Grounding multiple arrays in Grid Tie system
Hi everyone. New forum user but longtime solar user and NAWS customer. Existing system was installed by solar contractors in 1999, no longer in business. I’m in the middle of installation of a second array installation being added to the existing.
3kw system using 48 – 64w Unisolar panels (48v)
Dual 5500 w Trace inverters connected for 240v located in garage
24kw battery bank at 48v
Array location is 300ft from garage. Array grounding is at panels and Inverter system ground is tied to that ground
2.9kw on garage roof using Panasonic HIT240w (4 strings of 3)
157v at 20 amps out of combiner. Each string is properly fused at combiner.
Midnight Classic 200 controller and midnight lightning arrestor
50a breaker in Midnight bigbaby box
New controller will connect to the existing battery bank plus/minus providing additional charging source for total of 5.9kw. Actually less than that since the aging Unisolar system is < 2.5kw.
Proper grounding. Should I:
1. Ground the garage array to a separate rod at the garage and ground the new equipment to that rod only. Is there an issue with grounding potential differential with the separate grounding between the two systems with both connected to the battery bank?
2. Ground the garage array to a separate rod at the garage and ground the equipment to the existing inverter grounding block. (Note, there are no more ports on the block bigger than 10awg or maybe 8awg)
3. Ground the garage array and all new equipment to the existing grounding block in the inverter (Note, there are no more ports on the block bigger than 8/10awg) Fear of lightning strike at this point traveling through existing system with ground 300ft away but more importantly wiring issue on the block with no more large gauge ports available. I do have a lightning arrestor at combiner.
4. Option 1 (separate grounding) but connect the two grounds together through the inverter grounding block and new combiner ground block. With inverter grounding block port availability can I run multiple 10/8 awg to compensate for lack of single 6 or 4awg wire if they need to be connected.
Thanks for any enlightenment.