Ask a Solar Eningeer - Backup Systems (Part 1)

When we are out at events or meeting with customers, we get a lot of questions — the move to solar is no small affair, after all. One of the things a lot of people have questions about is the type of back-up they might need for their solar power system. I recently interviewed one of our lead installation engineers and asked him about several of the most common questions about solar backup, and what follows is the insight he shared with me.

Types of Backup

There are 3 types of backups that can be used on cloudy days and at night, when a solar system does not produce enough electricity to meet user needs. One is battery storage, where a battery provides users with supplemental electricity. Another is generator backup, where users get extra electricity from a generator. And the third is a purely grid-tied power system, where users get the added electricity from their utility provider. In this post, we’ll focus on the battery storage system.

Battery Storage: Supporting Uninterrupted Service

Solar energy systems with battery storage are being used by businesses and residences all over the world to power a wide range of building equipment, lighting, appliances, computers, or communications equipment. In general, these systems are best for situations where backup power must be instantly available without interruption (for example, to power computers). They are also good for remote applications in which utility power is not available and a generator is not desirable.

Batteries are an additional expense however, require maintenance, only last 5-10 years, decrease system efficiency, and result in a more complicated system. If you have access to grid power, you can take advantage of Net Metering (where available) to simply sell your excess power back to the utility during the day and draw utility power at night - at 100% efficiency. Most solar customers opt for a grid-tied system and purchase a standby generator with a properly installed manual transfer switch, avoiding the additional expenses related to batteries, and having backup power available for as long as they have fuel.

Check back next time, when we’ll continue this discussion with an overview of generator-based solar backup systems.

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