How to add batteries & more PV

[nowty]

The DNO has allowed you option 1 via the G99 fast track process.

Options 2 and 3 fall foul of,

The total aggregate capacity of the Power Generating Modules that are Electricity Storage devices do not exceed 16 A per phase and the total aggregate capacity of the Power Generating Modules that are not Electricity Storage devices do not exceed 16 A per phase.

The awkwardness is the hybrid inverter for option 2 being both an energy storage device and a non energy storage device. So in options 2 and 3 you exceed an aggregate capacity of 16 A per phase in the Power Generating Modules that are not Electricity Storage devices.

Of course what goes on the form and what eventually gets installed might be slightly different. The DNO might even OK a hybrid inverter by you ticking the boxes on the form.

I don't think a hybrid would easily charge from the existing array as they are generally DC coupled devices and some with an ability to charge from the grid but that is usually a timed affair for off peak import.

[Joeboy]

Getting too complicated for my wee brain. I'm away in the pool.

[Countrypaul]

The DNO has allowed you option 1 via the G99 fast track process.

Options 2 and 3 fall foul of,

The total aggregate capacity of the Power Generating Modules that are Electricity Storage devices do not exceed 16 A per phase and the total aggregate capacity of the Power Generating Modules that are not Electricity Storage devices do not exceed 16 A per phase.

The awkwardness is the hybrid inverter for option 2 being both an energy storage device and a non energy storage device. So in options 2 and 3 you exceed an aggregate capacity of 16 A per phase in the Power Generating Modules that are not Electricity Storage devices.

Of course what goes on the form and what eventually gets installed might be slightly different. The DNO might even OK a hybrid inverter by you ticking the boxes on the form.

I don't think a hybrid would easily charge from the existing array as they are generally DC coupled devices and some with an ability to charge from the grid but that is usually a timed affair for off peak import.

Doesn't The total aggregate capacity of the Power Generating Modules that are Electricity Storage devices do not exceed 16 A per phase apply to the hybrid inverter and the total aggregate capacity of the Power Generating Modules that are not Electricity Storage devices do not exceed 16 A per phase. apply to the FITS system, or am I reading that wrongly?

[pudding]

I don't think a hybrid would easily charge from the existing array as they are generally DC coupled devices and some with an ability to charge from the grid but that is usually a timed affair for off peak import.

That's what I was originally thinking with the hybrid inverters. Obviously it can sense and charge from it own DC connected solar array, but it would need CT clamps or some sensor to tell it when to charge from the AC connection when the other solar array is generating. Like you say, if it can only charge during set times for cheap overnight rates, and not when it detects export from the other solar array, then it's a non-started. Im trying to find a manual for that hybrid to see if it gets installed with a CT clamp to detect export. I suspect not unfortunately.

[nowty]

The DNO has allowed you option 1 via the G99 fast track process.

Options 2 and 3 fall foul of,

The total aggregate capacity of the Power Generating Modules that are Electricity Storage devices do not exceed 16 A per phase and the total aggregate capacity of the Power Generating Modules that are not Electricity Storage devices do not exceed 16 A per phase.

The awkwardness is the hybrid inverter for option 2 being both an energy storage device and a non energy storage device. So in options 2 and 3 you exceed an aggregate capacity of 16 A per phase in the Power Generating Modules that are not Electricity Storage devices.

Of course what goes on the form and what eventually gets installed might be slightly different. The DNO might even OK a hybrid inverter by you ticking the boxes on the form.

I don't think a hybrid would easily charge from the existing array as they are generally DC coupled devices and some with an ability to charge from the grid but that is usually a timed affair for off peak import.

Doesn't The total aggregate capacity of the Power Generating Modules that are Electricity Storage devices do not exceed 16 A per phase apply to the hybrid inverter and the total aggregate capacity of the Power Generating Modules that are not Electricity Storage devices do not exceed 16 A per phase. apply to the FITS system, or am I reading that wrongly?

It would apply to the hybrid and the original FIT system added together.

[nowty]

Interestingly on the ENA compliant database, the devices we are talking about are either classed as a "Generating Unit" or an "Energy Storage Device".

https://www.ena-eng.org/gen-ttr/

And I cannot find any hybrid types of devices under the class of "Energy Storage Device".

[Stinsy]

Most hybrid inverters use a CT attached to the meter tails to measure current-flow in/out of the house. So if the main array is producing 2kW, the new array 1kW, and the house was using 500W then without any storage there'd be 1500W outflowing to the grid. However the hybrid inverter would target zero flowing out to the grid and would charge the batteries by 1500W irrelevant of which array is actually generating the power.

[pudding]

Excellent, I hope you're right Stinsy and Nowty not quite (sorry!), as that would make things simpler and easier, just need to check/confirm/arrange how it would work with the DNO if possible. Again it seems illogical if it cant be installed, as if the output of that hybrid inverter is 3.6kW, then it shouldn't matter what batteries or solar PV is connected to it, as it cant output more than that 13A.

[Stinsy]

All inverters have an option to limit outflow. You just need to chose an inverter that is "G100 compliant" meaning that the method of limiting outflow complies with UK regulations and it cannot "accidentally" start exporting at full whack.

DNOs are extremely conservative in this respect.

[Joeboy]

Most hybrid inverters use a CT attached to the meter tails to measure current-flow in/out of the house. So if the main array is producing 2kW, the new array 1kW, and the house was using 500W then without any storage there'd be 1500W outflowing to the grid. However the hybrid inverter would target zero flowing out to the grid and would charge the batteries by 1500W irrelevant of which array is actually generating the power.

This was my understanding too but as I'm 4,000miles from my system didn't want to say. Personally and it is personal I would be trying to drill down into that zero output/max discharge rate for a hybrid inverter while remaining compliant. My one regret is that discharge rate is limited to under 4kW on our hybrid, hence the personal. Also to be clear my knowledge is limited.