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quoyshakes avatar image
quoyshakes asked

UK G100 workaround

Looking to get some advice on the operation of the Multiplus 2.

As MP2 does not have a G100 Cert. I have been looking at way to remove the need.

We have a small farm in the UK with a single phase 230v supply so do not need a massive system but more than your average family home.

Our DNO has advised an initial export limit of 3.68Kw on enquiry.

I should be able to install a MP2 (firmware 510) as G98 with the 16A limit.

Would it be possible to operate 2 or 3 MP2 5k in parallel. But have only one unit connect to the incoming supply, providing charging to a battery system and passthrough. the other units would operated as off grid, using a battery (system would also have DC coupled PV).

As operating in parallel all AC out would be combined to provide a single phase output.


multiplus in parallel
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matt1309 avatar image matt1309 commented ·

Is MP2 not G100 compliant?

Microsoft Word - G100 declaration Multi vii (midsummerwholesale.co.uk)

Looks old but maybe worth chancing it and asking your DNO before you design a more comlpex system.


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quoyshakes avatar image quoyshakes matt1309 commented ·

Sadly the requirements for G100 have been updated since that Declaration.

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matt1309 avatar image matt1309 quoyshakes commented ·

I'd still chance it if I were you and ask them... Worse case scenario they confirm you're right and say no you need another solution. Best case they pass it and you have more basic easier to install (and cheaper) setup.



My other guess (I've never done this so not 100% sure if it's possible but agian DNO will be able to tell you either way). But could you not get the unit tested ie a one off installation.

I believe this is how installations are complete when manufacturers have inverters that are not type tested. ie the unit needs to be tested on installation rather than relying on manufacturer specs


You might have to pay DNO/electrician to come complete the test.

ie can you comply with G100 even if G100 type testing hasnt been complete assuming the G100 requirements are met even if not type tested (ie the specific installation is tested to comply).

I've not read up on them recently but when i last looked the G100 requirements boiled down to how fast the system reacted when limiting export was required. I imagine the multiplus complies with this easily but it might just not have the certificate/type testing for it.

Imagine it'll cost you more for DNO/electrician but might work out cheaper than buying/designing a more obscure complex system.


Before spending money definitely give your DNO a ring see if they have suggestions. I've had some scarily good luck doing that in the past


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Craig Chamberlain avatar image Craig Chamberlain matt1309 commented ·
Good advice I'd say - and I strongly suggest phoning the DNO and talking to them rather than communicating via email. I found email "ping pong" with my DNO very slow and prone to misunderstandings but a 5-10 minute phone call could achieve the same as a month worth of email back and forth!
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quoyshakes avatar image quoyshakes Craig Chamberlain commented ·

I agree that the perfect solution is to work with the DNO, but one aim is to keep this totally DIY (I have qualified electricians and solar installers in the family) and costs down.


The other aim was to allow future trials of G100 set-ups to test how they worked, but without exceeding the 3.68Kw DNO export limit.

basic-concept-layout.jpg I have added a basic diagram.

Simplicity is the key here and replies on the MP2 48/5000 having a 16A export limit in the newest firmware so falls into G98.

In the future i can add the grid meter etc, to achieve G100 operation with all 3 units grid ties.

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slartybart answered ·

I was recently allowed to install the larger 8000vA model under a g99 fast track. I was told my export limit is 3.68kW and lo and behold the grid code in the new software 510 states it’s now automatically limited to 16amps and G98 compliant. I’ve sent off screen shots of that and await a response to my commissioning letter. As far as running three units in parallel, I don’t think that would work as the three work together….. so one connection serves all…. To the capacity of the three. That said, with the new grid code setting they may be more relaxed about it.

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slartybart avatar image slartybart commented ·
To update: selecting the G98 gridcode in the Multiplus settings seems to limit not just feed in, but production, so I’ve reverted to the G99 grid code and set the export limits elsewhere. However, I have now received my final ‘all’s good’ letter. The original principle was choosing an inverter under a 32amp capacity meant qualifying for the G99 fast track process, which allowed me to use the larger 8000vA model, despite being subject to a 16a export limit. Its notional capacity is 6.4kW. I also applied to install the bigger 10000vA model but was told no. The original application pointed out that the export limits are installer options and locked and therefore not changeable by the user (although here both are me). The use of an external meter (et112) in the system satisfied them my system would be compliant. Although I also sent them the G100 sheet (the one someone posted above), this wasn’t needed in the end.
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spazpeker avatar image
spazpeker answered ·

I have 2x 5k Multiplus in parallel for simplicity my drawing only shows one,

The export limit doesn’t change with more units.

I did get approved.

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hutch avatar image
hutch answered ·

G100 is 6 weeks away apparently.

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