One Minnesota homeowner hoping to start a cheap solar panel project and add backup power later sparked a debate about what it takes to cut utility bills and keep the lights on during an outage.

Here's what to know

The discussion began in a Reddit thread posted to the site's r/SolarDIY forum after the homeowner said a utility rate change had driven costs sharply higher, writing, "Our bills have doubled."

The original poster said that they wanted to use a sunny detached garage to bring down a household load of about 900 kilowatt-hours per month, with expansion plans deferred. As the OP put it in a comment, "I would be OK with a $20 electric bill and the cost of solar."

Commenters zeroed in on the biggest complication, added blackout protection.

Whether the system could safely provide backup power depended on the buried line between the garage and house, the inverter setup, and the transfer-switch arrangement, one user said. "You need batteries to have power when the grid goes down. Solar is only part of the solution," they added.

Standard grid-tied solar systems usually shut off during outages for safety reasons, making battery backups critical for outages.

Still, one commenter pointed to a notable exception: an Enphase IQ8 configuration paired with an IQ System Controller 2 and a neutral-forming transformer. Even then, that kind of setup requires specialized equipment and careful design.

Using the homeowner's monthly consumption of 30 kilowatt-hours a day, one estimate put the minimum solar array at 8.6 kW. That commenter suggested 9-10 kW DC as a more realistic starting point since snow, weather variation, panel aging, and imperfect roof orientation should be considered.

Because the plan involved a detached garage, several roof orientations, possible future batteries, utility interconnection, and even salvaged vehicle battery packs, another commenter urged professional design help. "There are enough interacting pieces here that a mistake can get very expensive very quickly, and some mistakes could be deadly," they warned.

More background

Cutting your electric bill and building backup power are related goals, but they are not the same project. A grid-tied system may reduce monthly charges, while a battery-ready hybrid system can add resilience, albeit at a higher upfront cost.

If you're considering panels, EnergySage can help you get free solar and battery backup installation estimates and allow you to easily compare quotes.

Plus, EnergySage's solar map shows the average cost of a home solar panel system by state along with details on solar panel incentives in each state. With EnergySage's help, the average person can save up to $10,000 on a solar purchase and installation.

Where can I learn more?

If you're weighing the same trade-off between lower electric bills and backup power, these stories show how other homeowners approached it. 

• One person skipped the battery, added an EV charger, and said the solar worked fine.

• Solar owners debating off-grid upgrades say they don't even notice power outages with battery backup.

• Homeowners are racing toward bill-slashing futuristic tech that keeps lights on during outages.

Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.