Adding more panels - DC fed to existing batteries?

[Mart]

Its DNO and FIT friendly.

If you do this, the only thing I recommend is set the charge controller charge voltage slightly lower (1V or 2V) than that of your Sofar so they both don't try and whack full power into the batteries together when the batteries get close to full charge.

The only thing is the stats on the Sofar will be wrong, but generally that does not affect its operation.

Hiya Nowty. I'm really keen on the DNO friendly bit.

I've been stumped trying to get my small groundmount steep pitch south facing idea going. I can't add more independent PV as I'm at the DNO limit, and I can't add to my existing Solaredge system, as every installer I've asked is unhappy to add a long DC run from the existing 3.58kWp system to the new panels, and back.

So my idea was that if I got a DNO approved battery setup, whose certification won't allow export, then I could piggy back off that with a DC connection from the PV. I've noticed the Givenergy inverter/batt kits, the hybrid versions. So can I triple check, that the PV wouldn't be grid tied, so to speak, raising issues with the DNO, but would instead be a feed to the battery, whose AC side would be, as you put it, 'DNO friendly'?

I appreciate that when full, the inverter would stop taking gen from the PV, but I'm thinking of winter gen, and possibly getting 30(ish) kWh's of batts to possibly use as a BEV buffer, and a for daytime use of the A2A units via night tariff leccy in the winter. Am I misunderstanding how the DNO 'stuff' works, and / or missing other crucial details. [Not worried about the PP for PV, I'll box it off as a small storage unit, for ladders, garden furniture etc. Hoping for 4-6 panels, so 1.5kWp to 2kWp.]

Givenergy 5.0kW Hybrid inverter / 9.5kWh batts

Givenergy 5.0kW Hybrid inverter / 9.5kWh batts

[nowty]

Its DNO and FIT friendly.

If you do this, the only thing I recommend is set the charge controller charge voltage slightly lower (1V or 2V) than that of your Sofar so they both don't try and whack full power into the batteries together when the batteries get close to full charge.

The only thing is the stats on the Sofar will be wrong, but generally that does not affect its operation.

Hiya Nowty. I'm really keen on the DNO friendly bit.

I've been stumped trying to get my small groundmount steep pitch south facing idea going. I can't add more independent PV as I'm at the DNO limit, and I can't add to my existing Solaredge system, as every installer I've asked is unhappy to add a long DC run from the existing 3.58kWp system to the new panels, and back.

So my idea was that if I got a DNO approved battery setup, whose certification won't allow export, then I could piggy back off that with a DC connection from the PV. I've noticed the Givenergy inverter/batt kits, the hybrid versions. So can I triple check, that the PV wouldn't be grid tied, so to speak, raising issues with the DNO, but would instead be a feed to the battery, whose AC side would be, as you put it, 'DNO friendly'?

I appreciate that when full, the inverter would stop taking gen from the PV, but I'm thinking of winter gen, and possibly getting 30(ish) kWh's of batts to possibly use as a BEV buffer, and a for daytime use of the A2A units via night tariff leccy in the winter. Am I misunderstanding how the DNO 'stuff' works, and / or missing other crucial details. [Not worried about the PP for PV, I'll box it off as a small storage unit, for ladders, garden furniture etc. Hoping for 4-6 panels, so 1.5kWp to 2kWp.]

Givenergy 5.0kW Hybrid inverter / 9.5kWh batts

Givenergy 5.0kW Hybrid inverter / 9.5kWh batts

The inverter your talking about would be a G99 application, but if you bought the 3.6kW version it would be a G99 fast track application. With regards to panels on a hybrid inverter (second inverter), I used to think that was not allowed but others have certainly had theirs approved via G99 fast track.

What this thread is more about is if you've already got a legal PV system plus a legal battery only system. Then can you add some more PV to the battery stack via a separate 48V charge controller. The answer to that is generally yes, as long as it does not mess up the G100 operation of the existing system, hence why I suggest setting the charge controller charging voltage to a lower limit than the grid tied battery inverter.

[Mart]

Many thanks Nowty. I had my application to be part of a V2G trial turned down in 2020 because of the potential excess. The V2G kit at that time, hadn't gotten G100 (I think) certification, so the DNO added the V2G export to the PV export, and said - "Hell NO!" To make matters worse, they also said that looking at my location, and the fact our house is on the end of a spur, I shouldn't have been granted 5.9kW export permission back in 2012, for my second PV system, that it was a mistake, but they weren't minded to revoke it ...... so obviously I don't want to do anything that might rock the boat.

Hence why I want to piggyback of a battery certification, that prevents export, or limits total export (including PV), to an acceptable limit.

I'm also thinking that I should wait another year, as things in the PV and battery world seem crazee at the moment.

Thanks again.

[nowty]

Many thanks Nowty. I had my application to be part of a V2G trial turned down in 2020 because of the potential excess. The V2G kit at that time, hadn't gotten G100 (I think) certification, so the DNO added the V2G export to the PV export, and said - "Hell NO!" To make matters worse, they also said that looking at my location, and the fact our house is on the end of a spur, I shouldn't have been granted 5.9kW export permission back in 2012, for my second PV system, that it was a mistake, but they weren't minded to revoke it ...... so obviously I don't want to do anything that might rock the boat.

Hence why I want to piggyback of a battery certification, that prevents export, or limits total export (including PV), to an acceptable limit.

I'm also thinking that I should wait another year, as things in the PV and battery world seem crazee at the moment.

Thanks again.

So depending on what you already have permission for, which sounds like more than the standard set up. And if you have say two inverters, the second not on FITs. You could simply swap that one with a hybrid version of the same power and job done. Then add batteries and more Solar PV.

Whats your current set up, PM me if you want.

[Mart]

Many thanks Nowty. I had my application to be part of a V2G trial turned down in 2020 because of the potential excess. The V2G kit at that time, hadn't gotten G100 (I think) certification, so the DNO added the V2G export to the PV export, and said - "Hell NO!" To make matters worse, they also said that looking at my location, and the fact our house is on the end of a spur, I shouldn't have been granted 5.9kW export permission back in 2012, for my second PV system, that it was a mistake, but they weren't minded to revoke it ...... so obviously I don't want to do anything that might rock the boat.

Hence why I want to piggyback of a battery certification, that prevents export, or limits total export (including PV), to an acceptable limit.

I'm also thinking that I should wait another year, as things in the PV and battery world seem crazee at the moment.

Thanks again.

So depending on what you already have permission for, which sounds like more than the standard set up. And if you have say two inverters, the second not on FITs. You could simply swap that one with a hybrid version of the same power and job done. Then add batteries and more Solar PV.

Whats your current set up, PM me if you want.

Thanks Nowty, I probably will PM you at some point in the future, when the World is slightly less crazee.

My current set up is 3.58kWp ESE on a 3.68kW capped Solaredge inverter, and a totally separate 2kWp WNW on a 2.2kW Solaredge inverter. Both FiTs, 2011 and 2012 respectively [Edit - Just added an autosig. M]. The DNO gave permission for the sum of the inverters, so a potential (theoretical) max export of 5.9kW.

Hence why I thought I could install an AC side battery, so long as it can't export, or export on top of the PV. I doubt I'll want it to export, but assume there's an accreditation that gets approval where it won't allow total export from the property to exceed XkW's. I'm thinking 3.68kW, not 5.9kW, in order to avoid pee'ing off the DNO in any way whatsoever. And then by utilising a hybrid inverter for the battery storage, I could then shove in a DC feed from my long wished for steep south PV groundmount.

To be clear, I'm not trying to do anything naughty, dodgy, or even rule stretching, just trying to find a DNO approved route for the extra PV by ensuring it's not got any export route to it, certainly no direct export route. As I mentioned, hiding (maybe not the right word), perhaps sheltering the PV behind the battery's DNO certified technology approval, that prevents export. I assume that's a thing, otherwise the theoretical battery export (inverter rating) would have to be added to the PV inverters, in any home, not just mine, which would make installing a battery difficult?

[nowty]

Many thanks Nowty. I had my application to be part of a V2G trial turned down in 2020 because of the potential excess. The V2G kit at that time, hadn't gotten G100 (I think) certification, so the DNO added the V2G export to the PV export, and said - "Hell NO!" To make matters worse, they also said that looking at my location, and the fact our house is on the end of a spur, I shouldn't have been granted 5.9kW export permission back in 2012, for my second PV system, that it was a mistake, but they weren't minded to revoke it ...... so obviously I don't want to do anything that might rock the boat.

Hence why I want to piggyback of a battery certification, that prevents export, or limits total export (including PV), to an acceptable limit.

I'm also thinking that I should wait another year, as things in the PV and battery world seem crazee at the moment.

Thanks again.

So depending on what you already have permission for, which sounds like more than the standard set up. And if you have say two inverters, the second not on FITs. You could simply swap that one with a hybrid version of the same power and job done. Then add batteries and more Solar PV.

Whats your current set up, PM me if you want.

Thanks Nowty, I probably will PM you at some point in the future, when the World is slightly less crazee.

My current set up is 3.58kWp ESE on a 3.68kW capped Solaredge inverter, and a totally separate 2kWp WNW on a 2.2kW Solaredge inverter. Both FiTs, 2011 and 2012 respectively [Edit - Just added an autosig. M]. The DNO gave permission for the sum of the inverters, so a potential (theoretical) max export of 5.9kW.

Hence why I thought I could install an AC side battery, so long as it can't export, or export on top of the PV. I doubt I'll want it to export, but assume there's an accreditation that gets approval where it won't allow total export from the property to exceed XkW's. I'm thinking 3.68kW, not 5.9kW, in order to avoid pee'ing off the DNO in any way whatsoever. And then by utilising a hybrid inverter for the battery storage, I could then shove in a DC feed from my long wished for steep south PV groundmount.

To be clear, I'm not trying to do anything naughty, dodgy, or even rule stretching, just trying to find a DNO approved route for the extra PV by ensuring it's not got any export route to it, certainly no direct export route. As I mentioned, hiding (maybe not the right word), perhaps sheltering the PV behind the battery's DNO certified technology approval, that prevents export. I assume that's a thing, otherwise the theoretical battery export (inverter rating) would have to be added to the PV inverters, in any home, not just mine, which would make installing a battery difficult?

Unfortunate both inverters are on FITs, so you cannot just simply replace one with a hybrid, well you can if FIT provider agrees, see my option 2.

Your options,

1) Apply G99 for a zero export battery inverter, fast track wont apply because your already over 3.68kW inverter power and as the DNO made a mistake, I would not go down this route in case they decide to undo that mistake.

2) It is possible to swap one of the inverters, say the 3.68kW one with another 3.68kW hybrid inverter so you can add batteries and arrange with your FIT provider to change the generation meter for a bi-directional one so any import from the grid to charge the batteries will be deducted from the generation. In this way there will be no DNO involvement, just agreement with your FIT provider. But you wont be able to add any more panels unless FIT provider allows a pro-rata dilution rate to your FIT payments.

3) I would normally say don't do the OffGrid thing like I used to do, but in your case it may well work for you, especially if your planning to use it as a buffer to charge the EV or time shift cheap slot to run a single A2A HP. There are now some all in one relatively cheapo units which will do this for you.