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thepilot avatar image
thepilot asked

Quattro with Fronius G99 or G98?

If I'm planning to install a Quattro 48/8000 and use a Fronius inverter (3.6kw) will I need to use G99 or G98 cert? I assume that the Quattro and the fronius will be connected in parallel to the grid so does that mean that the highest rating (Quattro) would need to be approved even if I'm not feeding back to the Grid? Under the G98 reg for the Fronius @ 3.6Kw its just a notification but the Quattro if considered connected woud need a G99 Type A as its rated at 6.5Kw?


Any ideas on how to have this setup under G98?

MultiPlus Quattro Inverter Charger
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4 Answers
wkirby avatar image
wkirby answered ·

If you configure the Quattro to not feed in then only the PV inverter will be able to feed in and remain inside G98.
If there is no additional DC coupled PV or any AC coupled PV on the output side of the Quattro then by default it will be unable to feed in.

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fatbloke avatar image fatbloke commented ·
My, possibly incorrect understanding, is if the device can *potentially* feed in, then it needs Approval. I'm not convinced programming with zero feed-in does it.
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sharpener avatar image sharpener fatbloke commented ·

Exactly what Western Power Distribution told me. Even with my Multi II 5k set for zero feed-in, they also insisted it is limited to 3.7 kW inverter power and that I submit a G99 application on Form A1-2.

Consequently an 8k Quattro even if type approved may not be able to be fully utilised.

WPD do not want there to be any possibility the output can exceed their capacity to accept it, even transiently, because they are worried about exceeding 253 V on their distribution network. They do not accept that the effect is just the same as a sudden 32A decrease in the current I take e.g. me turning off the cooker or my RCD tripping.


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thepilot avatar image
thepilot answered ·

Thanks Kirby,

I'm strguggling to understand the G99/G98 requirements. I dont want to feed into the grid, purely self consumption, but if I connect the Quattro to the AC in and connect a battery that is charged via an MPPT would I require to declare this device on a G99 connection? My assumption was to place a Fronius 3.6kw inverter in place before the Quattro so as to limit the power available to the grid on a G98 connection but I'm lost now!

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fatbloke avatar image
fatbloke answered ·

I'd like to install a 8kVA Quattro, but I can't seem to find any docs which stipulate it is actually "approved" in the UK. I can find a G99 Test Cert, but is that the same as actually being Approved in the UK?

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sharpener avatar image
sharpener answered ·

WPD granted my G99 application when supported by the G99 Test Cert I sent. There is an authoritative list somewhere on the ENA website. But see above regarding whether they will in practice let you have the Quattro turned up to full output.

@thepilot you might be better off having the Fronius on AC Out, then you can argue in addition that its output will have to go through the Quattro which can limit it. Also it will then keep going in a power cut.

I think it is all rather arbitrary, it depends on who the DNO is, who you get hold of and what view they take of the robustness of the network in the vicinity of the proposed installation.

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