Maintaining Off-Grid Power Systems Through an Ice Storm

Over the past 12 years of off-grid living, we've encountered some significant weather extremes during our travels across the continent. Believe it or not, we're writing this blog during an ice storm that has knocked out grid power all over the High Country of North Carolina, so our timing could not be more poignant! While our system has been fine, we've needed to rely on just about every trick we have to stay powered up in the cold.

This winter, North America has already seen some pretty weird weather; snow on the ground for days in New Orleans, Louisiana, icey blizzards across the mid-Atlantic states. As severe storms become stronger and more difficult to predict, the obvious questions arise: Will the solar panels keep up, will the batteries get too cold, what if the system goes down? With just a few strategies and the right equipment, you can be prepared for whatever Mother Nature throws at you.

Winter's Impact on Solar Systems

Solar powered systems don't really love the winter – shorter days, low sun angle, precipitation and of course the cold winter weather can impact your off-grid production. Let's see how various solar components are affected by the cold…

• Batteries: All deep-cycle batteries, regardless of battery chemistry, will start to lose performance as the temperatures plummet. While most will continue to deliver power well below freezing, it's never a good idea to charge any battery at those temperatures – doing so can significantly damage the internal cells and reduce the lifespan of the battery. Many Lithium Iron Phosphate batteries have a low-temperature cut off built-into the battery management system (BMS) that prevents any charge when below freezing. This built-in safety factor means that you won't have to worry about any potential damage, or keeping one eye on the thermometer.

• Solar Panels: Snow and ice can quite obviously reduce or knock out solar production altogether when panels are covered. Also, colder temperatures increase the solar panel output voltage. While this increase can help compensate for other winter time power losses, it can also cause problems for the charge controller. Depending upon how the solar array is configured, series vs. parallel, the solar array output may overwhelm the charge controller input parameters.

• Charge Controllers: It's important that your charge controller (i.e.,the brain of the system) can also operate in very cold conditions. If the “brain” freezes in very cold weather, it may not properly regulate the charging current sent to non-self heating batteries, thus causing internal battery damage. Conversely, in the case of self-heating batteries, a charge controller that functions at very low temperatures is necessary to keep that required 4A of current flowing in order for self-heating to begin and charging to commence.

• Grid Reliability: If your system is partially tied into the grid, your ability to power your own needs will depend on whether your system has any power storage (batteries) or if you simply have solar panels to off-set your energy usage. It's important to know the difference between on-grid and off-grid solar because not every home solar installation has a battery bank backup for when the grid goes down.

• Equipment Durability: Cold weather is hard on technology – ice, snow and sub-freezing conditions will make demands on your equipment just as it does on the larger grid power systems. Most high quality solar components are built with weather extremes in mind so that you can keep producing and using power even when the temperatures are well below freezing.

The key to finding ways to make the most of extreme winter weather is to understand how to mitigate and minimize the specific challenges that winter places upon our equipment.

Here are a few ways to be even more prepared…

Winter Off-Grid Power System Planning, Maintenance, & Cold Weather Solutions

Battery Capacity – Will you have enough power in the winter? It's important to size your system with the lowest solar gain time of year in mind. How do you know how much battery capacity you need? Use our comprehensive Solar System Sizing Calculator (a free downloadable worksheet which includes a guide to calculate your insolation) to do a simple, yet thorough energy audit.

Protecting Batteries from Freezing – Insulation methods vary from low to high tech. Simply insulating your batteries from the cold with a battery blanket or heated battery wrap will help. Lead acid batteries should not be charged when their core temperature drops below their stated specifications, which is a major limiting factor of this older technology. Conversely, many Lithium Iron Phosphate batteries (LiFePO4) now offer a self-heating function that allows for both low-temperature cut off and warming the batteries to facilitate charging in freezing temperatures. When the battery detects a charging source (Solar, DC to DC, or AC to DC) the LiFePO4 will turn on a small heating element that gently warms the battery up to a more efficient charging temperature. Typically, the heater will turn on when the battery falls below 41°F and shut off when back up to 51°F. The power consumption and heating rate depends upon the specific battery as well as the internal temperature at which the heating begins.

Maximizing Solar Input with MPPT Solar Charge Controller – Another way to protect batteries from the cold, and improve the efficiency of your whole solar powered system is through the right MPPT solar charge controller. The Rover Lite 60A Charge Controller with MPPT has an excellent operating temperature range (-31°F to 113°F) and low-temperature protection for LiFePO4 batteries. It is compatible with multiple system voltages (12V - 48V), and can handle a maximum solar input voltage of 150V making it one of the most flexible solar charge controllers with MPPT for the off-grid DIYer. The wide range of input voltage means that this charge controller can easily handle any colder temperature voltage increases. And its ultra-low power consumption, (0.18W for 12V systems) is nearly 85% lower than similar models, making it a perfect choice for just about any system. To learn more about PWM vs. MPPT Solar Charge Controllers, check out this article.

Clearing Solar Panels- Ice, snow, and even leaves can quickly build up on your solar panel array, reducing their efficiency significantly. As an interesting side note, while the glass and metal surfaces of our camper and truck were covered with ½” of ice, our 100W Flexible Solar Panels remained nearly ice free during one of the biggest ice storms we've ever experienced, due to the insulating properties of their ETFE plastic.

If it's snow that you are dealing with, it's pretty easy to just sweep the snow off any solar panels with a foam broom, and let the sun do the rest of the work. Therefore, it's important to think about being able to access your array location in winter so that snow and ice removal can be accommodated, i.e. the ideal location for maximum power might not be the best location for easy and safe snow removal. Maybe the best location is some compromise between the two?

Because most RV solar array installations are mounted flat, for mobility, clearance and safety while driving, snow and ice accumulation can be the bane of winter off-grid RV efficiency. You may also consider installing tilt brackets for best solar gain while you are stationary, which will allow snow and ice to melt even faster.

How to Remove Snow and Ice from Solar Panels:

• Safety first! Never go up on a roof impacted with snow or ice unless you can reach them from a safe and stable platform. Note: We can easily clear our roof-top solar panels on our RV by using the tailgate on our truck as a platform.
• Clear snow and ice with a foam headed snow broom.
• Spray water on the panels until the snow and ice are washed away, then dry with a rubber squeegee. Note: Do NOT use boiling water as the temperature differential on the glass could make it crack.
• Blow off snow with a leaf blower.
• Use a plastic shovel to remove snow.
• Consider installing a heating device. If this seems to be a problem winter after winter, you might want to consider installing a roof-heating device to contend with the ice and snow.
• For more information, check out this article.

Is There a Better Solar Panel for Snow & Ice?

The shading effect of collected snow and ice can reduce solar panel output all together. Renogy has recently developed a more shade tolerant solar panel, the ShadowFlux Solar Panel (available in 120W or 200W), which will continue to produce power when other panels stop producing power altogether. These panels are not only lighter, thinner, and smaller than traditional panels of equivalent power, but also offer the industry's highest efficiency rating.

Plan for Power Outages

Living with solar power is like balancing a banking account, you can really only spend what you can bring in. If you're looking for ways to reduce your installation budget, consider building a system that can power just the essential items during the lowest solar gain season. Alternatively, if you're living in an RV and want to maximize power production, take advantage of your mobility and head south in the winter!

Develop a “Plan B” Strategy

Sometimes even the best plans and implemented systems can come up against their limitations. Having a backup plan in place is always key! Using a gas generator, or large solar generator, can be a great asset for your off-grid project. Renogy's Lycan 5000 Power Boxcombines the large capacity 48V battery bank, charge controller, and 3000W inverter charger into one compact, weather resistant package. See our video review.

Thriving during winter's worst weather just takes just a little bit of planning and practice. These strategies can help make the most of the least pleasant weather we might experience during the year. Consider how your battery bank chemistry will be impacted, how to clear your solar panels of snow and ice, and use a cold tolerant solar charge controller, like the Rover Lite 60A Charge Controller with MPPT, to limit the threat of freezing temperatures to your battery bank and improve your system's efficiency. We sure don't have to like the weather, but we can always be better prepared for it!

Shari Galiardi & David Hutchison have turned their higher education backgrounds, desire for life-long learning, and thirst for adventure travel into writing, photography, video production, and public speaking tours from coast to coast. Known to their friends as simply S hari & Hutch, you can learn more about their full-time, solar powered adventures on their website at freedominacan.com. Or, follow them on Facebook, Instagram, and YouTube as “Freedom in a Can.”Save even more on most Renogy products using our promo code CANLIFE – even on sale items!