Adding battery backup to a solar system buys continuity for chosen loads during an outage. It does not buy free energy, and it does not protect the whole building unless the building is small or the battery is large. This page compares the two configurations honestly.
Without a battery, a grid-connected system is simpler and cheaper to configure, and it stops when the grid stops. With a battery, the configuration gains an inverter arrangement that can island the backup circuits, a battery bank sized to a chosen list, and the behaviour every backup buyer actually wants: the lights, the refrigerator and the router stay on while the street goes dark.
The cost driver is the backup list, not the battery brand. Every load added to the list adds storage. The planning discipline — essentials in, deferrable loads out — is what keeps a backup configuration proportionate.
| Question | Without backup | With backup |
|---|---|
| Outage behaviour | Stops with the grid | Carries the listed backup loads |
| Configuration | Array and grid-tied inverter | Array, backup-capable inverter and battery bank |
| Sizing basis | Daytime load profile | The backup list and the hours it must run |
| Best fit | Stable grid, no critical loads | Loads that must not stop |
Before ordering, confirm the minimum order quantity and lead time for your configuration, and ask which documents apply to the exact system you are quoted.
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