Ontario permits backup batteries, but one electrician is trying to sort out a practical issue: whether a home's existing 200-amp Generac transfer switch can be repurposed for a solar-plus-storage system.
For homeowners who already have standby equipment, the answer could affect project cost, since reusing a switch may avoid extra hardware if inspectors and code requirements allow it.
Here's what to know
The question surfaced in a Reddit post. There, the electrician said his client already has a 200A Generac automatic transfer switch installed, even though they never added a generator. The customer's solar inverter has failed, and the replacement under consideration is a battery-charging model that would sit outside the net-metering arrangement.
The OP said, "Can we use the automatic transfer switch, or will we just have to put a NEMA 30A plug outside so he can use the battery?"
They framed the issue as a code and inspection matter.
They said, "Backup batteries are now legal in Ontario Canada, however I've never actually installed them and my inspectors can't seem to answer some questions."
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More background
Ontario tradespeople still appear to be adjusting to the change. One user asked, "What do you mean now legal? Were they not before?" The response suggested that residential battery backup remains unfamiliar, even in a forum for electricians.
The OP replied, "It wasn't in the previous code book and as far as I know in my area they weren't allowing them."
If that reflects local practice, it helps explain why a house with a 200A transfer switch already mounted may still lack a simple path to battery integration.
The user who asked about it being legal followed up: "Hmm fair enough. I've worked in some old 1960s low rise buildings that had battery racks for emergency lighting DC panels, but have never seen it for new builds now that you mention it."
The comparison set older battery-based backup systems apart from the newer consumer use case of pairing batteries with rooftop solar.
What can be done?
From the post, two practical paths emerge for this Ontario project. One is to determine whether the existing 200A Generac automatic transfer switch can legally and safely work with a new battery-capable inverter. The other is the electrician's fallback option: install a NEMA 30A plug outside so the customer can use the battery another way.
In this case, the unresolved issue isn't whether the client wants storage, but whether an existing Generac component can keep the project from becoming a more expensive redesign.
They also explained why he is looking beyond older battery setups: "I did a stand-alone system years ago using golf cart batteries and a plastic truck tool box, but mice moved in, customer never maintained their batteries and it was honestly one of the most disgusting things I've ever had to disconnect."
Where can I learn more?
If you're trying to figure out whether old generator hardware still fits into a battery plan, these articles add some useful context. They explain why some homeowners are moving from standby generators to batteries and how solar-plus-storage systems perform during outages.
• Homeowners weighing Generac upgrades are also finding backup solar can offer savings that generators never deliver.
• Across U.S. neighborhoods, installers say next-gen home backup batteries are replacing loud, fuel-hungry standby equipment.
• More families are retiring gasoline units because home batteries for backup power avoid fumes, noise, and refueling.
• During outages, solar households are discovering battery-backed home power can keep essentials running without a generator.
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