The purpose of batteries is to store the extra energy for later use when there is no sunlight. It is not compulsory to store excess solar power in a battery. You can use solar power without batteries if you want. The batteries can be advantageous in the case of cloudy days, and night-time.
Grid-Tied Solar power without batteries.
When the sun is bright, and the grid-tied solar system generates more power. And the excess solar power is transferred to the utility grid. The utility grid payoff the consumer for the extra energy generation. During the night-time or during a cloudy day the consumer is draining energy from the utility grid. Such type of solar power system does not need any backup batteries as the grid is working as a large battery.
With a grid-tied solar power system, you can also use backup batteries. This is not needed but it could backup during grid damage or gird shutdown.
Hybrid Solar Power with and without batteries
In a hybrid solar power system, you may rely on solar power and battery backup. This may be the case if you want to minimize the use of grid power and prefer solar power day and night. For example, if you are living near to a utility grid that is not reliable or very expensive, or frequently disastrous. Or you are living in an area with no net metering available for consumers because a grid-tied system needs a net metering system for your grid. In these cases, you may need hybrid solar power with battery backup.
Off-grid Solar Power with Batteries
If you are living in a remote area where have no grid availability and you need power during nighttime. So backup batteries are required. In cases like agricultural pump may still work without batteries if there the pumps are only used during the daytime. But if you are using solar power for lighting your house during the night and want other appliances to run around the clock. Then you need backup batteries for your solar power system.
- Off-grid solar power needs batteries if you are using it day and night.
- A hybrid system can add value to the system if you add batteries. This can work without batteries.
- Grid-tied solar systems work without batteries and no backup is required but the grid should be able to handle net metering.