G83 pre install application

[claypole]

One scenario where G83/1 compliance and FIT band are clearly distinguished is where 3 phase is involved. G83/1 clearly allows you to output at 16A per phase, whilst the corresponding power output would obviously take you above the 4kw FIT band. I've been following this thread with interest and coming more and more round to the view that it is the inverter output that counts in both instances. For one thing, it is impossible to give a maximum output (dc) from an array. The sizes commonly referred to are only a nominal rating under test conditions. The manufacturing tolerance for most panels is +10% so the array output under std test conditions could already be 10% higher. If you then add cell temperatures below 25c or irradiance above 1000 the output could be higher still - how could you possibly define the max? The G83/1 certified inverter on the other hand is hard set to output maximum 16A. For G83/1 "fit and inform" surely this is the only information you need? Where it gets complicated is if you decide to make an application in advance because this form will ask for kva capacity. I would still say this figure is also governed by the inverter because again you can't give a definitive maximum output from the array. The Sunny Boy 4000TL supplied to UK is preset to comply with G83/1, maximum 16A and maximum 4000kva (which presumably would only occur when grid is at 250V). But why would you make a pre-application if your inverter is certified G83/1? I can see why people consider a nominal array >4kw is relevant due to the TIC / DNC questions on the FIT registration but surely in the case of the Sunny Boy 4000TL (and doubtless others, it's just that I'm only looking at this inverter) you can rightly declare both TIC and DNC as 4kw?

 

[TedM]

But why would you make a pre-application if your inverter is certified G83/1? I can see why people consider a nominal array >4kw is relevant due to the TIC / DNC questions on the FIT registration but surely in the case of the Sunny Boy 4000TL (and doubtless others, it's just that I'm only looking at this inverter) you can rightly declare both TIC and DNC as 4kw?

A pre-application under G83 is required in the case of multiple installs - stage 2.

Personally I agree completely with anyone who uses the inverter output for both TIC and DNC. The definition of "Eligible Installation" has to logically include the inverter - so that must also be included when calculating TIC and DNC.

 

[Worcester]

Here's the exact wording from e-on / Central Networks FIT application form:

What is the total installed capacity of your generator in kW or MW?
Note: Your unit’s capacity must not exceed 5MW or 2kW for a domestic micro CHP.
kW___________________ MW___________________
What is the declared net capacity of your generator in kW or MW?
kW___________________ MW___________________

They have used "TIC" and "DNC", so these words must be based on the DECC definitions, so the defining factor is, once again, the inverter.

Perhaps this explains how one of the big supermarlets was able to offer a 4.2kWp system for domestic installations.

What it also indicates is that to maximise the revenue for the 4kW FIT tarrif, you'll need to be G59 compliant...

@solarfred
Maybe I missed it, but I can't see anywhere in the MCS documentation where it says to use kWp of the panels.

. The MCS just oversee the whole process. They insist that the TIC or what is on the roof is "what is on the label" ie. add up all the wp of the installed modules and that is the TIC as they have been told by OFGEM that is the rule.

MCS is about proper process, not regulation or definition, they leave the specification of G83/1-1 etc up to the others.

As far as I can see what this all really means is that domestic installs will max out at 3.68 kW, usually being defined by the inverter capacity, not the specified panel output.

And for anything over 3.68kWp,

DNOs are allowed to use their discretion to accept a >16A per phase system under G83 terms...

... the protection settings should conform to G59/2

Gordon

 

[claypole]

A pre-application under G83 is required in the case of multiple installs - stage 2.

Personally I agree completely with anyone who uses the inverter output for both TIC and DNC. The definition of "Eligible Installation" has to logically include the inverter - so that must also be included when calculating TIC and DNC.

Ted, I would apprecaite your further opinion on the following: For a further install that included a 2nd inverter or where a different technology was involved (eg combining hydro and pv) at the same site then I believe stage 2 pre app would clearly be needed. But.. if just the number of panels was increased (lets say to combined 5kwp nominal array size) whilst still feeding the same G83/1 inverter I'm thinking no pre app would be required and indeed no notification at all since the inverter max rating has not changed. With regard to FIT my initial thinking was that this amendment would have to be declared but again if we use the inverter max power figure for the original MCS declared TIC and DNC then again nothing has changed. Is it a requirement under MCS registration to include in your schematic the specific number of panels and their nominal output figure? And if yes, then presumably you would have to declare an amendment. Any body else with a view on this? Anybody done it?

 

[TedM]

I have asked OFGEM about things like inverter changes to existing systems. Their reply was that once you had a registered system all you needed to do was ensure that you did not break any of the terms of your FiTs contract with the electricity supplier. Most of these have conditions running to 4-6 pages.

I believe that any changes, including increasing the number of panels even if this doesn't affect the G83 limit, would still need to be advised to the DNO in keeping with the 28 day after commissioning rule and to MCS and the supplier.

 

[solarfred]

Here's the exact wording from e-on / Central Networks FIT application form:

View attachment 4007
They have used "TIC" and "DNC", so these words must be based on the DECC definitions, so the defining factor is, once again, the inverter.

Perhaps this explains how one of the big supermarlets was able to offer a 4.2kWp system for domestic installations.

What it also indicates is that to maximise the revenue for the 4kW FIT tarrif, you'll need to be G59 compliant...

@solarfred
Maybe I missed it, but I can't see anywhere in the MCS documentation where it says to use kWp of the panels.
MCS is about proper process, not regulation or definition, they leave the specification of G83/1-1 etc up to the others.

As far as I can see what this all really means is that domestic installs will max out at 3.68 kW, usually being defined by the inverter capacity, not the specified panel output.

And for anything over 3.68kWp,

Gordon

Gordon,

I spoke to the MCS staff at Ecobuild to try and nail down the issue and that is what I was told.