mb2155

We are an independent solar company installing a battery retrofit on an existing PV system. The PV system was installed by a different company a few years back. They are a sunpower dealer and we are not. The existing system includes two Sunpower (SMA) inverters: SPR3000M and SPR 6000M. We are installing one new SMA S.B. 5.0 inverter with an SMA ABU and an LG CHEM RESU10H battery meant to be compatible with SMA. The first issue we have is to get the older sunpower inverters to communicate with the new SMA unit/LG battery. The second issue we have is that apparently, when the grid goes down and the battery shifts to back-up mode and the SBS loses contact with the PV system, effectively shutting down the PV as a power source for loads and recharging. We've reached out to Sunpower and SMA and both have given us very little help. Our thought is we can't be the first installer to have come across this issue. Is there anyone else that has experienced one or both of these issues and what did you do to resolve it? We would appreciate any insight!