Page 12 - North American Clean Energy March April 2018 Issue

solar power
Large Array Solar Panel Cleaning
by Tom Fredericks
What is the best way to clean large solar panel arrays? What are the main concerns? Whether it’s a large commercial community solar garden or utility-grade solar farm, following basic guidelines can increase system output and reduce panel damage.
Prior to cleaning, you should practice the following standard operating procedures:
1. Inspect the entire solar array system to detect loose or broken wires, damaged panels, or improperly functioning apparatus. Make necessary repairs or modi cations for electrical safety.
2. Trim or remove any vegetation that may interfere with the system’s operation.
3. Schedule panel cleaning early in the day, or at night when it is cool. is minimizes thermal stress on photovoltaic cells and protective glass, which could damage the panels. Cold water can microfracture hot panels. Also, a hot panel can evaporate water too quickly before it has dissolved and lifted contaminants.
Once the array is inspected according to system guidelines, and any adjustments to meet code or specs are done, it's time to clean the panels. What do you need in order to clean them?
Spray systems are one of a variety of equipment available on the market for cleaning solar panels. Automated spray systems, much like irrigation systems, are mounted on or near panels to regularly remove dirt. Small manual systems are available with handheld or back- mounted pack devices that spray water onto panels - O&M personnel then use brushes to scrub the panels prior to a nal rinse. Manual systems are useful in remote locations, or where larger machines
or vehicles can’t navigate tightly clustered rows of an array. Large, automated truck-mounted brush systems and tanker truck operations are generally used on utility grade and larger solar systems. ese often employ an assortment of hoses that are connected to the tanker truck reservoir, as well as the support personnel needed to scrub down panels to remove heavier grime.
For years, the industry has recommended using water with this equipment. Unfortunately, plain water just isn’t an e ective cleaner.
Many solar panel manufacturers have claimed that you don’t need to clean panels, or, if cleaning is absolutely necessary, to just use water (more speci cally, deionized
water to reduce mineral deposits
and spotting). However, large-
scale solar farms that have been
in operation for a few years
tend to collect a layer of dirt
on their panels; this prevents
them from operating at their
maximum output, which can
cause problems for the owners.
Facilities located in dry climates,
or near agricultural elds, coastal
areas, volcanos, airports, bird
ight paths, or industrial areas
have almost immediate output loss due to contaminant accumulation on the panels. Many arrays require more frequent cleaning simply due to their location, and many of the contaminants do not easily rinse o with water alone. What is the best option to e ectively clean o bird droppings, jet fuel residue, plant matter, dust, sand, and other contaminants?
Cleaning tough contaminants o panels with water additives is relatively easy. e real challenge is cleaning
safely, with a product that does not degrade panel lms or the aluminum support rails. Untested products may be e ective at cleaning, but can also shorten equipment life. Proven compatibility is paramount. Specialty solar panel cleaners are commercially available. Quality panel manufacturers will have tested cleaning products for compatibility, and are an excellent source for recommendations.
Environmental concerns and worker safety must also be addressed. Cleaning e ectiveness is a key parameter, too, as this optimizes power output, saves time and labor, and helps cut water usage—
an important consideration in many locations. e goal is to nd an approved, low-toxicity, biodegradable product that enhances the cleaning e ectiveness of deionized or plain water.
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MARCH•APRIL2018 /// www.nacleanenergy.com