Solar PV advice

[sharpener]

Thanks for explaining sharpener. Much appreciated.

So the power generated by the panels connected to the charge controllers would be sent straight to the batteries and not go into the inverter?

Yes.

The power generated would then not be able to be used directly by the house as it would be independent from the SunSynk inverter?

No, it would charge the batteries and then they would discharge through the inverter to supply the house. Or go straight to the inverter if the batteries were full.

How do you view how much they are generating, etc if not talking to the SunSynk inverter?

Depends on the charge controller, could be interfaced to the Sunsynk, could be a third-party integration e.g. via Modbus or Home Automation, could be a separate readout from the charge controller either local or over the web..

If that's correct, will this have any negative affects on how the SunSynk inverter, batteries work together? Or how they power the house, etc?

Simplest control stragegy is the charge controller seeks to achieve/maintain a defined float voltage on the battery (?3.45V/cell or something, my Pylontecs are 3.47 to 3.50V when fully charged), subject to a charge current limit you can define. This adds to the current the Sunsynk can draw to feed the house and/or prolong its duration. No changes to what the house sees apart from that.

The Sunsynk might be upset by seeing changes in State of Charge it did not know about/cannot rationalise, or the reported values may not be correct. If there is a Sunsynk user group on the web someone on there will know if you can do this. Not my field really, in Victron world it is all done for you, you get what you pay for(!). Have customised it a bit by writing flows in NodeRed. Family also gave me an Arduino kit but I have yet to get to grips with it properly. HP install has kept me busy this year.

[Fintray]

Thanks for explaining sharpener. Much appreciated.

So the power generated by the panels connected to the charge controllers would be sent straight to the batteries and not go into the inverter?

Yes.

The power generated would then not be able to be used directly by the house as it would be independent from the SunSynk inverter?

No, it would charge the batteries and then they would discharge through the inverter to supply the house. Or go straight to the inverter if the batteries were full.

I can't quite agree with that advice, as if the charge controllers are supplying power that will be used by the inverter as it's just another source of 48V DC. If they are supplying more than the house load the balance will be charging the batteries and if not, so much would be drawn from the batteries to make up the difference.

[Richard77]

Thanks Fintray, sharpener and everyone else.

I think I am getting my head around all this now, thanks.

I think I am correct in thinking that the 8.8kw SunSynk should be fine to handle the east and west facing panels on its own.

SunSynk 8.8kW:
PV input voltage: 370v (125v-500v)
MPPT range: 150-425v
PV input current: 26A + 26A
Max PV Isc: 34A + 34A
Max DC input: 10400w

455w Aiko's:
Voc = 40.79v (+2-3v cold temp) so 44v to be safe.
Isc = 14.22A

West: 2 strings of 9 panels (18 total) to MPPT1 = 396v each string and 28.44A (under the max 34A PV Isc, but might lose a tiny bit of generation on the odd day as over the 26A pv input current?)
8.19kW array -> ~5900kWh yearly

East: 2 strings of 8 panels (16 total) to MPPT2 = 352v each string and 28.44A (so ok?)
7.28kW array -> ~5400kWh yearly


With regards to the victron charge controllers:
Could possibly get 6x 455w Aiko's on south facing roof so 264v and 14.22A if on one string? So it's one victron charge controller per string? Can anyone suggest a model number of a controller that could work?
Similar for the garage, so putting 6x 455w Aikos on would I need another separate victron charge controller for them? Are you can buy a victron that accepts 2 strings?

Cheers

[sharpener]

West: 2 strings of 9 panels (18 total) to MPPT1 = 396v each string and 28.44A (under the max 34A PV Isc, but might lose a tiny bit of generation on the odd day as over the 26A pv input current?)
8.19kW array -> ~5900kWh yearly

East: 2 strings of 8 panels (16 total) to MPPT2 = 352v each string and 28.44A (so ok?)
7.28kW array -> ~5400kWh yearly


With regards to the victron charge controllers:
Could possibly get 6x 455w Aiko's on south facing roof so 264v and 14.22A if on one string? So it's one victron charge controller per string? Can anyone suggest a model number of a controller that could work?
Similar for the garage, so putting 6x 455w Aikos on would I need another separate victron charge controller for them? Are you can buy a victron that accepts 2 strings?

Cheers

Check out this Victron MPPT calculator https://www.victronenergy.com/mppt-calculator and see also link to PV matching article https://www.victronenergy.com/blog/2014 ... egulators/

Looks like their cheapest 150/45 model will do for 3 series 2 parallel arragement of 6 Aikos with some clipping of the max output (this slight over-panelling is usually a good economic choice, cf my own installation below). You would need one for each array unless they have identical orientation in which case you could put them all on a single 150/85. Or you might find another brand with two separate trackers.

[nowty]

You would need one for each array unless they have identical orientation in which case you could put them all on a single 150/85. Or you might find another brand with two separate trackers.

In practice parallel strings don't need to be in the same orientation, several strings at Nowty Towers work like that, they just need to be identical voltage. And that works for both grid tie inverters and DC charge controllers.

Lesson 6 from here,
https://mcelectrical.com.au/blog/solar- ... wer%20loss.

And a tech paper form Fronius,
https://www.google.com/url?sa=t&rct=j&q ... i=89978449

"When a PV generator has more than one tilt angle and/ or orientation it is recommended to connect those different generators to independent MPP trackers. Several investigations [1] [2] have shown that, under certain circumstances, even such generators can be connected to a single MPP tracker."

[Richard77]

Thanks sharpener and nowty.

I think my last question for the time being (sorry!)

If I go down the route of getting another small inverter (say a SunSynk 3.6/5.5kw) and connect the extra panels on south/garage roofs to it. Then connect that smaller inverter (slave) to the SunSynk 8.8kw (master) will it behave as one big inverter or 2 separate inverters?

Batteries connected to the master, master connected to the house, slave connected to master?

Thanks.

[resybaby]

Cant help with the master/slave configuration query (my sunsynk (cough) )manual' seems to say its quite simple to set up), but if your introducing another invertor into the mix, on top of the 8.8kw one, i think you really should bottom whether the DNO will approve of all that kit.

[Richard77]

Cant help with the master/slave configuration query (my sunsynk (cough) )manual' seems to say its quite simple to set up), but if your introducing another invertor into the mix, on top of the 8.8kw one, i think you really should bottom whether the DNO will approve of all that kit.

Thanks resybaby....

I think from my reading up, it operates as one big inverter and seems quite straightforward to parallel them and setup.

All this is hypothetical at the moment I suppose. Waiting to see what the DNO says. They might turn around and say 3.68kw max, then I'm f@£#ed!

[sharpener]

Cant help with the master/slave configuration query (my sunsynk (cough) )manual' seems to say its quite simple to set up), but if your introducing another invertor into the mix, on top of the 8.8kw one, i think you really should bottom whether the DNO will approve of all that kit.

Thanks resybaby....

I think from my reading up, it operates as one big inverter and seems quite straightforward to parallel them and setup.

All this is hypothetical at the moment I suppose. Waiting to see what the DNO says. They might turn around and say 3.68kw max, then I'm f@£#ed!

G99 simple process is limited to 32A export, you have the potential to exceed that. I have just applied under the SGI-3 category https://connections.nationalgrid.co.uk/ ... track-g99/ to increase my exports to 32A and succeeded, but that is on the basis that I have got built-in G100 export limiting which you would need. Check if the Sunsynk master-slave setup supports it.

Advantage of DC connection via MPPTs is it avoids much of these limitations, if @nowty is correct then you could get away with 1 x Victron 150/85 or similar to charge yr massive battery even if you were only to have a 3.68kW AC inverter.

[resybaby]

Thanks resybaby....

I think from my reading up, it operates as one big inverter and seems quite straightforward to parallel them and setup.

All this is hypothetical at the moment I suppose. Waiting to see what the DNO says. They might turn around and say 3.68kw max, then I'm f@£#ed!

Yes mate, thats exactly what happened to me