Inquiry Regarding Solar System Optimisation Timebased Logic

[scholar2k3]

Dear All,

I hope this message finds you well. I am getting in touch to seek professional advice on optimising my solar system setup. Below are the specifications of my current solar configuration:

• Solax 7.5 G4 Single Phase Inverter
• AIKO Panels: 12 panels in each string
• Solax 12kWh Battery

The 2-string inverter operates at 600V for each string, with a total power capacity of 11000W, accounting for oversizing given the inverter's rating of 7.5kW. Each string consists of 12 PV panels, each panel generating 450W with a short-circuit current of 40.30V. Tigo optimisers are installed on each panel to monitor individual performance throughout the day.

I have identified an opportunity to enhance the system's energy generation by utilising additional flat roof space to accommodate eight more panels. The plan is to integrate four panels into each string during specific periods of the day when solar energy generation is suboptimal. However, it is crucial to automatically disconnect these additional panels from each string when the voltage approaches the 600V limit.

In considering an effective solution for this automation process, I have contemplated the use of a PLC/DPDT relay system. However, I am uncertain about its feasibility and whether there might be pre-existing switching systems designed for this purpose, eliminating the need for an additional inverter.

I would greatly appreciate your professional guidance on the most suitable method to automate the integration and disconnection of the additional panels into/from each string, ensuring optimal performance while adhering to voltage limits.

Thank you in advance for your expertise and valuable insights.

Best regards,

Scholar2k3

 

[zanydroid]

Can you just add the new roof plane in parallel, with string voltage as close as possible to original? (You can also use TIGOs to bridge a 25% voltage difference between strings)

Can you buy another string inverter or use microinverters?

Otherwise You need to find relays that can switch DC under load, and it is not passively safe if the PLC breaks. Why bother with that?