For members of the UKSN, a reliable solar power station is crucial when camping, preparing for emergencies, or taking part in outdoor adventures. Solar power is a clean, renewable energy source, but in cold weather, managing the voltage output is key to avoiding damage to your power station.
Many solar power stations, such as the EcoFlow Delta 2, can handle a maximum voltage of about 60V. When temperatures drop, the voltage output from solar panels increases, which can push your system closer to this limit. This guide will walk you through how cold temperatures impact voltage, how to calculate safe limits, and practical ways to protect your solar power station from overvoltage damage.
Understanding How Cold Weather Affects Solar Power
Solar panels work by converting sunlight into electrical energy. As temperatures drop, solar panels produce higher voltages. This is due to a reduction in the resistance within the photovoltaic cells, which increases voltage output. For every degree Celsius below 25°C, voltage typically rises by about 0.4%.
While this may sound beneficial, as more voltage equals more power, it can also lead to overvoltage. This becomes a significant concern when the temperature drops far below freezing. Without proper precautions, you risk damaging your solar power station if it exceeds its maximum voltage input.
Why You Need to Be Careful with the Voltage Limit
Many portable solar power stations used by UKSN members are designed to handle a maximum voltage input of around 60V. Going beyond this can lead to:
Battery damage: Excessive voltage can overcharge and overheat the battery, shortening its lifespan.
Charge controller failure: The charge controller, which manages the power flow from the panels to the batteries, can become overloaded or even break if the voltage exceeds its capacity.
Inverter damage: Inverters convert DC power from the solar panels to usable AC power. Exceeding their voltage limit could result in system-wide failure.
Cold Weather and Voltage Calculation
To prevent your solar setup from experiencing overvoltage, you need to calculate how much voltage your solar panels will produce in cold weather and ensure it stays under the safe 60V threshold. Here’s a step-by-step process to help you stay within safe operating limits:
Identify Your Solar Panel's Open Circuit Voltage (Voc): Every solar panel has an open circuit voltage (Voc) at standard test conditions (usually 25°C). This value can be found in the specifications sheet that comes with your solar panel.
Calculate Voltage Increase in Cold Weather: Voltage increases by roughly 0.4% for every degree Celsius below 25°C. For example, if the Voc of your panel is 45V at 25°C and the temperature is expected to drop to 0°C, you can calculate the increase:
Temperature difference: 25°C - 0°C = 25°C
Voltage increase per degree: 0.4% of 45V = 0.18V
Total increase: 25°C × 0.18V = 4.5V
So, the new Voc at 0°C would be 45V + 4.5V = 49.5V.
Compare to the 60V Maximum Input of Your Power Station: If your power station’s max input is 60V and your new Voc is 49.5V, you're within the safe range. However, you should always leave a margin for safety, so aim to keep your operating voltage at least 10-15% below the maximum input.
Account for Colder Temperatures: If temperatures are expected to drop further, for example, to -10°C, calculate accordingly:
Temperature difference: 25°C - (-10°C) = 35°C
Voltage increase per degree: 0.4% of 45V = 0.18V
Total increase: 35°C × 0.18V = 6.3V
Now, the Voc would be 45V + 6.3V = 51.3V. At -10°C, you’re still under the 60V limit, but the closer you get, the more cautious you should be.
Real-World Example for UKSN Members
Imagine you're heading out for a winter camping trip in the Scottish Highlands, where the temperature can drop as low as -15°C. Your solar panel has an open circuit voltage (Voc) of 48V at 25°C, and your power station has a maximum input voltage of 60V. Here’s how to calculate whether you're safe:
Temperature difference: 25°C - (-15°C) = 40°C
Voltage increase per degree: 0.4% of 48V = 0.192V
Total increase: 40°C × 0.192V = 7.68V
New Voc: 48V + 7.68V = 55.68V
At -15°C, your new Voc would be 55.68V, which is still within the safe range for your 60V power station. However, with only 4.32V of margin left, you’ll need to monitor the temperature closely and ensure your solar setup doesn't face extreme cold that could push the voltage higher.
What Input Voltage can EcoFlow Products Handle?
To save you having to hunt out the input voltage of your EcoFlow power station we have compiled a list below.
River 2: 11-30V, 8A, 110W Max
River 2 Max: 11-50V 13A, 220W Max
River 2 Pro: 11-50V 13A, 220W Max
Delta 2: 11-60V, 15A, 500W Max
Delta 2 Max: 11-60V 15A, 500W per port (1000w Max)
Delta Pro: 11-150V, 15A, 1600W Max
PowerStream: 55V, 400w per port (800w Max)
Please note: The figure quoted for watts and amps are the maximum the power station can utilise. Feel free to over panel all you like improving performance in low light, and poor weather situations. The only hard limit you have is the voltage. Do not exceed this!
Protecting Your Solar Power Station from Overvoltage
Here are some practical ways to ensure your solar power station stays protected from overvoltage in cold weather:
Leave a Safety Margin Below 60V: While 60V is the maximum input, it's wise to keep your operating voltage lower than this. A 10-15% buffer is a good rule of thumb. For a 60V system, aim for a maximum operating voltage of 51-54V to ensure safety.
Monitor the Weather: Cold snaps can bring temperatures lower than expected. Be aware of local weather conditions during the winter months, and adjust your solar setup as necessary.
Use Fewer Panels in Extreme Cold: If you know the voltage will rise significantly due to extreme cold, consider disconnecting some panels. This will keep the overall voltage lower and reduce the risk of overloading your system.
Additional Tips for Optimising Solar Power in Cold Weather
Maintain Clean Panels: Snow and ice can block sunlight, reducing energy production. Clear your panels regularly to ensure maximum exposure to sunlight, even during the short daylight hours of winter.
Angle Your Panels for Winter Sun: In winter, the sun sits lower in the sky. Adjust the angle of your solar panels to better capture sunlight during the shorter days.
Use Energy Efficient Devices: In cold weather, you may need to conserve as much power as possible. Use energy-efficient appliances and LED lights to reduce the demand on your solar power station.
Conclusion
For UKSN members, understanding how to manage voltage in cold weather is essential to protecting solar power stations from overvoltage. By calculating voltage increases, leaving a safety margin below the 60V maximum input, and using the right equipment, you can ensure your solar setup remains reliable, even in freezing temperatures.
Whether you're on a bushcraft expedition or preparing for your next UKSN Charter camp, following these guidelines will help keep your power station running smoothly and extend the lifespan of your solar equipment. Stay prepared, stay powered, and stay safe with these practical tips for cold-weather solar power.
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Want to Learn More About EcoFlow or Portable Energy Solutions?
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