How Do Off-Grid Solar Power Systems Work in Winter?


Residents of Arizona, Southern California, and other sunny regions have no problem committing to a solar system. The year-round sunshine and clear skies make solar power an easy choice. But what if you live in an area with harsh winters? 

Contrary to popular belief, solar power systems can perform well over winter. They just require preparation and maintenance. 

Frigid temperatures can adversely affect battery banks, charge controllers, and other components. Care is necessary to house these devices at suitable temperatures. But with the proper preparation, you can optimize their energy production. 

How Does Temperature Affect Solar Panels?

Solar panels may perform better and produce more energy in colder temperatures. The reason is that heat can impact energy output by as much as 10-25%. Cold temperatures reduce the likelihood of the panels overheating, thus protecting their efficiency.

However, in areas with changing seasons, it’s not just the temperature that’s a concern in areas with changing seasons. The amount of peak sun hours is a significant factor in solar energy generation. 

How Do Solar Panels Perform in the Winter vs. Summer?

Everyone knows solar panels work well in the summer because there are more sun hours. Winter brings shorter days and fewer sun hours because the Earth’s tilt on its axis makes it face away from the sun. Fewer sun hours means less energy production. However, there are ways to maximize performance in the winter to get the best results.

With proper preparation, photovoltaic (PV) panels can still harvest adequate solar power. Keep in mind the sun travels lower in the sky during winter. To receive more direct sunlight, you should tilt solar panels to face the southern sky. The exact angle will depend on your location and time of year. 

Taking care of your batteries will also help your solar system perform well. Some important aspects of solar battery care are: 

  • Store your batteries above freezing temperatures. Insulate them if needed.
  • Monitor your battery charge levels to ensure that you don’t over-discharge them. 
  • Perform a battery equalization charge if required. 

These solar battery care tips are detailed below. 

What Happens if Solar Panels Freeze?

If solar panels are completely blocked by snow or ice accumulation, they will not be able to produce power. Light snow will generally melt or slide off your panels if installed at an angle. You may need to brush the panels off after a heavy snowstorm to allow the sun to reach them again. 

How to Prepare Your Off-Grid Solar System for Winter

When winter is coming, you need to prep your system. You’ll need to take action both inside and outside the home. 

Angle Your Panels

The sun travels lower across the sky during the winter. This results in shorter days and less direct sunlight. You should change the angle of your panels to follow the winter sun pattern. 

Some mounting brackets allow for a relatively simple adjustment of the solar panel angle. Other mounts are fixed and won’t allow for this adjustment. 

Reduce Energy Usage

No matter how much preparation you do, your solar panels will likely produce less power during the winter. You will have to be extra wary of your energy usage. Possible ways to reduce your electricity consumption include: 

  • Turn lights off whenever you leave a room
  • Supplement heating with wood or natural gas
  • Allow the sun to come in through the windows
  • Use space heaters, as opposed to full-home central heating
  • Install weatherstripping around your windows and doors

Insulate the Battery

Cold temperatures slow down the chemical reactions that occur within a battery. This solution is acceptable for long-term storage, as this lessens the rate at which a battery self-discharges. 

However, cold can also slow the battery’s charging and discharging rates. The effect is reduced efficiency of your solar system. 

If your off-grid solar system still utilizes lead-acid batteries, it’s best to store them in ventilated, sheltered spaces such as a garage or shed. The hydrogen gas produced by flooded lead-acid batteries is unsafe for indoor spaces. Lead-acid batteries generate heat, so a battery box with padding should keep them at optimum temperatures even when outside. 

If you use lithium-ion or lithium-ion phosphate (LFP) batteries, you can safely store them inside your home. The LFP batteries found in many EcoFlow products can operate effectively at temperatures between -4° to 122° Fahrenheit (-20° to 50° Celsius).  

Monitor Battery Discharge Levels

The winter has fewer monthly sun hours than the summer. Reduced sun hours mean your batteries will not recharge as quickly. If you continue to use your batteries at the same rate, you may deplete your battery levels more quickly.

LFP batteries — such as those featured in the EcoFlow Power Kits — can safely be discharged to around 80%. You risk damaging your batteries if you deplete them all the way. 

Keep an eye on your battery levels throughout the winter to prevent damage. Most EcoFlow products—like the EcoFlow DELTA Pro Solar Generator—let you monitor and control battery performance through the EcoFlow smartphone app.  

Equalize Battery Bank 

Some lead-acid batteries benefit from an equalization charge, where you overcharge a battery after it has cycled through a full charge. Equalization removes excess sulfate that builds up and balances the voltage of the battery cells.

Many charge controllers or stand-alone, wall-plug chargers will have an auto-equalization feature. This mechanism increases the voltage from a standard 12V to around 16V and maintains this voltage for a few hours. You can set many charge controllers to perform this function every month.

How to Maintain Your Off-grid Solar System During Winter

Each solar system component has its own maintenance requirements to perform well over the winter. 

Solar Panels

  • Panel Tilt: Angle the panels towards the sun’s path in the sky. A steep angle of around 60° usually works best in the northern hemisphere. The best tilt can change depending on your exact location.
  • Clearing Snow: Brush off your panels after heavy snow. Prolonged snow coverage will block sunlight from hitting your panels. 

Solar Charger Controllers

  • Performance Monitoring: Make sure that sensors and other components are working correctly. Older systems may require routine maintenance if the charge controller features a temperature gauge. Inaccurate temperature readings could result in your batteries charging at improper voltages. 
  • Charge Controller: A high-quality solar charge controller — preferably MPPT (maximum power point tracker) — will monitor the ambient temperature and adjust the voltage delivered to your batteries. 

Battery Banks

  • Insulation: Exposure to freezing temperatures can have adverse effects on your batteries. 
  • Winterizing: If you’re not using your off-grid space during the colder months, you may want to “winterize” the system. Charge your batteries to 100% and then disconnect them if you leave them unused for a prolonged period. 
  • BMS: Use batteries that include a battery management system (BMS). It’s essential for lithium-ion, LFP, and other types of batteries. A BMS will prevent thermal runaway and other issues.


  • Temperature Regulation: Inverters work best at room temperature (or close to it). They can handle some temperature fluctuations but should not drop to below freezing. Install your inverter and related components indoors to prevent any issues. 

Solar Generators

  • Pre-Charge: Make sure to keep your solar generators topped up with power. Don’t just leave it sitting in a closet! The generator may have slowly lost stored energy over the year. Keeping adequate charge levels provides backup for the power outages that come with intense snowstorms
  • Solar Generators:  These all-in-one solutions include batteries, charge controllers, solar panel(s), and more in one plug-and-play package. The above battery tips also apply to generators, such as keeping them within their suggested temperature range and monitoring their discharge levels. 

The Time To Go Solar Is Now

There has never been a better time to go solar. Technology has advanced dramatically in recent years, allowing costs to come down. And with customizable, integrated setups like the EcoFlow Smart Home Ecosystem, the average homeowner can even install the components themselves.

If you plan on hiring a professional, installation costs can be cheaper in the winter. Solar professionals receive less work in the winter, so they may be willing to install your system at a reduced rate. 

Go off-grid — and stay warm — this winter with clean, renewable solar energy.

EcoFlow is a portable power and renewable energy solutions company. Since its founding in 2017, EcoFlow has provided peace-of-mind power to customers in over 85 markets through its DELTA and RIVER product lines of portable power stations and eco-friendly accessories.

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