...
... a situation which wouldn't be deemed acceptable for electricians.

You can employ anyone you want to connect new inverters and storage batteries.

The only rule which applies is that all mains connections (above 75v) must be implemented by a qualified electrician.
They will notify their certifying organisation (such as NICEIC) and the Local Planning Authority in order to comply with Part P of the Building Regulations.

You will receive a Part-P certificate and a copy of the electrical test-sheet completed by  that electician.
These form part of the documentation which will be requested by a solicitor if you sell the house at some future date.
So keep them safe somewhere!

@transparent that's really useful thank you that'll solve my dilemma. I've been trying to sort my seg out with Scottish Power for well over a year now and wasn't sure how this worked.

Apparently my export mpan has been set up but still waiting for the next part of the process waiting for an email to set up my bank account etc....it's been a long frustrating process to say the least but the silver lining is that the payments have gone from 5.5p to 15p /kw

@transparent 

I'm "listening" eagerly to this thread too!  We have old 4kWp FIT PV with an MCS form, and I now have dno approval for an additional, independent, Sunsynk hybrid inverter.  My understanding is then that the bare minimum "official" thing I need to do is get a sparky to connect up a new circuit to our consumer unit.

While we get FIT (17p thank you!), we opted out of deemed export years ago when we were on V2G.  We're now with Octopus Go (due to elec car and V2H), and I guess I should crack on and get Octopus SEG.  We're an all elec house now, and a few more PV panels will get us to net zero kWh in/out.  

Posted by: @robl

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My understanding is then that the bare minimum "official" thing I need to do is get a sparky to connect up a new circuit to our consumer unit.

Yes. 🙂 

Whilst I don't mind 'upsetting' MCS, there are good reasons why I always advocate staying the right side of the rules which apply to DNOs and qualified sparkys.

As you will be adding a second 'device' capable of export to the grid, you have rightly obtained the G99 approval from your DNO.
For the sake of others who will read this in future, that G99 application is required even if the new SunSynk inverter is to use their inbuilt zero-export technique.

Posted by: @robl

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My understanding is then that the bare minimum "official" thing I need to do is get a sparky to connect up a new circuit to our consumer unit.

Posted by: @transparent

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As you will be adding a second 'device' capable of export to the grid, you have rightly obtained the G99 approval from your DNO. So not just any sparky will do.

My application to UK Power Networks for a 5kW hybrid inverter needs to have commissioning data (and circuit diagrams)G99 A1.1 Declaration - to be completed by Generator or Generator’s Appointed Technical Representative