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“Whatever else happens, don’t let the batteries sit at a low state of charge for long periods.”
Photo Credit: iStock
A homeowner with a 12-kilowatt-peak solar setup told the r/solar subreddit that the house has been “pretty much offgrid” since adding a battery in April, but they are now trying to figure out how to prepare the system for five darker months of weaker solar production.
At the top of their concerns was their battery’s discharge limit.
In the Reddit post, the homeowner described a 12-kilowatt-peak solar system — listed as “2x6kWp PV” — with a Sungrow SH10RT-20 inverter and an SBR256 battery that was connected in April.
They wanted to know whether leaving the discharge limit at the default 5% still made sense for five darker months.
The home has been producing enough power for months to sharply cut grid use. The poster said the system makes about 60 kilowatt-hours on a sunny summer day and about 40 kilowatt-hours in mid-October, meaning much of that electricity can be used directly or stored instead of bought from the utility.
More than one reply favored keeping a bigger reserve. 
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“I’d feel a bit more comfortable setting to 10% or even 20%,” a commenter wrote.
A second commenter went even further: “I agree. I wouldn’t let mine get that low either. I’m set at 20%.”
The homeowner is not deciding whether solar is worth it; they are trying to protect existing savings through the least productive part of the year. The poster also said they do not expect the battery to reach a full charge again until March.
If winter production falls from 40 kilowatt-hours a day to roughly 10 on an average December day, as the poster expects, every decision about battery reserve affects how much stored solar can offset paid electricity from the grid.
They also clarified in a reply that the house remains connected to the grid. 
“Yeah, I am connected to the grid,” the original poster explained. “In the inverter, I can choose to fill the battery with grid electricity to 100%, so that’s not the issue.”
That shifted the conversation from outage planning to battery care. As the original poster put it, “Outage isn’t something I’m worried about. I want to avoid deep discharges.”
Taken together, the replies leaned toward a 10% to 20% floor as a more comfortable winter setting than 5% if the goal is to avoid pushing the battery too deep.
One commenter offered a more specific warning, writing: “Whatever else happens, don’t let the batteries sit at a low state of charge for long periods, e.g. more than a day or two. They don’t like it.” 
For a grid-connected home, that can mean using the inverter’s option to top the battery up from grid power when needed. Another commenter suggested setting the reserve so the battery can still refill to 100% by the end of generation on a bright winter day.
It is as much a utility-bill strategy as a hardware one, helping a household use as much self-generated electricity as possible without draining the battery more than necessary.
Commenters suggested pvoutput.org and SunSleuth to compare winter generation with other systems and get a better sense of what kind of daily charging is realistic.
For homeowners leaning more on solar, questions about backup power, battery economics, and day-to-day savings get real fast. 
• One household said full-home battery backup made outages almost unnoticeable after a solar upgrade.
• Across the U.S., homeowners are choosing home batteries as prices plunge and bills climb.
• With only 20 states keeping net metering rules intact, home batteries look different financially.
• In Connecticut, a new bill gives home batteries a major advantage before incentive caps bite.
• In Australia, a homeowner said blackouts became invisible after a 20-kilowatt solar installation.
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© 2025 THE COOL DOWN COMPANY. All Rights Reserved. Do not sell or share my personal information. Reach us at hello@thecooldown.com.

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