I'm thinking about setting up a DIY solar system with a 6KW capacity. I can handle mounting the panels and micro-inverters myself, but I'll need an electrician for connecting everything to my main or sub panel. My main panel is rated at 100 amps, but I also have some extra slots available in a sub panel located in my garage. The solar panels will be installed on the roof of the garage, which is about 40 feet away from the main panel. Can I keep my existing 100 amp panel, or will I have to upgrade it? What's the best way to determine if an upgrade is essential? I'd prefer to avoid extra costs unless the electrician needs to do significant work to integrate the solar system with the main panel.
2 Answers
Generally speaking, you might need an upgrade. If you're going with a grid-tied system in the U.S., the permitting process will check how much solar you're trying to install. With around 25 amps from your planned system, you could be exceeding 125% of your panel’s bus bar rating, which is a red flag for the electric utility. Plus, if you're in Southern California, it's likely your new meter combo will need a higher bus capacity to handle that solar output. So, unless you’ve got a brand new setup, upgrading is probably on the table.
You can technically do line side taps while staying within your 100 amp limit. This lets you get up to 100 amps of solar without upgrading, but you really need to check if your local rules require a panel upgrade for compliance. It's always best to consult with your electrician about what makes sense for your installation—some areas have specific requirements that you can't overlook!
Why not just go for the upgrade? It could save you headaches down the line.