| On-Grid | Off-Grid | |
|---|---|---|
| Fits | Homes and facilities with a grid that want a lower bill | Sites with no grid, or where extending it is costly |
| Batteries | Not needed | Essential for night and dusty days |
| During a grid outage | Stops, to protect the grid and those working on it | Keeps running within battery and panel capacity |
| Sizing basis | Daytime load and self consumption | The worst production month |
| Surplus | Follows net billing at a value below the purchase price | Lost once batteries are full |
| Financial comparison | Against grid tariffs and the fixed charge | Against diesel or the cost of extending the grid |
Before On-Grid
- Connection follows the provider's requirements, net billing and contract capacity limits.
- Oversizing beyond daytime load weakens returns, because surplus earns less.
- The fixed charge stays, so do not accept a zero bill promise.
Before Off-Grid
- List the daily load in detail: device, power, hours.
- AC units and motors need more starting power than running load.
- Lithium and gel differ in depth of discharge and life, so compare lifetime cost.