How often do you look around your house and realize everything is a dusty mess.
You clean, wipe, and feather dust everything, but keeping everything tidy is a never-ending battle.
Well, take solace that you’re not alone. Solar farms around the world deal with the same problem with varying results.
Efficiency Killers
The average solar panel has an efficiency rate above 20%, though some prototypes can perform better.
But no matter how efficient your panels are, dirt, grime, and other schmutz are a constant threat. It might not seem like it at first glance, but solar panels are constantly picking up debris called soiling. If not taken care of, those particles can cause headaches for utilities, communities, and companies.
Luckily, soiling doesn’t have to be an energy-generation killer. With some planning, proactive work, and emerging panel cleaning technology, it’s possible to easily maintain efficiency.
What Causes Dirty Solar Panels?
As with anything left outside, dust, dirt, pollen, and debris collect on panels over time.
When dirt, dust, and other particles fall onto solar panels, they obscure the cells, leading to lower efficiency. Unfortunately, this is a common problem for many solar installations, especially those in sunny, desert areas.
Dirty panels may not seem concerning, but even a little dust and debris can hurt production. According to the National Renewable Energy Laboratory, soiling accounts for as much as 7% of annual energy lost in the United States. Unfortunately, in even dustier areas like the Middle East, losses can be as much as half.
Although lost energy is an issue, let’s face it: money can be an even larger motivator. MIT experts suggest even a 1% reduction in power from a 150 MW solar project could cause $200,000 in lost revenue annually. As panels take on more soiling, losses can quickly mount, resulting in lower ROIs.
Of course, soiling does more than impair solar power generation – it can be a headache. In many cases, a good rainstorm can wash away most dust, dirt, and other messes, but that’s if there’s regular rain. In areas where rain is rare, moisture can combine with dirt and grime to create a much harder-to-remove filth.
Sometimes, it may make sense for workers to use a water jet to clean solar panels. This process uses pure water to wash away soiling – any impurities can leave water spots and deposits. Another option for solar sites is dry brushing. Brushing is generally less effective than water and may potentially scratch or damage panels.
Not all Soiling is Dirt
It might not cause the same issues as a thick layer of dust on a solar panel, but snow poses its own production risks.
When snow lands on solar panels, it’s harder for sunlight to reach cells, limiting power generation. Beyond reducing power output, heavy snow can damage panels, racking systems, and sensitive tracking components. Workers must then replace expensive equipment, leading to further lost revenue.
Unlike dirt and grime, snow is easier to deal with on a solar site. Workers can quickly remove snow with a soft bristle or foam brush, leaf blower, de-icing product, or heating system. Panels could also naturally clear themselves as snow and ice slide off the tilted panels.
Melting snow and ice offers another benefit for solar sites, as the water may remove soiling.
Powering Down: How Soiling Impacts Production
When dust, bird droppings, dirt, snow, and other debris block solar panels, it can start a chain reaction impacting short- and long-term activity.
But what types of problems can we expect, and when can we expect them? The answer isn’t always clear, but it depends on location, water resources, and cost.
Reduced Power Generation
We’ve covered this a little bit already, but when dust builds up on solar cells, it prevents them from collecting solar energy.
Needless to say, a solar panel not collecting solar energy is a problem. Over time, more dust and grime build up on the panels, causing drastic production decreases. Even worse, soiling can cement onto the panels as dirt combines with resting liquids like dew or condensation.
Soiling does more than impact initial energy output. Less generated power means less revenue, which hurts the bottom line and the project’s lifetime return on investment (ROI).
Higher Maintenance Costs
Dirty panels are more than a productivity killer – they can run up maintenance costs, too.
If rain and melting snow can’t clean the panels naturally, crews might have to drive to the site and clean them. Unfortunately, cleaning solar panels isn’t as easy as hooking up a garden hose and getting to work.
NOTE: Never allow crews to clean panels using a pressure washer. High-pressure water can damage sensitive solar cells and panel seals, even from several feet away.
Utility-scale solar systems can cover hundreds of acres, requiring the services of a professional cleaning company. Depending on how they choose to clean, the company might need to bring in pure water – regular water can leave deposits on the panels. Cleaning crews also need specific cleaning tools to prevent scratches and other damage that could impact energy production.
Another option could be to invest in a self-cleaning system. Although these systems increase upfront costs, they maximize efficiency over the installation’s lifespan.
Shorter Panel Lifespans
How often do we hear about the importance of changing our car’s oil to avoid catastrophic engine issues?
The same “ounce of prevention” advice our uncles gave us years ago holds the same value when applied to solar systems. When soiling goes untreated, it puts the solar energy system at risk.
Without regular cleaning, dirt and debris raises the operating temperature of the solar panel system, resulting in damage. If damage occurs, crews may need to repair or replace panels to regain lost efficiency.
Worse yet, muck and grime could damage other parts and pieces in the solar system, including tracking components. These sensitive components are complex – anything preventing their movement will immediately impact performance and eventually cause them to break.
Preventing Damage
Despite the potential problems associated with soiling, keeping up with cleaning is sometimes surprisingly simple.
Whether allowing nature to lend a hand or investing in top-notch tech, keeping panels clean isn’t always a battle.
Let the Rain Help
Sometimes, the easiest way to handle a dirty solar panel is to let nature take its course.
Rain, wind, and snow do a good job of keeping solar panels clean, especially between scheduled cleanings. Depending on the panel’s angle and the environment, rain and snow might be enough to wash away dust, dirt, and other debris. However, flat panels may have difficulty self-cleaning because they lack tilt.
In rainy or snowy regions, the weather can be an excellent way to maintain panel efficiency with little effort. During dry spells, dust and grime build up on the panels, but one or two rainstorms can quickly improve efficiency to near its maximum.
Keep an Eye on Systems
Problems are much easier to address early on than when left to grow.
Monitoring systems attached to solar systems can detect power generation decreases using sensors, output metrics, or other tracking. Larger sites mean more sensors, especially on farms where conditions vary from one area to the next.
Constant monitoring allows crews to investigate problems quickly and determine if they need to take action.
Maintain a Regular Schedule
Proper maintenance helps get the most out of every component throughout its lifespan.
Just like changing a car’s oil regularly, set up a cleaning schedule for the solar site and follow it. Crews can clean panels in several ways but most commonly use water or soft brushes.
Using pure water is the safest method for cleaning solar panels, but costly if it needs to be delivered by truck. Soft brushes or blower systems are a cheaper option but tend to be less effective. They also may risk scratching or damaging the thin film solar panels if done improperly.
Beyond simple cleaning methods available today are developing technologies capable of cleaning solar panel surfaces without touching them. One solution uses electrostatic repulsion to magnetically remove dust from the panel’s surface, safely cleaning it without water.
Join the Robot Revolution
As our lives become more autonomous, robots and algorithms have taken on more of our daily work.
Autonomous cleaning systems mounted onto the solar system can wipe dust from panels without humans. The process is successful in the Middle East, where sand and dust constantly threaten energy production.
Solar companies have no shortage of automated cleaning systems, with dozens on the market today. Many operate on solar power, cleaning rows of panels without water.
Keeping Up with a Constant Problem
We can’t realistically protect solar panels from every bit of dust and debris. Luckily, we have plenty of tools to help us mitigate damage.
It starts with finding optimal locations away from construction, agriculture, and trees. Later, it means investing in regular cleaning, using either water, brushing, or an automated system. Monitoring systems also play a role in reducing the threat of poor performance and lost productivity.
The solar industry is booming, not only in the U.S. but around the world. As technology improves, other innovative solutions will soon come to market, keeping our panels clean and our future bright.
