During cold snaps, particularly in winter, some customers notice their solar battery isn’t charging or discharging as expected. This can understandably cause concern, but the good news is that this behaviour is normal, built-in protection, not a fault with your system.
Here’s what’s happening, why it occurs, and the simple steps you can take to manage it.
Why batteries pause in very cold weather
Modern lithium battery systems are designed with safety and long-term performance in mind.
Most domestic solar batteries:
- Will not charge below 0°C
- May not discharge at very low temperatures (typically between -10°C and -20°C, depending on the model)
This is intentional. Charging a lithium battery when it’s too cold can cause internal damage over time, so the system automatically pauses charging until temperatures rise again.
If you have a system from manufacturers such as Sunsynk or SolaX, this protection is standard and expected behaviour.
What you can do to help your battery during cold spells
1. Use Force Charging from the grid
One of the most effective solutions is to force-charge your battery from the national grid during colder periods.
This:
- Keeps the battery active and healthy
- Helps maintain normal charge/discharge cycles
- Can slightly raise the battery temperature
Best practice
- Set 2 charging windows per day or night
- Around 2 hours per window is usually sufficient
There are step-by-step video guides available online for each battery and inverter model. A quick Google search for:
“[Battery or inverter make & model] force charge from grid”
will normally bring up the correct instructions.
2. Check the battery temperature in your monitoring app
Most systems allow you to view battery temperature directly in the monitoring app.
For charging to work:
- The battery temperature must be above 0°C
- If it’s below this, even force charging won’t activate
This is a useful first check before adjusting any settings.
3. Improve insulation (if safely possible)
Some customers choose to insulate their battery to reduce heat loss during very cold weather.
A common, low-cost option is:
- An insulated hot water cylinder jacket
- Lightly secured with bungee cords or string
- Easily removable when temperatures rise
⚠️ Important:
- The battery must already be above 0°C before fitting insulation
- Insulation won’t heat the battery, it simply helps retain warmth
4. Let the system recover naturally
If none of the above options are suitable, the safest option is simply to leave the battery alone.
Once outdoor and indoor temperatures rise:
- Charging and discharging will automatically resume
- The system will return to normal operation without intervention
Prolonged cold exposure can affect performance temporarily, but modern batteries are designed to recover.
A quick note on solar panels in winter
Cold temperatures themselves do not damage solar panels, in fact, panels are often more efficient in cool conditions.
However, panels won’t generate properly if they’re covered by:
- Snow or ice
- Dirt or debris
- Bird mess or tree sap
We recommend:
- Annual cleaning, or as needed
- Using de-ionised water or a proper solar panel cleaning solution
- Avoiding abrasive brushes or harsh chemicals
There are specialist maintenance companies available if access or roof height makes this difficult.
Reassurance from the Novus Energy team
If your battery isn’t charging during freezing conditions, it doesn’t mean anything is broken, it means your system is doing exactly what it’s designed to do.
If you’re ever unsure:
- Our team can talk you through app settings
- Help you check temperatures
- Guide you on the safest next steps
Simply fill out the form below or give us a call on 01422 768113.