What is Sunlight Backup?

Sunlight backup is an Enphase feature that allows you to run your solar panels when the power goes out, even if you don't have a battery. This differs from most solar setups, which are required by law to shut down when the power goes out.

Sunlight Backup works out well for some customers, but it has limitations that make it unattractive to others. Read on to learn about equipment needed, Sunlight Backup's limitations, and Project Solar’s recommendations.

Sunlight Backup Equipment and Cost

Limitations

Recommendations

Sunlight Backup Equipment and Cost

To get Sunlight Backup, you need Enphase IQ8+ microinverters (standard with Project Solar installs), and an Enphase System Controller. 

Together, the IQ8+ inverters and the System Controller “island” your solar panels from the grid during an outage. This prevents the panels from sending power to the grid, but lets them send it to your home instead.

Sunlight Backup is not currently available through Project Solar.

Limitations

The capabilities of Sunlight Backup are limited. The system can only power about 4-8 outlets while the grid is down, and power will only be provided if the sun is shining. 

If the power goes out at night, you won't have any backup. If it goes out in the day, you will be limited to around 4-8 outlets in sunny weather.

Recommendations

Because of its limitations, Project Solar rarely recommends Sunlight Backup as a stand-alone feature. However, the same capabilities that allow the Enphase IQ8+ inverters to provide Sunlight Backup also allow them to expand the capabilities of batteries, so installing a small battery can be a better idea.

For customers who want the features of Sunlight Backup, we usually recommend an Enphase IQ battery instead. This will provide all the benefits of Sunlight Backup (you will be able to use your panels during outages), but you’ll be able to back up much more, and it won’t matter if the sun is shining.

For more detailed information on how IQ8+ inverters can work with a battery, check out this use case document from Enphase: System Use Cases for IQ8 Microinverters

You may also want to compare the Enphase battery models to Project Solar's portable battery banks, which are even more cost-effective.