Adding a battery backup/storage option to your solar PV system will greatly increase the cost and return on investment. You’ll need to consider the initial cost of the batteries and the maximum projected life (measured in "cycles" – charge and discharge). The high cost and short life of the batteries, when compared to your solar PV system may affect your decision.
If you’d like a backup power source during outages, an efficient generator will likely serve you better than a battery bank. Most of our power outages occur during winter storms when days are short and solar PV systems are producing little power to recharge a battery bank. Battery power is short lived and extremely limited. Please see PUD 3’s web page on Generator Safety for more information.