Benn, If the client prefers the independence and thought of remaining primarily offgrid, has sufficient PV and battery for his loads, but wants to use the grid as his "generator" then HBX can really be a great solution. I'll take exception to William's comments -- with the FX you can set grid charging separately from HBX, no double conversion required. If the batteries get low because of bad weather or bad in-laws, HBX simply transfers the loads over to the grid. You can program the system to recharge with either grid or renewables. With that PV array and battery ratio, it shouldn't take long to refill the batteries purely from solar.
Grid-tie can also be a good solution as every electron the system can generate goes to good use, either powering loads or spinning the meter backwards. In addition, the batteries don't cycle so should last longer. However, your client's 9kW of array is more than two GVFX inverters can process. In addition, talk with your inspector and utility first. They might require the entire system be brought up to modern code standards before allowing interconnection. Depending upon how old the downstream wiring and components are, that might be easy, might be hard. In either case, if you have an X240 for OB Stacking it will need to come out. Anytime you have a battery based system and grid, you will need an upstream panel and a downstream panel, even if you keep the entire house on the PV system. You already have the downstream covered, but Dan's right about needing a service rated upstream panel, and you will likely need to move the Neutral-ground bond to this panel as most inspectors will require the bond to be at the first point of disconnect and point of highest potential fault current. Make sure you float all the neutrals in the existing AC Flexware as part of the retrofit. If you go with the grid-tie, the upstream panel will need to be larger than 100A to comply with 705, Dan was a little off on that. With a battery based inverter, you only need to calculate based on the grid interactive component, but still a 100A loadcenter isn't enough to allow more than ~4.8kW in selling. Best wishes with the project, whichever direction you take. Phil _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
