There are environmental benefits to making the switch from a fossil fuel generator. Instead of buying, and storing fossil fuels, your grid-tied battery could run more quietly, and from cleaner fuel sources.
The benefits of a standby generator include that they have high output, can be connected to your natural gas or propane and are on standby. The drawbacks of a standby fossil-fuel generator include that they have a higher lifetime cost, require professional installation with fuel, involve permitting, require maintenance and are not portable.
The benefits of a battery include that they are silent, emit no fuel, enable you to store and use your solar PV energy, are on standby, and have incentives available through Energy Storage Solutions. The drawbacks of a battery include that they have a high upfront cost, require professional installation, interconnection, and permitting.
Additionally, commercial and industrial customers with existing fossil fuel generators will be permitted to request capacity rights in order to monetize storage assets into ISO-NE market programs (if they take existing fossil fuel generators offline).