Solar + storage systems fall into two buckets; AC coupled and DC coupled. In DC coupled system current flows from the module strings to a hybrid inverter or charge controller then to the batteries for charging. When power from the batteries is needed the hybrid inverter or battery-based. Most existing PV system are tied into the main service panel of the building. In some instances the point of interconnection is on a subpanel or a load. If the retrofitted AC coupled storage system is to be operational in a grid backup mode, it is important to ensure the PV inverter and. For information on the tax incentives available to storage systems see our previous article HERE. Relevant to the discussion of a.