Request for Technical Assistance for Modifying a Solar PV Installation

[RenEngAlg]

I am reaching out to you concerning a solar photovoltaic (PV) installation for which certain modifications are being considered.

The installation, consists of the following components:

• A 37 kWc PV array;
• An STP 50-40 inverter;
• Three Sunny Island 8.0H in a three-phase on-grid configuration, Three phase single cluster
• An Energy Meter and a Data Manager M;
• A Hoppecke OPzV 2V/2093 Ah battery bank (24 batteries connected in series).

The system currently operates with the following functions:

• Battery charging: Current and charging power: 190A / 11.2 kW;
• Excess energy production exported to the client's electrical grid, with an average export power of 20 kW;
• Nighttime lighting supply via AC coupling with the conventional grid: Discharge current and power: 180A / 8.2 kW.

The planned modification aims to:

1. Enable the battery system to function in the absence of an electrical grid (off-grid operation);
2. Ensure that the full capacity of the PV array is utilized during daylight hours (battery charging + excess energy production).

To implement these changes, we seek your expertise to:

1. Identify any necessary modifications to the existing system, including additional equipment;
2. Ensure that the system is configured in a safe and optimized manner post-modification.

 

[Daddy Tanuki]

this is way above anything anybody here has even considered... except maybe Tim

 

[wpns]

A Hoppecke OPzV 2V/2093 Ah battery bank (24 batteries connected in series).

Not a lot of ideas, as @Daddy Tanuki said this is way outside the DIY space, but this has me confused. Is it a 48V battery made up of twenty-four 2V (lead acid AGM?) 2093AH cells in series to make a 48V 100KWHR battery? Like literally 4 tons of batteries? How old are they, and how are they currently performing? Just keeping up with their self-discharge is going to use more power than most folks _have_ in their DIY systems. Replacing them with LFP, for instance, is a whole nother rathole.

Nighttime lighting supply via AC coupling with the conventional grid: Discharge current and power: 180A / 8.2 kW.

How does this currently work? How does the battery power get back into the grid?

It's not clear if any of your inverters have battery capability, and balancing grid-tie with AC-coupled in a grid-down scenario can turn into a real nightmare. How willing are you to you to re-imagine the entire system, and are the current systems 'paid off', or how much Capex do you have available for a rebuild?

I mean, I'd be thinking about a parallel, LFP-based system for critical loads, but 'critical' is up to you to decide...

 

[HarryN]

If I understand it correctly, the system works because the grid is supplying the necessary signal ( from being a regulated sine wave ) for it to operate.

So one part of this project is to emulate this sine wave "into" the system" so that the solar will turn on.

The two most obvious methods to create this sine wave is either with a generator ( 3 phase ) or I "think" that the victron quatro can do this - but double check.