Solar battery backup

Solar battery backup is one of the main benefits of installing a solar battery. However, not every home battery can provide backup in the event of a power outage.

Some solar batteries come with backup functionality and it can be configured to other systems. Typically, battery backup only applies to some appliances and not the entire house.

In this article we look at how solar battery backup works and help you evaluate if you need this type of storage solution for your home.

Solar battery backup during a blackout

Typically, solar batteries work by storing excess solar energy so that it can be used when the sun isn’t shining. Solar panel systems, including those with home battery storage, are designed to shut down during a blackout. This is a safety feature to protect the system from power surges.

Some storage systems are able to provide solar battery backup. When the grid goes down, the battery can provide stored electricity to the house. How much electricity it can provide depends on:

• The length of the blackout
• How much is stored in the battery
• What level of electricity is needed during the blackout

Some batteries are able to provide electricity to the entire house in a blackout, while others are designed to backup important appliances only.

Not all batteries provide backup power

Not every solar battery comes with backup capability. For batteries that don’t come with backup, a special inverter can be used to provide backup power, but this is not possible for all battery systems.

If solar battery backup is a feature that you really want, you need to be clear when dealing with your solar company.

Not all backup systems are equal

It’s important to understand that not every battery backup solution is the same. Some batteries may be able to provide more continuous power during a blackout. While other backup solutions may only last longer, but provide limited power.

What level of battery backup do you need?

If you want battery backup with your hybrid system, you need to ask yourself what level of backup is important to you. Start by asking yourself these questions:

• Do you live in a bushfire prone area?
• Does your neighbourhood regularly suffer from blackouts?
• Do the blackouts typically last for a long period of time?
• Which appliances do you need to access during blackouts?
• Is there a critical appliance that you need to keep running at all times?

Irregular blackouts

If you only experience blackouts every once in a while, you probably don’t need to get too concerned about the ins-and-outs of solar battery backup. Chances are, the grid will be back up and running within a few hours, by which time you may have used all of the stored power in your battery.

Regular and long-running blackouts

If you experience regular blackouts that last more than a couple of hours, the configuration of your backup system needs serious thought. Your battery will only last so long during a blackout, and that’s assuming it is fully charged when the blackout occurs.

Regardless of their size, many solar batteries only have a 5kW maximum power output, which means that if you are caught with all of your appliances on at once, you may overload the battery inverter causing the system to shut down.

If your battery doesn’t trip, it will only get you through so long before it is fully drained. The solution to this problem is a partial battery backup.

Partial backup: Critical loads panel

It is possible to avoid having your battery discharge too quickly by having a critical loads panel, an independent circuit that continues to run during a blackout. By putting the necessary devices on this circuit like lights, fridge, modem and a few designated power outlets, you are far more likely to keep the power on during a prolonged blackout.

A critical loads panel will add to the cost of your solar battery.

Your system may force a shutdown during a blackout

Your solar power system may be configured to shut down when a blackout occurs, to protect the battery. If the grid is down and your battery is fully charged, the excess solar has nowhere to go. To protect the battery from overloading, the system shuts down.

This means that if the blackout occurs during the day, your battery can no longer charge. Soon enough you will drain the battery. It is possible to avoid this situation with a top-of-the-range battery and inverter.

The best backup solution

If you suffer from regular and prolonged blackouts, or a particular appliance is critical for day-to-day living, you need the best available backup solution. A good solar battery backup solution will do the following:

• Have a critical loads circuit that operates during a blackout
• Allow your solar panels to continue to charge your battery during the blackout
• Backup your entire home

The critical loads circuit will keep the battery running for longer and avoid overloading the battery inverter. If the blackout occurs during the day, or extends into the next day, your solar panels can continue to charge your battery giving longer power supply.

Solar battery backup cost

Battery backup may add to the price of the solar battery. The cost of solar battery backup varies depending on the battery, the configuration of the system and the type of backup you require. Some batteries include a form of battery backup, while for others it needs to be configured.

Best to budget for between $1,500 – $3,500 extra for solar battery backup, depending on the level of backup you require.