Depending on your geographical location and the specific orientation and exposure of your residence or business, the amount of usable sunlight varies. Local weather patterns, influenced by factors like topography, trees, and ponds, further contribute to differences even within small regions. Consequently, two solar systems identical in construction and operation, but separated by a short distance, may exhibit varied energy outputs over time. In this blog post, I elaborate on the weather conditions impacting solar panels. This knowledge can provide a valuable foundation for crucial decisions, such as selecting panel locations and estimating the relative potential for energy generation.
Today’s weather is a short-term occurrence, whereas climate encapsulates an extended overview of weather patterns. For instance, Los Angeles might experience cold and rainy weather today (the current weather), but its overall climate is warm and temperate. Proficient solar designers analyze specific climate characteristics to optimize system efficiency. Climate encompasses factors like temperature, precipitation, and wind speed.
Here’s a look at how climate can affect your solar system:
Sunlight
The annual sunlight received is influenced by the prevailing climate. The Figure’s map illustrates the average daily sunshine hours across the United States. Unsurprisingly, the Southwest experiences the highest daily sunshine, given the region’s elevated position of the sun in the southern states, leading to longer days. However, modern solar panels can still generate some power even in diffuse light conditions.
Snowfall
It would help if you positioned your panels strategically to prevent them from being covered by thick layers of snow. Different areas on your roof will accumulate varying amounts of snow, with some parts experiencing shallow buildups compared to others. Additionally, certain sections of your roof may be warmer than others due to their proximity to heaters, exhausts, chimneys, and similar features.
Cloud cover
In regions with frequent cloud cover, solar energy remains accessible, albeit in a diffused form. Consequently, the orientation of collector panels becomes less crucial, as sunlight arrives from various angles rather than solely from directly overhead.
Smog
Air pollution and smog can reduce the amount of sunlight reaching you. If you reside in an area with significant air pollution, anticipate decreased system output for an extended duration.
Air density
In mountainous regions, solar exposure is more favorable compared to areas near sea level because the thinner air leads to less sunlight scattering. To gauge air clarity, a rough estimate can be made by observing the blueness of the sky on clear days. Air with higher density scatters more red light, resulting in a sky that appears less blue and more white.
Temperature
For PV systems (excluding solar water heaters), semiconductors perform better and yield higher output at lower temperatures. On cold, clear days, the system can generate more power than on sunny days.
Frequent fog
If you reside in a region with morning fog and mist, like the San Francisco Bay Area, where the mist typically clears up by noon, it’s advisable to position your solar panels towards the west. This adjustment optimizes sunlight capture throughout the day.
Dust and Pollution
Dust and air pollution can accumulate on the surface of solar panels, reducing their efficiency. Regular cleaning may be necessary in areas with high dust levels or air pollution.
Thunderstorms and Lightning
While solar panels themselves are not usually affected by lightning, the electrical components in the solar power system, such as inverters, may be susceptible. Proper surge protection and grounding are essential to mitigate lightning-related risks.
Hail
Hailstorms pose a potential threat to solar panels as they can cause physical damage. However, most solar panels are designed and tested to withstand hail of a certain size and velocity. Additionally, installations in areas prone to hail may use protective measures such as hail guards.
Wind
If you experience significant wind, it’s crucial to carefully choose the location for your solar equipment for a couple of reasons. Strong winds can potentially damage equipment by ripping it off its mounts, leading to costly repairs and posing safety risks. In windy climates, it’s essential to opt for heavy-duty mounting equipment with specific wind speed specifications to prevent mishaps, considering the potential expenses involved.
The wind is an efficient coolant, particularly affecting surfaces. If you have a swimming pool, an effective strategy is to incorporate landscaping that interrupts the wind flow, preventing excessive cooling of the pool water. Although solar water heating panels can efficiently warm the water, it’s prudent to address wind cooling before investing in expensive solar panels. Adding a few bushes and trees is not only more cost-effective but also enhances the aesthetics, contributing to a more environmentally friendly solution.
You can obtain generalized information and maps about the nation’s solar resources from the following:
The National Renewable Energy Laboratory: Located in Golden, Colorado, the NREL (www.nrel.gov) has a solar resources section on its Web site; follow the prompts to obtain a data log for your city, or a nearby large city. You can get an estimate of the BTU’s/square meter/day you can expect.
National Climatic Data Center: The NCDC (www.ncdc.noaa.gov), in Asheville, North Carolina, claims to have the world’s largest archive of climate data.