Keep the existing system information together
Collect module and inverter models, the single-line diagram, connection capacity and operating records. A roof photograph is not enough. State whether the original inverter will remain, whether its warranty is active and whether export is permitted. These details affect the storage connection and control approach.
Compare coupling options in context
AC-coupled storage can often retain the PV inverter, but metering, protection and controls must work together. DC coupling requires checks of voltage ranges, interfaces and compatibility. An efficiency figure alone cannot settle the choice. Available space, shutdown time, equipment condition and expansion plans also matter.
Specify backup separately
Improving self-consumption concerns normal grid-connected operation. Supplying loads during an outage additionally requires an islanding strategy, switching, grounding and defined critical-load circuits. Whether the existing PV inverter can participate must be verified for the actual equipment and controls. Ask for separate operating boundaries for normal service and outages.
Further reading: samrepo.nlr.gov
This article supports early project discussions. Final configuration depends on site conditions.