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    Dirty solar panels

    I was on a rooftop working on an air conditioner and noticed that my customer's solar panels were filthy. Is this an issue? How dirty can they be and still provide acceptable performance? Should they be cleaned periodically? Is this a service i can offer? FWIW, My wife and I both did get the state PV installers certificate years ago but never needed or wanted or took a job in the PV field. But I'm on rooftops a lot. I'm comfortable up there working. Can I bring up a pole squeegie and some proper detergent and be of value?

    #2
    I know the panels are supposed to be clean-- but birds and air pollution are the enemies of solar power!

    Be careful with a choice of cleaning agents-- some panels probably have coatings that should not be abused. I know my cell phone cautions against anything with ammonia in it (like Windex).

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      #3
      Originally posted by MAC702 View Post
      I was on a rooftop working on an air conditioner and noticed that my customer's solar panels were filthy. Is this an issue? How dirty can they be and still provide acceptable performance? Should they be cleaned periodically? Is this a service i can offer? FWIW, My wife and I both did get the state PV installers certificate years ago but never needed or wanted or took a job in the PV field. But I'm on rooftops a lot. I'm comfortable up there working. Can I bring up a pole squeegie and some proper detergent and be of value?
      if you have a customer, i'd get a pail of soapy water and some window washing stuff.....
      ~New signature under construction.~
      ~~~~Please excuse the mess.~~~~

      Comment


        #4
        Originally posted by MAC702 View Post
        I was on a rooftop working on an air conditioner and noticed that my customer's solar panels were filthy. Is this an issue? How dirty can they be and still provide acceptable performance?
        Define 'acceptable'. How does 85% sound? Because that would be a very dirty solar panel. Sunlight is powerful and has a way of getting through translucent films of dirt.

        Should they be cleaned periodically?
        Define 'should' and 'periodically.' Here's what I tell my customers: 'I don't tell my customers to clean their panels because I don't think I should be telling people to take that risk going on their roof. The rain does a good enough job most years. If you have a one story house and it is easy to use a garden house to rinse off the panels in between watering your plants, that's a great strategy. If you do take the risk of getting on your roof to scrub them, don't do it too often: The more often you do it the less of a boost you get each time. Doing it once every couple years might be all that's worth it.'

        Is this a service i can offer?
        Yes but it won't make you rich. It will be by far most cost effective for large commercial arrays, and perhaps larger residential systems. The money saved by average residential customers would not be enough to pay you for driving to the house and setting up your ladder.

        And I'll just note again that the more often you clean, the more the returns diminish. The boost in production will be less if they are still pretty clean from the last time you were there. So if it's worth it to someone to pay you, say, $250 to show up once a year, it may not be worth it to them to pay you $500 to show up twice.

        Before I finished this post, I looked up your location in your profile: You're in a pretty dusty place with not much rain. So if there are places in the country where it is worth it and someone can make decent money offering a service, you might be in one of them. So worth a try perhaps. I would find some solar systems where someone is willing to cooperate with you in doing a pretty controlled survey of the production monitoring before and after cleaning, to develop some data and find if there's a good financial case to be made.

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          #5
          I would think that the company that owns the PV installation should be monitoring it and see when production falls off. They also should have a tech visit once a year to inspect and clean. No?

          -Hal

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            #6
            The questions some of you are asking me is why I'M asking. I don't know what's "acceptable" (or how it's measured or known by the PV installation) or what's "periodical."

            I should, however, clarify, that I have no intention of making this a big part of my business. But, for example, today's job was repairing the air conditioner and I could have added on cleaning the PV panels while I was there.

            I don't know the arrangements of the typical installations here. I thought many were owned by the homeowner, or leased or something like that, but I would assume the installation company gets their cut whether they are efficient or not.

            Comment


              #7
              Originally posted by hbiss View Post
              I would think that the company that owns the PV installation should be monitoring it and see when production falls off. They also should have a tech visit once a year to inspect and clean. No?

              -Hal
              Those assumptions should hold for utility scale systems. For commercial and residential owners, I think the chance that they will be diligent in monitoring diminishes with the size of the system. The majority will not be concerning themselves with squeezing the last few possible percentage points of energy production out of their system as long as they are saving about as much money as they were promised when the system was proposed. People have other things to think about. Also many proposal's production estimates are often conservative. So if someone has a monitoring portal that states they are producing 105% of estimated production, they are not going to pay someone to go clean their panels to find out if cleaning increases it to 106% vs 109%. Or at least it's not high on their to-do list.

              There is also the fact that the magnitude of production loss from soiling, especially when it is less intense, will be difficult to distinguish year to year from other factors such as weather variation and module degradation. It's not straightforward to flag some particular amount of production that 'falls off' that indicates it's time for a cleaning.

              I mean, if a company has a large enough system then yes, they should have someone monitoring it and checking it periodically as the details call for. But that would also depend on the company being well managed. Dare I point to that other thread about Tesla...

              Comment


                #8
                Originally posted by MAC702 View Post
                The questions some of you are asking me is why I'M asking. I don't know what's "acceptable" (or how it's measured or known by the PV installation) or what's "periodical."

                I should, however, clarify, that I have no intention of making this a big part of my business. But, for example, today's job was repairing the air conditioner and I could have added on cleaning the PV panels while I was there.

                I don't know the arrangements of the typical installations here. I thought many were owned by the homeowner, or leased or something like that, but I would assume the installation company gets their cut whether they are efficient or not.

                Something you should know is that those things run at voltages of 350-450VDC, typically and the conductors are free to air in the array. The MC4 connectors and PV wire are great but nothing is impervious to failure. I wouldn’t be worried with a optimizer or micro inverter system where you can prety much shut production down at the module level but on a true string system, I wouldn’t want to be working wet outside of dusk or dawn.


                I was and am considering making cleaning and maintenance a substantive part of my business but you have to understand that it takes a lot of dust to impact production. A little bit of shade from a nearby tree on just one panel for a few hrs a day will make as big if not a bigger impact.

                Comment


                  #9
                  Someone seems to think they can make money at it. Every once in a while I see a truck here in Jersey for a firm that cleans PV panels. Here's one:

                  Solar Panel Cleaning Solar Panels must be clean and free of debris so that they can produce an much energy as possible. We have the required skills, tools and equipment needed to keep your panels spotless. Don’t risk climbing up on your roof to

                  Comment


                    #10
                    Originally posted by gadfly56 View Post
                    Someone seems to think they can make money at it. Every once in a while I see a truck here in Jersey for a firm that cleans PV panels. Here's one:
                    I had a hard time finding the PV panels page on their website. It certainly makes sense for a cleaning company to answer 'Yes' if someone asks them to clean solar panels. But I wonder how often they actually quote a figure for someone, and how often that figure is accepted.

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                      #11
                      I have a 5 KW array on this property I am working at currently. Sometimes I clean them weekly depending on how the dirt is flying around here. Generally at least once a month.
                      Microwave Radiation Dangers should be openly discussed

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                        #12
                        A PV array should be cleaned when the energy gained from the cleaning has more value than the cost of the cleaning. Of course figuring that out is complicated, many default to cleaning at specified intervals, or not at all.

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                          #13
                          Originally posted by pv_n00b View Post
                          A PV array should be cleaned when the energy gained from the cleaning has more value than the cost of the cleaning. Of course figuring that out is complicated, many default to cleaning at specified intervals, or not at all.
                          I saw a presentation for a big ground mounted PV system in Dubai. The rows had to be far enough apart for the custom module cleaning vehicle to drive between them. They have very bad conditions for module soiling - a whole lot of wind entrained dust and virtually no rain.

                          Comment


                            #14
                            Originally posted by ggunn View Post

                            I saw a presentation for a big ground mounted PV system in Dubai. The rows had to be far enough apart for the custom module cleaning vehicle to drive between them. They have very bad conditions for module soiling - a whole lot of wind entrained dust and virtually no rain.
                            I finally got my sawmill setup in my solar shed and was doing some cutting for several hours. Afterwords I looked at the roof and could see a thin layer of sawdust. Fortunately, nor shortage of rain around here.......
                            Ethan Brush - East West Electric. NY, WA. MA

                            "You can't generalize"

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