Additional solar and battery storage

[Nickfromwales]

25 minutes ago, Dillsue said:

Still needs a a bit of G99 begging for the inverter unless the new system is off grid

Not quite, more a statement of compliance as at that stage you'll be non MCS ( so no export payment eligibility ) and setting the hybrid inverter / declaring ZERO export  At the most the DNO will ask a representative to attend and witness the zero export limitation in practice and sign you off. What you do after that will be of ( ahem ) zero interest to them. You could have 50kWp of solar and 50kWh of battery, they would not care one jot as it would all be on the D/C side.  

[Ronski]

2 hours ago, Dillsue said:

Just looking at your figures, youre listing a 5kw SE inverter, a Victron 5.5kw charger and the 4kw existing system which totals up 14.5kw of potential export. Thats a fair bit of export to get approved so might be worth having an informal chat with your DNO to see what they think before you submit the G99??

 

Already tried that with an informal email to sound things out, I got a reply back saying not something they could answer and I would need to make a G99 application. Would a phone call likely get me any more info? DNO is UK Power Networks.

Edit: If they don't approve the full amount, do they tell you what they would approve?

 

 

2 hours ago, Nickfromwales said:

Yup, hence my suggestion of hybrid and D/C for the new additions. Needs no begging / going on bended knee. One less A/C to D/C to A/C conversion also, so more efficient charging the D/C batteries from the D/C from the roof.

 

My understanding is a DC battery would only charge from the array it is connected to, and the excess power from the existing array would still get exported, is my understanding correct?

Edited May 2, 2022 by Ronski

[Dillsue]

1 hour ago, Nickfromwales said:

Not quite, more a statement of compliance as at that stage you'll be non MCS ( so no export payment eligibility ) and setting the hybrid inverter / declaring ZERO export 

As the OP already has a FIT system thats likely to have been declared as being at the 16A allowable export limit, surely the DNO is going to be asking questions if you send in another "statement of compliance" without a G99 application or manufacturer declaration of zero export? Have you actually done this and had it accepted?

 

 

[Dillsue]

11 minutes ago, Ronski said:

Would a phone call likely get me any more info? DNO is UK Power Networks.

Edit: If they don't approve the full amount, do they tell you what they would approve?

 

 

 

My understanding is a DC battery would only charge from the array it is connected to, and the excess power from the existing array would still get exported, is my understanding correct?

Our DNO was happy to discuss technical detail and I think/hope we agreed the scheme that our G99 application has formalised.  Cant speak for UKPN but SPEN were great, so far.

 

Ive no idea what other manufacturers offer but have a look at the SE Storedge system to see what is possible... charge from PV, charge from the grid, charge from another inverters output all on DC coupled batteries so they dont add to potential export figures. 

[Ronski]

Those Storedge batteries are rather expensive, Midsummer have the 10kWh battery for £5850, which is almost double the price of the GivEnergy 9.5kWh battery 😲

 

I was reading the Storedge instructions, this safety warning got me "Do not place any combustible items within less than 2.5 m / 8 ft of the Battery" hmmmm, server room is also a cloakroom, so full of coats, garage is full of all sorts of combustible stuff, just how many are installed, or remain in a 2.5m clear area 🤔

 

At least it actually has a built in fire extinguisher.
 

[Dillsue]

Yep, an empty garage is probably a better bet but that would be the place for any battery pack, in my world anyway.

 

I had another look at PV connectivity when using Storedge to charge from another inverters output and I dont think you can do it so definitely check with SE before making any decisions, if you can get your head round the cost!!

[Nickfromwales]

6 hours ago, Dillsue said:

As the OP already has a FIT system thats likely to have been declared as being at the 16A allowable export limit, surely the DNO is going to be asking questions if you send in another "statement of compliance" without a G99 application or manufacturer declaration of zero export? Have you actually done this and had it accepted?

 

 

In addition to, not in place of  Compliance, as in you are using a recognised piece of equipment that the manufacturer has indicated can be G99 ( G100 ) registered / recognised / compliant.

Not done this myself, yet, but as I have just ordered a load of my own kit for my zero-export install I have been power reading all of the solar / off-griddy forums where the inverter I want to use is mentioned, and has been accepted by the DNO repeatedly in the exact same circumstances. I wouldn't state things here if they couldn't be done. 

[Nickfromwales]

6 hours ago, Ronski said:

My understanding is a DC battery would only charge from the array it is connected to, and the excess power from the existing array would still get exported, is my understanding correct?

Yes. My ramblings are based on your wish to add to the system. So, as per my previous ( and that of others ) timing appliances to run strategically ( most washing machines and dishwashers have delay timers these days ) and utilising the existing array to the max would be the way forward for getting all the export dialled down. Also seriously consider the installation of an UVC for DHW ( direct to bathing or as pre-heated water to the combi inlet ) which would be a good option for you to get the hot water for free for a lot of the year, dropping you on demand gas consumption for one, but also, dependant on the size of the cylinder, would provide you with somewhere you could install a second immersion to act as an energy dump when the batteries are full.

I've yet to get answers to questions about possibly using a FiT systems export to power a battery charger for the batteries on the hybrid side via an diversion controller. One of my wackier ideas, but I'm always thinking what can be done that hasn't been done before.   

[Ronski]

@Nickfromwales Do you have a link to a build thread of what you are intending on installing?

 

Our gas bill isn't too bad, between February 2021 and February 2022 what we used at current prices equates to £600 of gas + £100 standing charge. Just had a quick look at costs of cylinders and they are not bad, its something to consider as I could install myself back where the original hot water tank was. One consideration is that if installing a battery of sufficient capacity then there would be a lot less spare solar energy to heat the water though.

 

[Dillsue]

8 hours ago, Nickfromwales said:

In addition to, not in place of  Compliance, as in you are using a recognised piece of equipment that the manufacturer has indicated can be G99 ( G100 ) registered / recognised / compliant.

Not done this myself, yet, but as I have just ordered a load of my own kit for my zero-export install I have been power reading all of the solar / off-griddy forums where the inverter I want to use is mentioned, and has been accepted by the DNO repeatedly in the exact same circumstances. I wouldn't state things here if they couldn't be done. 

Im not questioning whether things can be physically done, but trying to understand the process that you are using to do things, above board. I took your previous posts as saying that you could put in an export limited system(zero export) without using the G99+G100 application process. If its not through the G99+G100 route then intrigued to know what other routes there are to legitimately connect to the grid??

[Ronski]

I spoke to the DNO today, the guy I spoke to suggested I put it in an email, when I said I already had, and the reply was just to submit a G99, he said to resend it and add that I'd spoken to him, so we'll see what comes back.

[Dillsue]

17 hours ago, Ronski said:

I spoke to the DNO today, the guy I spoke to suggested I put it in an email, when I said I already had, and the reply was just to submit a G99, he said to resend it and add that I'd spoken to him, so we'll see what comes back.

Thats more like it. Hopefully theyll informally give you some idea of the local constraints and what youll likely be able to connect.

[Ronski]

I had a reply from the DNO today, much more useful information this time.

 

Quote

Many thanks for your enquiry. I’ve reviewed your email and our records for the local network. Based on your close proximity to the substation (and therefore the low impedance of the circuit at your connection point) installing an additional 4.8kW of solar PV should not cause any voltage rise issues and your PV application ought to be approved without any problems.

 

I’m not sure whether there is any intention to export to the grid from the battery? If there is no intention to use the battery to export then you’d just need to submit a copy of the device’s G100 type-test certificate with the commissioning submission. If the battery is connected on the DC side of the inverter then we can disregard it as a potential issue as any export to the grid would be limited by the inverter size.

 

There may potentially be a voltage rise issue if the battery was connected on the AC side of the system and export from the battery coincided with that from the PV system. If you’d like the facility to use the battery for export to the grid at peak times then I’d suggest that a G100 compliant Export Limiting Scheme (set to the equivalent PV inverter rating) would be appropriate in this instance.

 

I hope that this makes sense but do contact me if you have any queries or would like further details on any of the points raised.

 

I'm pretty sure I'm going to need an AC connected battery, so the battery can be charged from both arrays, so what dos the fourth paragraph mean, installation wise? Is that fairly straightforward to achieve, or very expensive?

[Wil]

God what a generally useful response from a DNO. I wish WP responded with anything other than ‘computer says no’!! The G100 export limiting just means both your AC battery inverter and the PV inverter would need to be set to limit the export to under 4.8kW or whatever your agreed limit was. As long as you buy inverters that are G100 cert and is set up by someone who can prove the limiting is in place if the DNO wish to see it, then you should be fine.

 

W

[Ronski]

@WilThanks, that was the second response after I phoned them. First response was to complete a G99 application, I then phoned them and the guy said to put it in an email, he seemed surprised when I said I already had and told him what reply I got.

[Ronski]

I’ve been watching more of Andy’s off grid garage journey, and it occurred to me at the weekend, from a simplicity and cost point it view it would be better to use four MPPT 150/35 charge controllers, with three panels on each string. Whilst this won’t work as well as SolarEdge optimisers with regards to shading, it probably wouldn’t be far behind, problematic panels could have Tigo optimisers fitted if need be.

 

This approach would reduce maximum usable power, as the new array and batteries would be just through the Multiplus II, which unless I went up a size (a lot more expensive) would be limited to 4kw output, but it’s not often we’d exceed that anyway.

 

The existing array could be run in to the critical loads output, and thus both arrays would keep running in an extremely rare power cut, supplying power and charging the batteries. The fridge freezers (on their own circuit already), lighting and perhaps some emergency sockets could be run off the critical loads circuit. This would of course require two new cables from the garage.

 

Would the Multiplus II be able to handle the existing 4kw array on the critical loads circuit and would we be able to use say 7kw of solar if both arrays was producing 3.5kw?

 

What's you're thoughts on the above?

 

 

[Ronski]

I've had approval from the DNO for an additional 9.4kw export, making a total export of 13.08 kw including the existing system.

[Roger440]

On 06/06/2022 at 20:44, Ronski said:

I’ve been watching more of Andy’s off grid garage journey,

 

Are you able to link to this please for those of us not on the inside loop?

[Ronski]

@Roger440 Sure, here you go https://www.youtube.com/c/OffGridGarageAustralia/videos

 

[Roger440]

22 hours ago, Ronski said:

@Roger440 Sure, here you go https://www.youtube.com/c/OffGridGarageAustralia/videos

 

 

Thanks

[Ronski]

Just noticed in my DNO approval there is a zero in brackets, when I put the G99 application in it was for 5kw PV inverter and 4.4kw AC connected battery, here's what the letter states.

 

Quote

No physical work required

I am pleased to confirm that UK Power Networks is able to provide the Premises with an Export Capacity of an

additional 5kW PV & 4.4(0)kW Battery without UK Power Networks having to carry out any construction or electrical

works.

 

Any idea what the 0 in brackets means?

 

Since sending in the application my system design has changed, I'm now going to have a single inverter with DC connected batteries, total inverter power will be either 6400w or 8000w. Since both are lower than the combined 5+4.4 is the G99 still valid?