Posted on November 15, 2014 by Ryan Brown | 0 Comments
In many parts of the northern hemisphere, the leaves are falling, temperatures are dropping, and winter is just around the corner. Many people pay attention to the turning of the seasons because it means they need a new coat -- but for those who utilize solar and wind energy, it’s even more important to understand how this change affects PV and wind energy systems.
Unlike coal or natural gas power plants, which basically function the same way no matter the location, both solar and wind systems are inherently dependent on their location and the time of year. Renewable energy system designers plan for these changes, utilizing weather data, insolation maps, anemometers, and modeling software to ensure the system is reliable and efficient all year round. Often this means designing a system based on the historically least sunny and windy day of the year.
For example, near the equator, insolation is almost constant year-round, whereas polar regions have very little sun during the winter months. Because this is so site specific, renewable energy systems are most productive and cost effective when they are customized to their unique environment.
Panels capture energy from photovoltaic light -- not from the sun’s heat. In fact, heat actually reduces the efficiency of solar panels, but during colder months, their energy production can increase by up to 15%. Despite this benefit of cold weather, winter days have fewer daylight hours, so the net change of amount of energy produced will be lower than during other times of the year.
One way to make up for this loss of solar panel efficiency is to incorporate wind, creating a hybrid renewable energy system. Winters in most regions tend to bring stronger winds, which help offset the loss of production seen from PV. This same balanced system design can also be applied to differences between day and night, where solar panels produce energy from light during the day and wind turbines take advantage of nighttime winds.
Batteries often have reduced efficiency at extreme temperatures. In order to account for this loss, renewable energy system designers must assess the energy needs and the site resources. In some extreme climates, it may be advised that electronics and batteries are housed in a temperature controlled enclosure.
Snow and ice can cause added load on solar panels, so this possibility should be factored into structural design as well as energy production estimates for the winter season.
The good news? While winter weather often brings increased power outages, renewable energy systems designed for off-grid use can provide uninterrupted electricity, even when power lines go down. Microgrids, as well as backup storage, are becoming increasingly popular for the added resiliency and energy security they provide.