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This gets complicated. The modern house could be using solar with batts,EV,HP,V2L,diverter. My issue for the moment is not how you prioritise this in consumption terms but how does one physically wire it up to cater for these different connections.

My next EV will have V2L, its not far off for every manufacturer even Tesla.

So could have 4 inputs Grid,PV,V2L and batts
and 5 outputs batts,car charging,house,HW diverter and HP

Are there 6-7kw hybrid inverters that could handle all that whilst still maintaining the FITS PV ?

Lets not go to how one would contol this unless relevant.

I intend fitting more PV whilst maintaining FITS but the next step has to include the above.

Nowty Towers does it with home batts, 2 x EVs, 3 x HPs, 2 x HW diverters. Only thing I don't have is V2L but if I did, I would use it to power a supplementary battery charger direct to the home batteries, so essentially an offgrid to ongrid power transfer. I have 3 systems of which 2 are on FITs and 1 is not, all single phase.

You have 3 main options.

1) Leave the FIT system alone and install an off grid system to power some loads, no need to tell anyone anything. I originally did this but can get complicated, I don't recommend doing this.

2) Replace the existing FIT inverter with a single large hybrid inverter, and a bi-directional generation meter, and wrestle with your FIT provider over the change of meter and agree a pro rata reduction in your FIT rate if adding more PV. Depends how well your FIT provider cooperates. Agree with DNO how big you can have and with G100 export limitation big ones (say 6kW) are now within reach and some even work in parallel, so really big systems can be installed. Either G99 fast track or G99 application to DNO.

3) Leave the FIT system alone and install a second inverter (hybrid) with batts and extra PV. No need to bother FIT provider. Agree with DNO how big you can have and with G100 export limitation big ones (say 6kW) are now within reach and some even work in parallel for even more power. Either G99 fast track or G99 application to DNO. (recommended option)

Option 3 can also be a battery inverter, and you DC couple extra PV onto the batteries using charge controllers, but essentially its the same thing.

There are tons of hybrid inverters out there now, LUX, Solis, Solax, Sunsynk, Growatt, ....................., etc.

I don't have any hybrid inverters as I'm running legacy SMA gear, but do have several PV inverters and a single battery inverter. If I was doing it all again I would be tempted by LUX hybrid ones as they are designed for parallel operation. A few on here have them.
https://luxpowertek.com/hybrid-inverters


Example of my system which is limited to the standard 3.68kW export (within 5 secs), and is still capable of extreme running, example running 12.2kW of house loads via PV and batts back in June 2022.

nowty wrote: ↑Sun Aug 20, 2023 7:44 pm
3) Leave the FIT system alone and install a second inverter (hybrid) with batts and extra PV. No need to bother FIT provider. Agree with DNO how big you can have and with G100 export limitation big ones (say 6kW) are now within reach and some even work in parallel for even more power. Either G99 fast track or G99 application to DNO. (recommended option)

Option 3 can also be a battery inverter, and you DC couple extra PV onto the batteries using charge controllers, but essentially its the same thing.

Yes, +1 to this. Attraction of having some PV via an MPPT is that it is slightly more efficient for charging whereas keeping the legacy FIT inverter is better for supplying the AC loads.

My DNO would not agree to more than 3.7kW inverter power which is quite restrictive. However in a recent simulated grid fail stress test I got up to 5kW output on battery alone before it all tripped out.

Doing this was prompted by an unexpected blackout when we lost the RCDs on both input and output of the Mulitplus - caused we think by a leaky ring on the 1972 Belling cooker.

Other results (when back on grid) were that the 32A cooker circuit is good for 10.6kW and the total passthrough can reach 13.6kW without tripping. I gave up at that point as the fan heater has been put away for the summer. DNO has recently confirmed the supply as 80A and approved a 12kW Vaillant Arotherm Plus HP (without any auxiliary heaters).

nowty wrote: ↑Sun Aug 20, 2023 7:44 pm Nowty Towers does it with home batts, 2 x EVs, 3 x HPs, 2 x HW diverters. Only thing I don't have is V2L but if I did, I would use it to power a supplementary battery charger direct to the home batteries, so essentially an offgrid to ongrid power transfer. I have 3 systems of which 2 are on FITs and 1 is not, all single phase.

Maybe a slight diversion, but do you need HW diverters if you are running a heat pump (for water as well as heat)? I thought it was better to use the Heat pump COP benefit, which should only get to worst case of 1 in the winter, which is the same as the diverter? Or have I missed something
I know that 1 or some(?) of your heat pumps are the air to air versions, which are completely separate.

richbee wrote: ↑Tue Aug 29, 2023 3:54 pm

nowty wrote: ↑Sun Aug 20, 2023 7:44 pm Nowty Towers does it with home batts, 2 x EVs, 3 x HPs, 2 x HW diverters. Only thing I don't have is V2L but if I did, I would use it to power a supplementary battery charger direct to the home batteries, so essentially an offgrid to ongrid power transfer. I have 3 systems of which 2 are on FITs and 1 is not, all single phase.

Maybe a slight diversion, but do you need HW diverters if you are running a heat pump (for water as well as heat)? I thought it was better to use the Heat pump COP benefit, which should only get to worst case of 1 in the winter, which is the same as the diverter? Or have I missed something
I know that 1 or some(?) of your heat pumps are the air to air versions, which are completely separate.

Since Electricty generated by PV is "free", I suspect that this maybe a case of use it or give it away to the grid. Clearly Nowty's 2xA2A HPs won't heat the DHW and iirc the other is a Water source HP relying on an underground stream which required significant groundwork as a foundation pile had been put through the centre of the concrete pipework. I don't know if the particular WSHP/GSHP is able to generate hot water.

Countrypaul wrote: ↑Tue Aug 29, 2023 4:12 pm

richbee wrote: ↑Tue Aug 29, 2023 3:54 pm

nowty wrote: ↑Sun Aug 20, 2023 7:44 pm Nowty Towers does it with home batts, 2 x EVs, 3 x HPs, 2 x HW diverters. Only thing I don't have is V2L but if I did, I would use it to power a supplementary battery charger direct to the home batteries, so essentially an offgrid to ongrid power transfer. I have 3 systems of which 2 are on FITs and 1 is not, all single phase.

Maybe a slight diversion, but do you need the HW diverters if you are running a heat pump (for water as well as heat)? I thought it was better to use the Heat pump COP benefit, which should only get to worst case of 1 in the winter, which is the same as the diverter? Or have I missed something
I know that 1 or some(?) of your heat pumps are the air to air versions, which are completely separate.

Since Electricty generated by PV is "free", I suspect that this maybe a case of use it or give it away to the grid. Clearly Nowty's 2xA2A HPs won't heat the DHW and iirc the other is a Water source HP relying on an underground stream which required significant groundwork as a foundation pile had been put through the centre of the concrete pipework. I don't know if the particular WSHP/GSHP is able to generate hot water.

Its a good question as to whether I need HW diverters as I have a HW HP (the GSHP from the underground river). I have the diverters from a historic point of view before I had any HPs, they were to heat my water and later to also heat 2 storage heaters and they still do.

In winter, and any other time when Solar PV is a scarce resource, I use the HP for the HW as its more efficient.

In summer I have an excess of PV generation but I am limited to 3.68kW export, so if I was to be more efficient and ran the HP all the time for HW I end up with more curtailment and that costs me FIT income. So better to use the diverters and maximise my generation and therefore my FIT income. Running on the immersions via the diverters also extends the life of the HP.

When heating my HW with my HP, the COP is lower at the top temperature end and it hammers the HP compressor as it works at a higher pressure. So I set the HP to trip out at 50 degrees and go the last few degrees with the immersions via the diverters in boost mode.

Thanks Nowty - that makes sense

Ken wrote: ↑Sun Aug 20, 2023 5:24 pm This gets complicated. The modern house could be using solar with batts,EV,HP,V2L,diverter. My issue for the moment is not how you prioritise this in consumption terms but how does one physically wire it up to cater for these different connections.

My next EV will have V2L, its not far off for every manufacturer even Tesla.

So could have 4 inputs Grid,PV,V2L and batts
and 5 outputs batts,car charging,house,HW diverter and HP

Are there 6-7kw hybrid inverters that could handle all that whilst still maintaining the FITS PV ?

Lets not go to how one would contol this unless relevant.

I intend fitting more PV whilst maintaining FITS but the next step has to include the above.

Did you ever get round to adding V2L to charge your batteries or power the house?