Solar Panel Cleaning Systems and their Pros and Cons

Solar Panel Cleaning System Framework

The following post is dedicated to solar panel cleaning systems for the commercial, industrial and utility-scale solar panel cleaning segment. While productivity rates are a very important KPI to define your solar panel cleaning system, we recommend considering other variables as well. Below you will find our framework for defining the best solar panel cleaning system for your portfolio of assets that need cleaning.

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Compatibility (Machine to solar installation)

Solar installations are very diverse and that is their nature. It is fundamental that you choose solar panel cleaning machinery/robotics that is compatible with the solar installations you have to clean. For example, you cannot use a tractor/brush system on an agrivoltaic installation that has crops on the ground. To make a good decision, it is important to understand the solar installation types and the machinery available. If you would like to learn more, you can enroll in our Solar panel & PV Surface cleaning school.

The Economic Value of Solar Panel Cleaning and the Opportunity

Solar panel cleaning is done primarily for economic reasons. Solar farms lose power output and hence revenue. What are the challenges we face in the Solar O&M Industry?

• Quantifying the revenue loss due to soiling
• Quantifying the ideal cleaning frequency and schedule
• Quantify the value add from solar panel cleaning
• Defining the solar panel cleaning equipment that allows for maximum efficiency for the existing PV design
• Altering the PV design to allow for
  • Efficiency
  • Operator Safety
• Identification of key difficulties in cleaning the solar installation
• Opportunity identification

Case Study = 50 MW at $45/MWh

Cleaning frequency if ofter determined by visual inspection but to accomplish an economic impact, it is necessary to work with solutions like our PV soiling monitor and software.

The Opportunity

If managed properly, solar panel cleaning does bring significant economic value. However solar panel cleaning goes hand in hand with the opportunity to apply PV anti-reflective coatings. For more information, please feel free to schedule a meeting here. https://calendly.com/soilar-tech/ In general, PV anti-reflective coatings increase performance 2-4% however knowing when this should be done is the key to accomplishing this economic opportunity. Below you can see that just 2 applications of PV anti-reflective coatings on a 50 MW site create $1,431,820 gains throughout the solar assets lifetime or an ROI of 294% in 7 years or approximately 42% per year. Since these coatings should be applied immediately after cleaning, it is a service offering that can and should be provided by a solar panel cleaning company. If you are interested in learning more about adding solar maintenance service, please contact us at Soilar Technologies. Below you can see the added value of both services on a 50 MW installation.

Solar Panel Cleaning Machinery

Solar Panel Cleaning Systems

There are many ways to clean solar panels but the general dos and don’ts include

• Don’t use a pressure washer
• Don’t use lots of water (it is expensive and the property owner will not forgive you)

• Do consider automation as it lowers the cost of cleaning significantly and increases your productivity and quality
• Understand that there are 2 main segments. 1) Commercial & Industrial Solar Panel Cleaning Systems 2) Utility-Scale Solar Panel Cleaning Systems.

Commercial & Industrial Solar panel cleaning systems

Commercial and Industrial Solar panel cleaning systems are challenging because they rarely have water and energy sources next to the solar panels. They can be dangerous to clean since they may be on rooftops, carports, or off the ground. Each installation is very unique since solar panel installers do not consider cleaning when they design the layout. Soilar Technologies offers this support to PV developers and designers.

The main systems include

Semi-Automation

Within semi-automation, you have solar panel cleaning systems

• Solar Panel Cleaning Robot – The robot is driven by an operator via remote control. The robot travels in xy-axis coordinates and is very similar to driving a remote control toy car. This system requires a high upfront cost but productivity levels improve by 4x. There are several xy semi-automated robots on the market but not all brands are the same and the quality of the manufacturer and post-sale service is important.
  • Pros – Productivity rates improve by 4x, Less exposure to employee lawsuits, it safer than cleaning manually, less water consumption, Facilitates scaling of your business. Payback happens within the first month.
  • Cons – Requires an investment of USD $20,000 – USD $50,000, Operators must be trained, the robots can be heavy and may require 2 to 3 operators. Inclination levels may be an issue.

• Lift and Shift Solar panel cleaning machine that is moved and allocated by an operator. This system also works nicely but usually requires “Custom-made solar panel cleaning robots”.
  • Pros – If inclination levels are high this robot will work, easy to use, and Payback happens within the 6 months
  • Cons – Time to delivery, since these robots are custom, you will have to wait 3 months to get them.

Manual Solar Panel Cleaning Systems

• Cleaning manually with a water-fed pole. While this system “works” for just about any installation, it is expensive in terms of labor rates and liabilities associated.
  • Pros – cheap labor can be used, easy to start a business with this method
  • Cons – Lots of people means lots of liability. Accident levels will be higher with this cleaning system. Water consumption rates are much higher with this system.

Utility Scale Solar Panel Cleaning Systems

• Tractor Brush System – This solution requires a higher upfront cost since you need a tractor, hydraulic arm, and smart rotating brush with proximity sensors however it is the most productive solution on the market.
  • Pros – The cheapest way to clean a utility-scale installation, Great payback, and ROI
  • Cons – Cannot be used on all installations, may not be ideal for very desertic areas such as the Sahara or Atacama desert

• Powered Lift and Shift – This solar panel cleaning system is great for utility-scale installations where a tractor cannot be used or the ground is pure sand like in the Sahara or Atacama desert. With this solution, the operators fix the robot to several arrays and simultaneously move them down the array. The robots can do dry and wet cleaning and are extremely productive.
  • Pros – This system works on just about every utility-scale installation, Payback compared to manually cleaning is extremely high, CAPEX values are reasonable any ROI usually happens with the first cleaning
  • Cons – More expensive than the Lift and Shift system, requires more operators than the Tractor Brush system

Fixed Slider with Docking Station – 100% Dry cleaning

Dry Solar Panel Cleaning Robotics

• – – This system is abuzz these days and conceptually it is very simple. We have one robot per row/array that is fixed and solar-powered. The robot moves back and forth daily and no human intervention is needed. While this system is being implemented the CAPEX values are extremely high and the performance loss due to soiling “the cost of being dirty” on the solar panels has yet to prove that the ROI is ideal.
  • Pros – Human intervention is only required for technical repair. Performance loss due to solar panel soiling is virtually zero. Great for areas that are VERY remote and with extremely high soiling levels.
  • Cons – CAPEX values are VERY high and performance loss due to soiling has to average over 3% for this system to be justified. The financials still do not prove that this system is economically beneficial. These solutions only work in extremely arid regions such as the Atacama and Sahara desert where humidity levels are virtually non-existent since they only do dry cleaning. These solutions do not work well where there is humidity.

Solar Panel Cleaning Automation is a very young industry. When choosing your system we recommend you work with consultants to find the best solution for your company or installation. Key takeaways

• Study the system cost not just the cost of the machinery.
• Calculate your CAPEX & OPEX for each system to determine the best solution from a financial perspective.
• Water is expensive, consider it in your analysis. Different robots have different consumption levels.
• Robots have different productivity levels, consider this in your analysis.
• Wear and Tear are extremely important – There are lots of cheap robots on the market that high very high wear and tear costs. Consider this factor in your analysis.
• Inclination levels are a factor you must know. Not all robots have great inclination levels.
• PV Soiling Levels are key. You have to compare the cost of being dirty to the cost of each solar panel cleaning system to see with the system is ideal. Invest in soiling monitoring such as the solutions.
• Work with solar panel cleaning engineers to find the best solution.

Clean solar panels for the best yields - how and why to clean the solar panels: Photovoltaics continue to enjoy great popularity in Germany, especially in industry. Alongside wind power, solar energy is one of the greatest hopes of the energy transition, accounting for 23.2% of electricity generation from renewable energies. However, the great potential of the technology is also accompanied by everyday questions: How can solar panels from large systems, for example on the roof, be cleaned efficiently and safely? What photovoltaic cleaning equipment is available? We explain the do's and don'ts of automated solar cleaning with robots.

How often and with what should a solar panels be cleaned?

In order to function optimally, it makes sense for operators of solar power systems to clean their PV modules regularly. This is because soiling such as bird droppings, grease and rust dust have a negative impact on the performance of the modules. According to the Fraunhofer Institute, soiling can significantly reduce the maximum output of a PV system. This not only reduces the yield of self-used solar energy, but also reduces the potential feed-in to the electricity grid and the corresponding remuneration. How often a system actually needs to be cleaned using conventional cleaning aids or modern PV cleaning robots depends in particular on its location and the precipitation there. Professional cleaning of solar installations is recommended at least once a year, especially in agricultural areas.

Which cleaning methods are useful for solar cleaning in industry?

Cleaning robots are an integral part of modern facility cleaning operations. The same applies to the cleaning of large PV systems. Here, the solar cleaning robots score particularly well thanks to their high efficiency and environmental compatibility - because the high rotation of the brushes ensures an optimum cleaning effect without harmful and environmentally damaging chemicals. If you also clean with osmosis water instead of conventional water, the positive effect is maximized.

5 tips - Solar panel cleaning : how to do it right

To ensure that regular cleaning of the solar panels with the PV cleaning robot is efficient and safe, there are a few important points to bear in mind:

1. safety first: Getting the solar cleaning robot safely onto the roof

Safety is the top priority when it comes to using robots to clean PV modules on the roof. Roofs in particular have individual requirements.

As a general rule, cleaning should always be carried out by a professional using climbing aids or, ideally, ABS fall protection grids. The great advantage of solar cleaning robots - compared to manual cleaning of PV systems, e.g. with telescopic poles - is obvious: cleaning staff do not have to enter the roof at all. Once the robot has been placed on the roof and secured with ropes, it does its job safely and reliably. Experienced cleaners should always carry out a visual inspection of the parts before commissioning and switch off the solar installation for the duration of cleaning.

Link to Trinabot

Good to know: The hyCLEANER solar cleaning robots are equipped with fall protection sensors . This allows the robot to recognize the end of the solar surface at an early stage and can be steered in the opposite direction for optimum cleaning of the solar panels.

Before use on the roof, a function check of the cleaning robot including edge detection, as currently only offered by hyCLEANER, is important: Watch our video here.

2. adjust the cleaning behavior of the surface and clean the solar panels correctly

Depending on how dirty an area is and how high the angle of inclination is, the cleaning behavior with the machine must be adapted. This includes roping up the robot, but it is also important to use the right driving pads. For example, it is advisable to use rubber driving pads if the area is heavily soiled with ammonia (e.g. in cowsheds).

Good to know: The hyCLEANER accessories include three different driving pads - leather, rubber or neoprene - for different applications and surface requirements. They can be easily exchanged using the Velcro fastener.

Important: Also clean the brushes of the machine and the driving pads after cleaning - this can easily be done with running water. The following applies: Never clean the machine or PV system with a high-pressure cleaner!

3. pre-cleaning: Note the grip and angle of inclination before cleaning the solar panels

Similar to snow groomers, the solar cleaning robots are driven by two chain-driven undercarriages, which give them the necessary grip on the slippery, sometimes steep surface. Similar to the rubber compound for cars in winter and summer, the hyCLEANER cleaning robot has different types of tracks that can be easily changed using Velcro, depending on the area of application:

• one especially for dry cleaning, e.g. in desert regions
• one for normal soiling (depending on the machine model with a climbing ability of up to 25°)
• one that is specially developed for cleaning very dirty surfaces, such as cowsheds

Correct handling of the driving pads is essential to ensure the necessary grip. Pre-cleaning one or two panels before placing the robot on them is therefore always recommended (see also next point). For the best possible grip, it is also advisable to ensure that the hose is guided from above. This prevents the load from pulling downwards and making contact with the surface more difficult.

Also important: Before cleaning, the slope of the roof should be checked using a measuring device and the surface conditions correctly assessed. Depending on the model and surface condition of the area to be cleaned, the hyCLEANER cleaning robots are suitable for surfaces with slopes of up to 25° (47%).

Tip: For stubborn stains, you should soak the roof beforehand or ideally clean it after a long period of rain.

4. observe water pressure and water quantity

For maximum cleaning effect, pre-cleaning and main cleaning with water is recommended. Osmosis water is particularly suitable for both processes. The filtered water, from which salts, minerals and other impurities are removed in advance, is very gentle to clean - and yet highly effective.

To ensure gentle and successful cleaning, it is essential to use a sufficient amount of water. This is because the less water is used, the more likely it is that dirt will rub against the collector surface. This means that there is no flushing effect to loosen the dirt, meaning that the same areas have to be cleaned several times.

Solar robots work with low pressure. This means they don't need that much water pressure. Two to four bar is sufficient - this corresponds to the amount that comes out of the tap. Nevertheless, there are pressure losses associated with the hose diameter and working at height. As a rule of thumb, you lose 1 bar of water pressure for every 10 meters of height.

The diameter of the hose is just as important as the correct water pressure. It must be large enough to pump enough water into the robot. With the solarROBOT series from hyCLEANER, it is important to use supply hoses with an internal diameter of at least 10 mm.

Important: Under no circumstances should high-pressure cleaners be used for cleaning, as the high water pressure also damages the sensitive surface.

Cleaning PV modules with water: Did you know that robots use much less water than conventional high-pressure cleaners? At approx. 0.5 liters/m², that's up to 10 times less water per square meter.

5. take proper care of the battery

To ensure the longevity of the cleaning robot, you should recharge the battery from time to time, especially during the cleaning-free winter months. Similar to an e-bike, so-called "battery jogging" is important to ensure that the battery maintains its performance. What does that mean? It should be used regularly.

Robots revolutionize the professional cleaning of solar panels

The use of solar panels on roofs is not only gaining momentum in the agricultural sector. However, in order for the systems to function optimally and generate good yields, operators must maintain and clean them regularly - an attractive opportunity for professional cleaning companies and solar panel operators who take over the cleaning of their PV system themselves. Cleaning robots that clean solar panels safely and efficiently have proven themselves in use. Anyone who pays attention to the above points and pays attention to safety, cleaning basics such as water pressure, water quantity and machine care, as well as the roof condition and battery check, is ready for a lucrative solar season.

Frequently asked questions about solar panel cleaning

Cleaning solar panels with glass cleaner: does it make sense?

Chemical cleaning agents are harmful to the environment and health, cause costs and are comparable to other cleaning methods in terms of efficiency. Cleaning solar panels with glass cleaner is therefore not recommended.

Osmosis purification works at least as efficiently. Using special filter technology, a PV system can be cleaned with treated tap water. This makes it harmless to the environment and health compared to chemical agents and very cost-effective to operate.

Can you clean photovoltaics with rainwater?

Yes, rainwater can indeed be an effective and environmentally friendly way to clean solar panels during the year, especially if it falls in sufficient quantity and intensity to naturally wash away dust and other debris. In many cases, rain can reduce or delay the need for manual cleaning, especially in regions with frequent rainfall. While rainwater can be helpful for cleaning solar panels, it is important to inspect the solar panels regularly and perform a mechanical cleaning at least once a year.

If you want to learn more, please visit our website Solar Module Cleaning Robot.