Considering more solar and a battery

Screwdriva

Reed_Richards said:

Screwdriva said:

I would and have expanded my system to the maximum with no regrets. Hard to say for certain but the installers I use have had great success with PW3 DNO approvals. 

But I presume all these installers are in much the same area?  My impression is that different DNOs, and probably considering different locales, can take quite different views.  Is there any database you can look up to find out what others in your neighbourhood have been allowed to install?    

Incorrect. I do my best to help individuals across England & Wales and have similar (albeit very recent) results across all DNOs (except South Devon, where the grid infrastructure limits export limits for some reason). Another great example is the 2024 approval for 16kW system (1 X 10kW + 1 X 6kW SolarEdge inverter) in Colchester. Both inverters connect to an GE All in One battery and 44 Eurener bifacial panels. 

UKPN is the best of them all. When I met with Tesla Solar, they shared they  had invested resources in educating utility companies on the benefits of their systems and it is paying dividend for them. 

NedS

Martyn1981 said:

Hi Ned, not important, just pondering, but are you still planning on dropping the Fox inverter and putting both strings through the PW3, or going to see what the DNO say, and work from there?

I assume that the PW3 could grab the export from the Fox (actually export from the house) and put it in the battery, along with the direct PV generation on its DC side. But there would then be DC to AC to DC losses.

Still thinking out loud, I suppose you must be removing the Fox inverter, or the DNO will add all the PV together .....just curious as this is an unusual query/decision, but one I can see happening more and more in the future as folk upgrade/revise existing systems.

@Martyn1981 Yes, I have options.

We already have a Fox ESS 3.0kW inverter with exiting solar array.

We are adding a further 3.56kWp and Tesla PW3 with 11.04kW output rating.

My preferred (although I'm happy to be persuaded otherwise if anyone has a clear argument to the contrary) solution is to disconnect the existing inverter and wire that solar PV string into the PW3 (DC coupled).

If I leave the existing Fox inverter, then I'd be requesting DNO permission for the existing 3.0kW plus an additional 11.04kW for the newly added PW3 (with newly added 3.56kWp added to the DC side), so I'd need a total of 14.04kW, or I would have to limit the PW3 output.

If I remove the existing Fox inverter and put both the existing solar array and new solar array (7.2kWp in total) into the PW3, then because they are DC coupled, I only need export limit for the PW3, so 11.04kW max.

There are pro's and con's for leaving half the solar AC coupled, but mostly I'd prefer it DC coupled to maximise our allowable peak discharge rate from the battery. If the DNO were to only give me 6.68kW, if 3.0kW solar is still AC coupled, I would be limited to 3.68kW discharge from the PW3 which may not be enough to always power the home when multiple appliances are turned on. Having all of the solar DC coupled gives me the full DNO permitted limit, up to the capability of the battery (11.04kW)

NedS

When I was initially discussing with the installer, who has experience with DNO applications in my neighbourhood (they have done a few properties just around the corner), I asked how much they thought the DNO might offer, and they immediately replied 6kW so I'm assuming that is what other local residents were offered. Maybe they had less solar though (6kWp), as that is the driving force behind wanting 7kW DNO export.

greenbee

I've just had DNO approval for an additional 5kW export, taking my total up to 10kW, so am going to go ahead with the installation (we've been given a commissioning deadline of early May). I'm only a couple of miles from an interconnector, and surrounded by solar and wind farms, so I suspect that my installation is inconsequential compared to what else they have going on!