The IRS in a private letter ruling has allowed the FTC for adding battery storage to an existing grid-tied PV system, so long as the batteries only store electricity generated by the PV system and not from the grid. The 30% credit continues through 2019, and it could be a big boost to longer duration PV systems and increase the opportunity for self reliance. Also reducing grid reliance could be a big boost in areas where grid-tied net meter rate for buy-back is less than the homeowner rate for grid power. Solar Batteries