Homeowners looking for reliable backup power often ask us whether they can pair a generator with a home battery storage system. The short answer? Yes, you can! But how the solar, batteries, and generator integrate with each other depends on several factors, including the size and model of the battery system, whether it’s a whole-house backup or emergency loads-only design, and the size of the generator and its type of transfer switch.
At True South Solar, we install Tesla Powerwall, FranklinWH home energy storage, and Sol-Ark hybrid inverter systems, all of which can integrate with a properly sized generator. The systems are designed to automatically switch over to battery power when the utility grid shuts down. When paired with solar, the batteries will continue to recharge from the solar panels (when sun is present) without the grid. By monitoring your home or business energy usage, battery charge, and solar production from your phone or device app, it’s easy to know how much electricity you can use to maintain power indefinitely under the right conditions.
There are times when a solar + storage system alone will not be able to power a home. Homeowners can pair a generator with a solar and battery system as an emergency backup, in case the solar production can’t keep up with battery charging due to excessive power usage, too much snow or other long periods of time without sufficient sunlight. With some of our systems, the battery will charge from the solar while the generator is in use and with others the generator may be able to help charge the batteries, much like an RV.
Choosing the Right Generator
Not all generators work well with home battery systems. Our Supervising Electrician, Lance Aryeff, explains that a generator can be added as an emergency backup in case solar production can’t keep up with battery charging. Some of our systems allow the battery to charge from the solar while the generator is in use, while others may enable the generator to charge the batteries, much like an RV.
Some larger generators (usually 90 amps or greater) can produce a solid enough voltage output and steady frequency that allow the solar system to continue functioning while the generator is in use. Others may require the solar to be isolated, which can be done automatically or manually, depending on the battery and generator transfer switches.
Generator Transfer Switches: Automatic vs. Manual
The two commonly used generator transfer switches are automatic and manual:
- Automatic Transfer Switch: When the grid goes down, the batteries nearly instantly begin powering the home. If battery levels get too low, the system will automatically switch to the generator, which may take a few minutes to start and take over powering the loads. Depending on the models, the battery may be able to charge from the generator or solar while in use. Some systems will handle isolation automatically if designed with a larger generator.
- Manual Transfer Switch: A smaller generator can be integrated with a simpler manual emergency backup system. This requires manually switching between different power sources to safely isolate them, and in some cases, manually starting the generator. With this setup, solar may still recharge the batteries while the generator is in use, but the battery must be manually disconnected from the generator and grid via a switch.
When grid power returns, the battery’s automatic transfer switch will monitor for stability before switching back to normal utility grid power, allowing your batteries and solar to resume regular operation.
Which System is Right for You?
If you’re considering adding a generator to your backup power plan, Sol-Ark or FranklinWH are the best choices because they allow direct generator charging. Tesla Powerwall is still a great option, but it functions best as a primary backup, with a generator serving as a secondary power source.
With our team’s decades of battery experience and continued research, we have found what we believe to be the best tried-and-true products to meet almost any need. If you’d like to discuss the best backup power combination for your home, contact True South Solar today!
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About True South Solar Founded in 2010, True South Solar is Southern Oregon’s premier solar and storage installation company. We’re relentlessly local, offering trusted, top-tier solutions to help homeowners and businesses achieve energy independence. Our expert team is here to guide you through every step of the solar and storage journey.
Interested in learning more? Check out our Top Ten Questions to Ask Your Solar Installer PDF for more insights!