Dual inverters

[Sebastian G]

Hey,

I am looking to install new solar system and I have received a good proposal, the installer recommends to install 2 Inverters 1 Fox ESS 1 x KH10 to cover 3 different roofs with 6 PV on each side house and 1x FoxESS F Series 3.6kw Inverters for garage roofs.

Now i am getting bombarded with solar companies trying to get my business and some are telling me that the 2nd Inverter will not charge the battery and would also need to be a hybrid Inverter ? Installer told me that smaller F series Inverter will be sync with the hybrid and both will charge the same battery system.

I am going with 2x Fox ESS EP11 10kw batteries for the system. I think it will all be sync and should all work if installed at the same time right ? Also some are telling me that I will be fine with just 1 Inverter, because my roofs are facing the same orientation as on the house and garage ? I have attached the layout for better visualization.

So two questions really, do I need 2 Inverters and will both charge the batteries and if I can get away with just 1 Inverter (1 x KH10 ) ?

Thanks for all

[Will]

Hello,

Good news, the KH10 with two EP11 will also be able to charge from surplus solar generated by your garage string only inverter. Those installers who say it won't work clearly don't know what they're talking about.

So to confirm, go with one KH hybrid with the two batteries connected and the F series string inverter for the solar only array, which WILL be able to see seen by the KH and hence charge the battery. I personally do this and have done a lot of installs with a combination of string and hybrid inverters working great.

[ADJ]

Hi Will, I am in a bind due to G99 restrictions in the UK looking into a similar albeit smaller set up -

I am planning a 5kw H1G2 with 2 EP6 batteries with 2 strings (East/South facing arrays) and 1 S2500 string inverter with a west facing array.

Will this work OK (ie the H1G2 will use generation from all 3 roofs and deliver from battery storage to support loads?

Both inverters will be supplied from the same AC circuit.

[aaronlukemarshall]

Quick question on dual setup: In similar fashion I want to do the same as the above post, I have got a H1-G2-5kW covering the house arrays, but I would like to add a garage roof F series inverter with 5 panel PV array either side. But my max export rate is G99 limited to 5kW, how do I set that across both inverters so they both don’t go over the 5kW limit combined? TIA.

[Dave Foster]

When you have a hybrid (or AC) running with a second solar only inverter, this isn’t what you would describe as parallel mode. Parallel mode is where you have 2 hybrid inverters that each want to be in control of the loads, without them being connected in parallel mode they will fight continuously. For parallel (the inverter must support that feature i.e. gen 2 H1 and KH), there is a physical ‘parallel’ comms connection between them and only one of them has the meter (or CT). It shares that information with the second hybrid inverter and they will load balance across themselves as needed.

So back to your question (last 2 posts)

When a hybrid inverter is running with a second PV only inverter, you have to connect a second CT to the CT2 connection of the hybrid and the CT clamp is clamped to the live feed from the second inverter.
The Hybrid inverter then has the information it needs to calculate the load correctly and if there are any export limits set the hybrid will throttle itself to reduce it’s output to ensure the G98/G99 DNO limit cannot be exceeded.

@ADJ - as long as the CT2 from the H1G2 is connected to the live feed of S2500, it will work fine and will use any excess solar that is being exported (from either inverter) to charge it’s batteries.

@aaron as above connect the second CT to the F series and set an export limits on the H1 G2 to your 5kw limit - the hybrid will measure the absolute export being generated by both inverters and will use as much as possible to charge it’s batteries and it will not allow the export power to exceed 5kW by throttling it’s own PV (with only 5 panels the F series will simply output at full power).

[aaronlukemarshall]

@aaron as above connect the second CT to the F series and set an export limits on the H1 G2 to your 5kw limit - the hybrid will measure the absolute export being generated by both inverters and will use as much as possible to charge it’s batteries and it will not allow the export power to exceed 5kW by throttling it’s own PV (with only 5 panels the F series will simply output at full power).

Dave, thank you that is exactly what I needed to know! I wish I had space and infrastructure to support another H1 and additional batts to parallel but sadly I do not so limited in what I can fit.