Should I connect my solar power system to a battery backup?

No matter the size and scope of the DIY solar system you choose to install, you will need to decide at some point whether you’re going to want to store some of that power in a backup system.

To battery or not to battery — that is the question.

Most of the time, battery backup systems are associated with off-grid solar installations. But that does not mean they can’t be used with grid-tied systems that connect to your local electrical utility.

Grid-tied systems with battery backups are becoming more and more common as they help homeowners become less reliant on the utility grid. If you choose an energy storage system for your grid-tied installation, one of the biggest advantages you will experience is the ability to supply power to your home in the event of a power outage. In grid-tied systems without storage, when your portion of the energy grid loses power, your home will be without electricity. But with a backup power supply, power will continue to flow to your home from the battery backup if a power outage should occur.

Another type of grid-tied installation that makes use of battery storage is a hybrid system. Hybrid solar power systems store excess energy during daylight hours to be used at night when solar panels are not generating energy.

If you decide to go with a grid-tied system with a batter backup, you still will be able to transfer and sell surplus power back into the grid.

For off-grid systems, power storage is essential and usually part of system design.

In either type of setup, you will need to decide on the amount of storage you need. Here’s how to do that:

• Calculate your home’s daily electrical load. How many watts of power do you need for the various electrical devices and appliances in your home?
• Make sure your solar panel array is large enough to produce enough wattage for that daily load.
• Determine how many days of electricity you would like to have stored in your battery system.
• From that, figure out how many batteries you need.

Finally, you will need to purchase batteries and a battery inverter (or inverters) that allow you to supply your home with the power you will need when relying on backup power.