Is Solar Panel Cleaning A Waste Of Time And Money?

a bird shitting on a solar panel

Solar Panel Cleaning – It’s A Dirty Job, But Nobody Has To Do It

The day your solar panels are installed is the day you will get the best performance out of them.  After that it is all down hill. Admittedly, it is a very shallow hill and it might take over 40 years to get to the bottom, but day one is going to be as good as it gets.

One of the reasons for this is dirt. As soon as your panels are out in the open in the clean air, or not so clean air, dust will start to settle on them, blocking sunlight, reducing their efficiency, and costing you money.

The obvious solution is to pay someone to clean those panels, or get out there and clean them yourself. And sometimes this obvious solution will be a sensible course of action. If a dust storm has covered your panels in dirt or pelicans have had a poop party on your roof, then it’s a pretty good idea.

But most of the time solar panel cleaning is not worth it.

Because the average increase in output from cleaning panels is usually small, taking into account the time and risk of injury if you do it yourself or how much you will need to pay to have it done, under normal circumstances it is not cost effective.

It makes far more sense simply to install a slightly larger system to compensate for the minor loss that results from grime than it does to pay someone to clean them.  Or if your system is already installed, spending money on energy efficiency is far more cost effective than paying people to clean your panels.

Normal Grime Hardly Affects Solar Panels

Dirt on solar panels usually has very little effect on their performance.  This is because, for most homes in Australia, rainfall is enough to keep solar panels reasonably clean. Grime will build up, but eventually there will be sufficient rain to wash most of it off.

Cleaning in addition to what is done naturally by rain will boost panel output, since on average they will have even less dirt on them, but it doesn’t help much.

A study done in the United States in Tucson, Arizona, found that cleaning solar panels only improved their output by around 1%. This is in a location that only receives a little more than half as much rainfall as Adelaide, which is Australia’s driest capital.

This doesn’t mean that in your particular location cleaning panels will only improve average performance by 1%. You might happen to live in a dirty, dirty place or have lots of birds trying to turn your roof into the site of a future guano mine. But I would estimate that for most households in Australia, cleaning solar panels twice a year would only improve their average output by around 2%.

Flat Panels Are An Exception – They Need Cleaning

Rain will wash most of the filth off panels, but only if they are at an angle. When solar panels lie flat water can pool on them and have nowhere to go. Eventually it evaporates and leaves grime behind. Worse, things such as leaves and other debris can land on solar panels and just stay there and seriously affect performance. A thin layer of grime will let most light pass through, but a leaf is specifically designed to capture light. After all, it is a naturally occurring type of solar panel.

To avoid these problems, and because it is bad to have any electronic item sitting in water for an extended period of time, it is a very good idea to put solar panels on flat roofs in frames that tilt them at least 10 degrees.

If your panels aren’t tilted then you’ll have no choice but to clean them if you want to keep their performance up. Google found that while cleaning their tilted solar panels wasn’t worth the effort, cleaning their flat ones after they got particularly dirty could double their output.

Frameless Panels Stay Cleaner At Low Angles

If you can’t avoid installing panels at an angle under a 10 degrees, frameless panels can help.  These have no metal frame around the edge and are often called glass-on-glass or double glass panels because the solar cells are the filling in a glass sandwich.  The lack of frame helps water flow off them and keep them clean.

Don’t Be Fooled By The Cool

You may may have heard people claim when they clean their panels it improves output by 10% or more.  And they may be right. Some people live in filthy, filthy places.  But it is easy to be fooled into thinking that cleaning panels has a greater effect than it does.

Firstly, cleaning panels will cool them down and cause them to operate more efficiently. If someone cleans hot panels when and immediately checks their performance and sees it has increased by 10%, that could be entirely due to the fact they are now 40 degrees cooler.

And even if you aren’t fooled by the cool and do get a significant, real improvement in performance, as soon as they have been cleaned those panels are going to start getting dirty again, so the average increase in performance from cleaning will be considerably less than the immediate increase that results.

Solar Panel Cleaning Costs Money

Professional solar panel cleaners insist on being paid for their services.  It doesn’t matter how much you bargain with them, they always refuse to do it for free.  Even my own children expect me to pay them money to clean solar panels and if I forget they’re up there and put the ladder away, they ask for hush money not to tell my ex-wife.

The amount of money you will be charged varies on where you live, how many storeys your home has, and how many panels you have to clean.  A reasonably common price is around $7.50 a panel for a one storey home or $10 a panel for a two storey home.  But they do have a minimum charge, so if you only have 4 panels don’t expect to get them cleaned for $30.

If you shop around you might be able to find someone who will clean your panels for under $5 each.  But note that less professional cleaners might be more inclined to make a mistake such as flushing a load of soap suds into your rainwater tank.

The Economics Of Paying For Solar Panel Cleaning Don’t Pan Out

Paying people to clean your solar panels costs more than it’s worth.  Even in a situation that is as close to being best case as is realistically possible.

Let’s say you rescue a panel cleaner’s poodle from drowning during the great poodle flood of ’07.   As a reward she gives you a great deal on cleaning panels, only $5 each, and you pay her to clean them twice a year.

Your rooftop solar system is 5 kilowatts with 20 panels.  It’s in a sunny location that, without cleaning, generates an average of 25 kilowatt-hours a day. You have a 44 cent feed-in tariff and because you are never home during the day you receive it for every kilowatt-hour generated.

If solar panel cleaning twice a year results in a 2% increase in average solar generation, then you will earn around an extra $80 a year, but you will have spent $400 having your panels cleaned. So even under excellent circumstances it makes no financial sense.  Even if having your panels cleaned twice a year increased their average output by 10% a year, which is extremely unlikely, you would only just break even.

Because the above situation is about as good as it can get, most people will actually be far worse off. For example, a Sydney household with a similar sized north facing system that has a 6 cent feed-in tariff, self consumes 50% of the solar electricity they generate, and pays 25 cents a kilowatt-hour for grid electricity, would only save approximately $21 off their electricity bills each year if cleaning results in a 2% increase in average solar panel output. So there is really no way having your panels cleaned can pay for itself.

Cleaning Panels Yourself May Not Make Economic Sense

Paying someone to clean your panels doesn’t make economic sense, but what about doing it yourself? That has to be cheaper, right?  Well, that depends on how valuable your time is to you and what value you place on your own neck.  Or at least having a neck that functions as it is supposed to.

Let’s say you value your time at the Australian minimum wage of $17.70.  If it takes you 20 minutes to clean your panels, doing it twice a year will cost you about $12 worth of time. As a 2% increase in output can save someone with a 5 kilowatt system over $20 a year, cleaning panels yourself can be worthwhile.  But this calculation leaves out a major cost and I am not talking about water or detergent.

Each time you climb up on your roof, or use a ladder to spray water onto your solar panels, there is a small but real chance you will fall off and injure or kill yourself. If you value your life at $10 million and you think there is a one in a million chance you will accidentally kill yourself each time you clean your solar panels, then pricing in that risk adds another $10 each time. This means cleaning you solar panels yourself may not pay either, provided you place a high value on your own life.

But if you clean your panels just by spraying them with a hose from the ground, you are probably not in any great danger. You are very unlikely to accidentally strangle yourself with the hose, or experience a sudden surge in water pressure that kills you with exploding rubber hose shrapnel.

Don’t Clean Panels – Install A Larger System

Installing a slightly larger solar system to compensate for losses from dirt costs less than paying someone to clean panels.  One extra panel on a 20 panel system increases its output by around 5% which is more than twice the average loss I would expect from not cleaning them.  Installing a system one panel larger will definitely cost less than the $600 or more it could cost to have your panels cleaned 4 times.  One extra panel can more than compensate for loses from dirt for the entire life of the system.

While adding panels to an existing solar system is often not practical, there are still plenty of things people can do that will save them more money and have greater environmental benefit than paying for panel cleaning.  For example, they could invest in insulation, LED lighting, a heat pump hot water system, or buy a bicycle and use it for some trips instead of a car.

If You Want Pay For Clean Panels, Please Go Ahead.

If you want to pay to have your solar panels cleaned, please go right ahead.  Don’t let me stop you.  Just be aware that most of the time it will cost more money than it is worth.

I have no desire to put solar panel cleaning companies out of business, so if you decide against having your panels cleaned, please consider hiring them to do something else you will find worthwhile.   For example, some solar panel cleaners also do windows.

For those interested in cleaning their solar panels themselves, regardless of whether or not it makes economic sense, I will write an article on the best way to go about it very soon.

About Ronald Brakels

Many years ago now, Ronald Brakels was born in Toowoomba. He first rose to international prominence when his township took up a collection to send him to Japan, which was the furthest they could manage with the money they raised. He became passionately interested in environmental matters upon his return to Australia when the local Mayor met him at the airport and explained it was far too dangerous for him to return to Toowoomba on account of climate change and mutant attack goats. Ronald then moved to a property in the Adelaide Hills where he now lives with his horse, Tonto 23.

Comments

  1. Would they charge less for just a short story compared to a trilogy?

  2. Jack Wallace says:

    We’ll have to stop meeting like this, young fella!
    There was an ancient piece of wisdom to the effect that if you wanted any job done as quickly and easily (ie ‘efficiently’) as possible, give it to the laziest man you know.
    The solution to cleaning solar panels ~ and at the same time encouraging the ….er, ‘smart-arse’ (splurt!-arsed??) magpie to seek less feather-ruffling targets ~ is to crank up the old fire-pump and let fly from the comfort of your lawn.

    Not only do you get rid of the bird and the shit, you actually recycle the water by way of flushing out your gutters and watering (along with fertilizing!) your gardens at the other end of the downpipe.

    😉

  3. Hate to be pedantic, but houses don’t have ‘stories’ usually, but they can have ‘storeys’. At least I think that was the case when I was a young fellow at school.

    • Ronald Brakels says:

      I am so, so sorry for you, ramjetski. You hate to be pedantic? I can’t even begin to imagine what that must be like. You have my condolences.

      And thank you for pointing out my spelling error. It’s all fixed up now.

    • Jack Wallace says:

      Presumably you went to school in SA….or QLD.
      And just for the record:- small investigations often reveal stories in and about houses.
      ….though it really is impossible to knit picks.
      ….or even pricks, according to Shakespeare

    • Jeremy Hart says:

      Thank god someone else knows the existence of this word! I thought I was going mad! Storeys not stories!

  4. Jack Wallace says:

    hehehe…..Meanwhile, in SA ~ and soon to be coming to a power-grid near you ~ a bit of a storm (which storms are slated to become more frequent and ferocious with global warming) has wiped out power supplies and therefore water-supplies and sewerage-disposal, etc..
    Except for those non-trendy luddites who decided to go Stand-alone and DIY before the….er, shit hit the cumulonimbus cloud. Their supplementary wind-turbines will be churning out power like a politician does promises!

  5. Paul Rosato says:

    Mr Brakels, although there are a number of points in your article we could have a healthy debate on all day, (considering my profession is inspecting and cleaning solar panel systems), your guidance to readers on the hazards of working at heights and the risks associated with having someone other than a professional provide solar panel cleaning services is extremely wise!

    There is certainly a lot more at stake (life/injury or system damage) under these circumstances.

    Thanks for your insight from the other side of the coin.

  6. I’ve just cleaned my panels this afternoon – first time since they were installed 8 years ago. Peak output is 1.9kW on a 2.2kW system in the middle of Summer with a maximum 15kWh generated during a sunny day. Not sure if that’s a normal attrition rate for the age of the panels.

    No brainer for me to do as I was already cleaning the gutters. Will see if performance differs tomorrow but the panels are noticeably cleaner.

    • Cleaning was worthwhile. Averaging around an extra 2kWh per day with the most increase being when the sun is low in the sky or overcast conditions.

  7. warren Harvey says:

    I’ve always cleaned my panels about every six months since they were installed 15 years ago and to that end, placed the panels on a separate frame built low down so that the panels were easily assessable. Luckily I suppose, I had the space surrounding the house, to do so. I cannot believe how dirty the panels get sometimes, particularly after a long dry spell of weather when the panels are prone to get covered in dust. Then there is bird poo which sometimes covers several individual cells at the same time, adversely affecting a panels performance overall. NOT cleaning this muck off on a regular basis entices lichen to grow upon the glass surface of the panels, which further affects the panels performance. I’ve seen a few panels on older systems, belonging to people who have not taken the time to clean their panels, where lichen had covered almost the whole panel. I’ll continue to clean my panel’s on a regular basis thanks and advise anyone installing panels for the first time to consider cleaning them as an important part of solar power management.

    • Grace du Prie says:

      How do you clean them?

      • Hi Grace…. After the recent dust storms we experienced and no follow up rain, the covering of dirt on our panels became quite evident so it was time to give them a clean. I find it necessary to do this about every 12 months on average, regardless of rainfall – more if they appear to get bird poo on them or they get covered in dust. We rarely get any help from the rain to keep them clean anyway because we get so little where we are.

        I don’t take too much notice of those who say cleaning them doesn’t improve performance or is necessary. For the most part, I simply do it to satisfy myself that I’m getting the best possible performance from my panels that I can. Without going into figures, (too technical for me) I do see a small improvement in their output after cleaning, (according to the regulators) – and that suits me fine!

        When I do the cleaning, I begin in the morning whilst the dew (if any) is still on the panels. This seems to help loosen any grime or lichen etc. on the panels, which makes for easier removal of the same. I can access our panels from the ground (for personal convenience) They’re erected on their own separate built framework angled at approx. 27 degrees – not on a house roof.

        I connect up a hose and again wet the panels down thoroughly, then brush them down with a long handled window cleaning brush which I purchased from a window cleaning supply shop. I don’t seem to require any detergent for cleaning – just clean water seems to do the trick.

        It isn’t as easy to do as it used to be because the system has been extended over time and I now have to fully extend the brush handle and reach out and over to the top-most panels. It does the job very well however. Once I get one string of panels brushed, I hose them off and move onto the next section.

        Should panels be installed on a house roof, I would imagine the job of cleaning would be a lot more difficult, but in essence, the method of cleaning would need to be similar. You would need to plan to get onto the house roof each time when cleaning required it. However, if your physic and age – like me – are not quite up to the task of getting onto the roof, then you may just have to trust that the rainfall in your area is enough to do the job of cleaning the panels for you.

        Either way, I wouldn’t stress. My neighbour installed their solar panels on their house roof at the same time and they don’t seem to have had any issues with keeping them clean…..they simply don’t do it! Hope this helps. Cheers.

        • Grace du Prie says:

          Thank you so much! We have twice paid someone to clean the system. However, since my husband (72) still goes on the roof to clean the gutters I feel he should have no problem cleaning the panels. Since he is still working as a house painter too he has no problems with ladders and height. I just was not sure how to go about it. So thank you for your info on how to do it! That is saving some money again. We have 14 panels on the roof. Oh and…living in Ipswich Qld we hardly know anymore what rain is! We seem to go from drought to drought with once in a while a flood in between. 🙁

        • Unless you live where it rains every day there shouldn’t be any question about whether you should clean them or not but how? IF you can access them safely and use tap water and a brush you will definitely get a lot of the soiling off from them, the problem there is how do you dry them? If they air dry the minerals in the water dry on the glass and little by little make the surface rougher and more susceptible to hold dirt going forward. Like washing your car, if you can dry it before the air does it’ll be fine but that usually isn’t possible. We use deionized water so there is not residue of any kind and they dry completely spot and streak free. Pima County, AZ

  8. I was told to get my son (Plumber) to clean my panels once every 12 mths but not to worry for first 18 mths. I receive email every month to say my system is performing at 100 % so after 12 mths since they were installed I’ll leave it till the 18 mths are up . Love that my electricity bills are so low.

  9. Well thats all fine , have your panels set up under powerlines or a antenna , trees and they will be filthy in no time, or lichen can even stain solar panels ! So i say better to be safe than sorry they weren’t
    Given a once a year clean!

    Can also depend on where you live!

    At the end of the day it comes down to consumer choice!

  10. I often clean my car as “the rain” doesn’t seem to do what you say it does “clean glass” and as for if it is worth it! Aren’t solar panels an investment? Don’t cars need a service? Doesn’t the Warranty tell you what is needed?

    If your paying a solar cleaner more money than you are getting back then. No it’s not worth it! But if your solar cleaner can show you an improvement of 10-20%+ then do your maths!!

  11. Total waste of time cleaning solar panels. Repeated trials have not demonstrated any measurable improvement.
    Claiming a 1% difference is a joke as there are too many other factors involved for this to be significant.

    • I beg to differ – if it works for Google…. ! Following is not my work but have put the link to Google’s own blog for the sceptics.

      Google conducted a groundbreaking experiment at their 1.6 MW solar farm in Mountain View, California. They found that cleaning the solar was “the number one way to maximize the energy they produce.” Cleaning solar panels that had been in operation for 15 months doubled their output of electricity.[1]

      The same study also found that rain is not a satisfying way of cleaning solar panels. Solar panels that were cleaned professionally had a 12% higher output of electricity compared to those cleaned by rain.

      https://googleblog.blogspot.com.au/2009/07/should-you-spring-clean-your-solar.html

      • Not quite . Maybe you should have read the study properly before misquoting their findings.
        It clearly states that there is no advantage in cleaning solar panels that are installed on an angle. So that would include all panels installed in Australia.

        So my original claim is supported by the study you cite. Hopefully most people will realise this and stop paying for a service that has not benefit.

        Nice try Adam.

        • I don’t argue that there is some cleaning effect with rain Brian but not everyone can afford to have their panels installed on an angle – eg if they have a flat roof. And I can tell you my panels (that are on a good angle) definitely do not fully “self clean” in the rain and I live in Tassie where the air is probably cleaner than most Australian States. In addition to a dust film, I get tree-leaf sap and bird crap.

          I guess you never clean your car either because it always gets cleaned in the rain ? Try having a look at the side doors (which will be almost vertical) when it dries after a rain storm !

          As far as I am concerned with solar every little bit I can squeeze out of it the better. I would not pay to have my panels cleaned but am happy to get up there and do it myself for free.

  12. What if the day the solar panels were first installed was heavy overcast but day two it was sunny; which day then gives the best performance out of them? That is why I get out there and clean mine every second day and even though performance will not equal results of the first day it will at least perform equivalent to day two which is always greater than nothing performed on day one.

  13. Last I checked, 20×5 =100 x 2 = $200….??

  14. Steven Winfield says:

    Where did u learn all the B.S.above. You obviously don’t have solar but you would like to but you don’t have the money. I have had panels for 8yrs now and have not paid a power bill yet and I get an increase in output of 32 percent after cleaning. You sound like someone who doesn’t clean his car ever cause the rain will do the job you Richard Cranium. Don’t talk shit until you know what you’re taking about, that is factual.

    • No good getting angry at me. I’m just quoting results of several scientific trials, including the Google one quoted above, that clearly state that for panels installed at an angle (which should be all panels in Australia) there is no significant improvement in their performance if they are cleaned.

      Which is backed up by my own experience with the 90 odd panels that shows no measurable improvement after cleaning.

      Feel free to keep wasting your time cleaning (or money paying for someone else to clean) your panels if it makes you feel good.

    • ramjetski says:

      You must live in a very dirty and polluted area to get a 32% output improvement after washing your solar panels. Either that or your mathematics is somewhat awry. Can you prove your claims??

  15. Try this report on for size Brian ! If you can accept that your panels’ output may have degraded by even as little as 1% due to the effects of dust/pollution etc that the heaviest rain can’t get rid of then that is still a fair amount when multiplied across your stated 90 odd panels – and that is a direct loss to your hip pocket, day after day, year after year.

    Still each to their own. Some of us don’t notice TV interference apparently. As for me, I can’t stand a degraded picture.

    http://www.sciencedirect.com/science/article/pii/S1364032116000745

  16. I can accept that my panels may lose even more than 1%, especially when it hasn’t rained for a while but it still doesn’t make it worth it to clean them. Even when we were getting 60c/kWh gross it didn’t pay.

    Let’s say you clean them once a quarter: The best quarter possible for me would be 50kWh per day for 90 days (that would mean 90 cloudless days on the north coast of nsw – mpossible but exaggerated to make my point). That amounts to $30 per day. For 90 days is $2700. If they have been working at 1% less due to dirt I have lost $27. Hardly enough to justify me getting up to clean them and certainly not worth paying someone. Still not worth it at 2%. So In the current market with net metering it is even less viable to clean panels.

    Any study that claims a 1% improvement in efficiency after cleaning would struggle to show that 1% as statistically significant because there are dozens of other variables that can’t be controlled. The google study just confirms it.

    I’ve tried with my panels, unable to find a difference in output before cleaning and after cleaning on a couple of occasions, and that’s what sent me looking for results of research.

    The only point of note in the study you linked is the removal of bird droppings, lichen etc that may shade a portion of the panel may be useful.

    http://ucsdnews.ucsd.edu/pressrelease/cleaning_solar_panels_often_not_worth_the_cost_engineers_at_uc_san_diego_fi

    This study suggests that in areas where rainfall is low or for large arrays it might be justified. And other studies suggest in highly polluted or dusty areas it might be justified but most of Australia doesn’t fit that category.

    http://rollingwash.net/docs/Effects%20of%20Dust%20on%20the%20Performance%20of%20PV%20Panels.pdf

    Even this study shows an 18% reduction but only when the entire surface of the panel was smeared with mud nearly 50u thick.

    So I’m happy to moderate my “don’t bother cleaning under any circumstances” to “if you live in a city in China or India, or if the flying foxes keep shitting on your panels or if someone is smearing mud all over your panels you better get up there regularly and clean them”.

    Not sure that applies to many of us in Australia.

  17. Thanks Brian – this certainly is an interesting issue with people firmly entrenched in both camps. I do know that one of my panels is right under the TV antenna and is currently covered in bird poo. I’ve bought a plastic eagle to fly above the TV aerial and will install it to see if that keeps the little beggars away.

    I know this is somewhat off-topic but as we are talking panel (in)efficiencies I noticed a YouTube video the other day where it showed how you can get a reasonable increase in power output when the sun was reflected onto a test panel with a mirror. It got me thinking that there is a small fortune waiting for someone to come up with a substance, film or whatever that can be painted/applied onto existing panels that has minute particles in it that can reflect additional sunlight downwards onto the photo-voltaic material underneath the glass – even better, perhaps nano-particles that can adjust to follow the sun around and keep reflecting light at the optimally correct angle !

    Maybe Finn Peacock should have stayed with CSIRO a little longer !

    • Adam, I have panels directly under my TV antenna and they are still free of bird shit 12 months on.
      I used different lengths of cable ties on the antenna rails pointed vertically to discourage birds from landing. So far sparrows, doves, black birds, magpies and spangled drongos all fly past my antenna to rest on the neighbours!

      • LOL – thanks Andrew – may give some cable ties a try – many thanks for the suggestion and a lot cheaper than one of those plastic spikey things from Bunnings !

        The plastic eagle kept falling down and getting tangled in the aerial in strong winds and I couldn’t find an easy way to attach it higher than the antenna so it would appear menacing to any bird wanting to roost under it.

        You’ve reminded me to get up and clean the existing crap off and will try some cable ties whilst I am up there !

  18. We’ve had the solar panels cleaned professionally once; mounted on a very high 3-bay shed; may not make any difference in output as neighbours tall trees cast shadow from 2 pm in summer. Biggest problem is cleaning the gum leaves from under the panels. Suggestions? Thanks.

    • Ronald Brakels says:

      There is mesh that is used to stop animals from getting under solar panels and chewing on wires. That might stop gum leaves getting under your panels, although they might just pile up against the mesh.

  19. Brian Elvery says:

    Leaf blower.

  20. I can only comment on my own experience which shows cleaning does make a material difference.

    Prior to cleaning the peak in our system was about 4.75kw each day. After cleaning, the peak was over 5kw each day, the same as when installed.

    I was prompted to clean the panels as I kept noticing the peak decline over time. Our system is just over one year old.

    Thankfully I followed the instructions in the article and cleaned early in the morning.

  21. I am wondering does the maths work out better cor a cleaning every few years? Would a panel clean at 10 bucks per panel or so every 5 years be worth it. I guess not if the improvement is only ever at 2percent. Still, we are in the far north and so mould that will not easily wash away may slowly potentially hinder panel performance. My system is going great and we overbought to ensure cleaning was not essential but now thinking about a clean.
    I was also noticed small cracks in the silicon, is that likley to be a problem? When i say small i mean up to 5cm or so.

    • Ronald Brakels says:

      Generally filth does not build up on solar panels thanks to rain, so I wouldn’t expect a clean after 5 years to make much of a difference, but it will depend on your personal circumstances. If you can see your panels are building up grime that isn’t being removed by rain then a professional clean would be helpful.

      When you say there are small cracks in the silicon, I assume you mean the silicon sealant. Hopefully it is harmless, but if the deterioration becomes severe you can inform your installer. Or if you prefer you can directly contact the manufacturer.

  22. hi have had my 2kw x 12 panels removed, and replaced with a 5.5 kw 20 panels
    set up the 2kw x12 panels had been on roof for 8 yrs. could not believe how dirty they were could scrape the dirt of with scrape blade. wiil clean them
    every 12 mths now.

  23. Hi All,
    Wow, there are some differing points of view in this arena. Happy to say I am on the pro side for cleaning panels. After all it is the business I chose to be in. The information that is used on my face book site is relatively up to date within the last couple of years, not ten years old, and either from white papers, scientists, or from personal ‘on the job’ experience. Not from individuals that have an opinion because they own a single solar system array. That is like stating that you have a motor vehicle and because it’s always worked perfect, all motor vehicles work perfectly. I don’t know about the eastern states of Australia, but in the southern metro areas of Perth, our panels do get dirty. Some filthy and some not so bad. There are some ideas on the nay side here that may confuse some people. By saying panels may never need to be manually cleaned, is in itself going against what many manufactures explain in their warranty manuals under maintenance. I prefer getting advise from manufacturers. (checking your own manual is a good thing to do.) Manufacturers also say to check earth wiring, panel attachment points and overall condition of wiring and panels, at least yearly. Now that’s all good for the people that are happy to climb onto their roof and check, and good on them I reckon. But what about the people that don’t? Not all panels are easily visible from the ground, so how do they know what condition their panels are in. No one here talks about hot spot litigation or soft/hard shading on solar panels, and how much damage can be done long term to panels with these issues. There is some talk of ‘add on’ diodes that help in shading, but in reality how many systems have had this done. Unless everything is explained to the purchaser about their solar system, or they have done their homework, and they are willing to pay the extra, they are in the dark on this subject. Lets be honest here, some people are not happy to pay to get their TV aerial shifted when solar panels are being installed, but if they knew how much power they lose from shading they may change their minds. Solar panel systems are the same as any long term investment. They need to be maintained to get get maximum longevity and maximum benefit. A yearly maintenance clean and check should be carried out, either by yourself or a contractor. If you would like up to date info on why you should clean solar panels, you are more than welcome to visit my face book page. Seabreeze solar panel cleaning services. But be aware, because some photo’s may show hard soiling of a lot more than 1%. All photo’s are of actual jobs done by me and not taken from other sites.
    Clean panels = efficient panels

  24. Edward Schoenhoff says:

    You mention that panels work more efficiently when cooler,
    Can you do a cost/value breakdown, If you were to install a rooftop sprinkler system which would turn on every half an hour for 1 minute sprays.
    Would the reward of getting a higher Kw feed in outweigh the cost water used & initial installation.
    Thanks

    • Ronald Brakels says:

      Hi Edward

      For every 10 degrees increase in temperature a typical solar panel will produce 4% less energy. That’s 4% less in total so a 17% efficient panel won’t fall to 13%. Instead it would be about 16.3%. Because good quality panels have fallen so far in price it doesn’t make economic sense to install a cooling system. It will always be cheaper to simply install more panels instead to make up for the losses. Even if you had maxed out the number of panels it is possible for you to install you’d be better off spending the money on energy efficiency measures such as more energy efficient appliances or insulation.

      Good quality panels have fallen so far in price there is no point in

  25. Yes, It’s all well and good to go on and on about a few dollars saved here or there, but there are other factors to be taken into consideration when contemplating having your panels cleaned.

    Fire hazard:- The amount of dry leaves and debris that I have cleaned out from under panels is frightening, even more frightening is the fact that the worst I have come across have been in schools.

    Rodent nests:- Nothing like having a rat run up your arm whilst your laying flat out on your stomach trying to get at the leaves from right under the panels. This leaf build up also seem to make great possum nests, bird nests and python snake habitats.

    Workmanship:- So many installers use nylon cable ties to tie there cables to the frame. These are not UV stabilised and simply fall off over time, leaving most of the harness laying directly on the roof usually amongst the previously mentioned leaf matter. I always replace them with stainless steel cable ties.

    System integrity:- Testing of the system from top to bottom to prove the system is operating within tolerances. I have been to many installations where the circuit breaker at the panels had tripped in the last thunder storm and the home owners were not aware that there solar system was not and had not produced a watt since then.

    Street appeal:- Filthy panels with a lot of moss growing over them just looks bad from the street. You have installed your solar system and feel good about going green. So why not keep the panels looking their best, just like the rest of your house.

    • No argument with the leaves, rats, cable ties, integrity, moss? (i think you will find it is lichen) and general health of the panels. The need to sort these issues is not part of this thread and there is plenty of reasons to do something about them.

      Back to cleaning panels.

      And the evidence (from several sources quoted in my previous posts) is that it is not worth the time if you do it yourself. And a waste of money if you can be talked/tricked into paying someone else to do it for you.

      How they look? Really?

  26. Hi Brian. I had to reply to you about your post. Do mind me asking what you do for a living? Are you a Seer, mind reader or time traveler? Because the majority of solar panel cleaners that I associate with, check and correct the points that Jeff is talking about in his post. I feel you have completely missed the point that Jeff is talking about, they all work together. It’s a thing called multi-skilling, or value adding and they are really easy to do together. For the majority of us, that’s what we do. First of all we are contacted to clean the panels. While we are up on the roof we also inspect the condition of the panels, check the wiring and have a look to see if there are any other issues in the area. And yes, if cable ties have broken and cables are freely hanging but still connected and coming into contact with the roof and have no damage, we correct that. If I see any damaged tiles or I damage a tile, I replace them. I notify the clients of the condition of panels. If the panels have spider cracks through them, photos are taken, info is written on the receipt and next time they are cleaned, a new report is done.

    Opinions are like arseholes, we all have one. But I would recommend that you make sure your opinion is backed up by some hard facts. As for the moss, you state that you will find it’s lichen. You were not there, so your opinion of that is baseless and has no justification, except for your own validity that you know all in this grand land. I have come across both moss and lichen growth whilst cleaning panels.

    Before starting out in this business I knuckled down, read a lot of research into the subject, as to whether it was viable for myself and to the client. The majority of scientific white paper testing that has been done, is overseas and done in a controlled environment, mainly dealing with different types of dust particles. Many of these state that bird scat and other environmental fallout were not part of these tests and there needs to be more scientific testing into these because outcomes would be extremely different. Sadly, not enough testing has been done in Australia. Some will argue that Australia is different to the countries where tests have been conducted, but with a quick check on the net, this is one comment:

    Australia is a land of extremes with temperatures ranging from highs of 40°C in the central desert regions to below freezing in the higher regions of the country’s southeast. Sometimes these extremes can be experienced on a single day.

    From its northern most point at 10° 41′ 21″S on Cape York to the southern tip of Tasmania at 43° 38′ 40″S, Australia experiences almost every climatic condition encountered elsewhere in the world, along with some that are unique. One of the most significant features of Australia’s climate is its long, hot and often dry summers.

    Understanding the above, it is comical how some people figure that because their panels are free of bird scat, lichen, moss and leaves, they have the belief that all panels are the same.

    It is only your personal assumption that solar panel cleaning is not worth the time to do yourself, or get them cleaned professionally. There is more than enough evidence out there to humbly accept that your statement is flawed. Sometimes people only read what is relevant to their wanted outcome. But I do take offense to being noted as a trickster and would hope that you have some good hard core evidence to back up that statement.

    As to your last comment, How they look? Really?
    I personally have never heard of this for solar panels, but people clean or get their residential windows, cars, boats, caravans etc cleaned for that very reason, of looking good and pay good money to get this done. Once again you feel the need to question Jeff for this comment, but again you have no idea of whether this is Jeff’s comment, or a reason that a client asked Jeff to clean their panels. Hence my comment, Opinions are like arseholes we all have one, but sometimes are they not worth listening to.

    To aid people in making their own minds up, here are some links that may help them.

    computerworld.com/article/2971726/environment/rain-could-make-your-solar-panels-dirtier-not-cleaner.html

    quora.com/How-important-is-to-keep-your-solar-panels-clean

    solar-facts-and-advice.com/solar-panel-cleaning.html

    LG and Bosch are some of the leaders in solar panel manufacturing, and as such, have spent a lot of money on research and development in keeping solar panels clean, nano technology is at the fore front of this development. Even these two company’s understand the need to keep panels clean. But for all the R&D, they openly understand that their newest technology still needs maintenance cleaning and states this in their operating and installation guides.

    I for one would prefer to follow manufacturer guidelines, than comments from individuals with limited or no factual experience.

    For more info on solar panel cleaning visit my facebook site.
    Seabreeze solar panel cleaning. Located in western Australia.

  27. I love the article and the like arguing comments that I can have knowledge for the some issues that I never encounter. I am grateful for the brilliant ideas you shared in here, I am looking forward to have some more ideas from all of you guys. Keep it up!

    • Ronald Brakels says:

      A three person household in Sydney uses an average of around 5,400 kilowatt-hours a year. An electric car that gets 5.5 kilometers per kilowatt-hour and is driven the average annual distance for a passenger car of 14,000 kilometers will use 2,500 kilowatt-hours a year. So a home and an electric car will consumer roughly 7,000 kilowatt-hours a year. As a rule of thumb, one kilowatt of north facing panels will generate an average of around 4 kilowatt-hours a day. So 4.8 kilowatts of solar panels will produce around 7,000 kilowatt-hours a year.

      In other words, a typical household will need a 5 kilowatt solar system to provide electrical energy equal to the consumption of the home and an electric car.

  28. I find blog to be fake news, why do I say that? The author obviously has no clue what reality is. Sunpower the largest solar panel manufacturer with the best product with millions of solar modules installed at schools, homes, commercial even utility scale installations where upto a million panels have been installed.

    Sunpower and many other companies like Tesla and SunRun, and thousands of homeowners which add up to many thousands of installations pay us to wash the solar panels sometimes 1 to 4 times a year. Even Google pays us to clean thier solar panels, The Apple building in Cupertino California with 20,000 panels are cleaned once a month. Apple tells us they get a 50% increase of production when we clean them once a month VS once a year. Losing 50% production is akin to having 10,000 panels not working. The lack of production creates demand for cleaning, the cost of cleaning is a investment that pays a return in power production that can add up to 3 to 4 times what it cost to keep them clean.

    This information the author is providing is for solar systems in drier desert areas where there is no dew set and therefore no dirt sticks to the panels. In areas like Saudi Arabia where they even use a giant truck mounted leaf blower to blow off the dust. This is a very small percentage of installations across the globe. To put a blanket comment that it does not make sense to clean solar panels is pure malarkey.

    Cost to clean residential panels is not based on how many panels there is.
    So to say someone anyone would clean 4 solar panels for $20.00 is not real. How can you own a truck pay for gas , have the right equipment , have the proper insurance and then get on someone’s roof for $20,00. We charge between $100.00 and $125.00 for a residential solar panel cleaning, Which covers using the right equipment, having insured workers earning a living wage. Our customers know you wont have issues if we break something since we charge enough to stay in business. Our repeat customers, thousands of them will tell you cleaning is about the most important thing you can do for your solar assets. Basically before you decide not to use a professional solar panels cleaner ask yourself, is it worth it to not clean your panels when you spent thousands to get em installed?

    • Practical says:

      There is no evidence from scientific trials that have been carried out to show that cleaning results in anything more than one or two percent increase in energy production. Even if this was a statistically significant Improvement it is not enough to pay for the cleaning. Unless there are extremes like animal turds or sap from overhanging trees there is no scientific evidence to suggest that you should do anything more than make sure the panels are still in one piece.

      • Hi, Practical. Seems to me, you may only be reading research that validates what you want as an outcome. But I am more than happy to help you see some ideas from people in the know. I am sure that a senior scientist at Carnegie Melon University’s knows what he is talking about. please check it out at, https://www.pcworld.com/article/2971692/consumer-tech-science/rain-could-make-your-solar-panels-dirtier-not-cleaner.html.
        I almost find it laughable, that the anti panel cleaning brigade struggle to find any unbiased evidence.
        Hopefully if you are an owner of a solar system, you would have bothered to read your manual, under the heading of maintenance!!! As I’m sure manufacturers also know what they are talking about.

        • Sorry but you have confused a comment by a researcher for a scientific study.
          It’s not research. You have quoted an opinion of one person and it hasn’t been tested. Even the title brings up a red flag – “Rain could make your solar panels dirtier, not cleaner”. Doesn’t say it does and nothing in the article suggests they have tested that hypothesis. The fact that it’s in PC World and not a scientific journal is another problem.

          A study takes many sites, repeats the experiment and collects data over a period of time then analyses the results using statistics. Like this https://ucsdnews.ucsd.edu/pressrelease/cleaning_solar_panels_often_not_worth_the_cost_engineers_at_uc_san_diego_fi . “Don’t hire someone to wash your dirty solar panels. That’s the conclusion of a study recently conducted by a team of engineers at the University of California, San Diego.” Yes, they found it increased output – but too small an amount to pay for the cleaning or justify you own time to clean them.

          Or this one: https://googleblog.blogspot.com/2009/07/should-you-spring-clean-your-solar.html?_ga=2.22371771.1098633121.1535773955-477316959.1535773955 . Their conclusion? “Our data indicates that rain does a sufficient job of cleaning the tilted solar panels. Some dirt does accumulate in the corners, but the resulting reduction in energy output is fairly small — and cleaning tilted panels does not significantly increase their energy production. So for now, we’ll let Mother Nature take care of cleaning our rooftop panels.”

          Go ahead and pay someone to clean you panels but you are throwing money away or if you do it yourself find something else to do.

          What’s laughable is there are people out there trying to sell owners of panels a solution for a problem that doesn’t exist.

          Happy to read a study that can justify cleaning because I’ve go nearly 100 panels. And just for the record I’ve compared their output before and after cleaning and couldn’t measure any difference. Which is why I started to some research of my own.

          • Hi Practical,
            Thanks for the reply.
            Correct me if I am wrong, for I maybe a couple of rungs down the ladder from you on the intellect scale, are you saying that a researcher doing a scientific study is not research?

            I perused both of the links you supplied, so thanks for the reading. As I said in my first reply, I like unbiased evidence. Maybe you yourself failed to read the first link in totality, I have cut and pasted this for you out of the link.
            (But solar panels heavily soiled with bird droppings should be cleaned. That’s because the droppings essentially block all sunlight and will not be washed away when it rains. Engineers also found that at a few sites, photovoltaic panels were dirty enough to warrant cleaning due to very specific and localized circumstances. For example, being directly next to and downwind of a highway, factory or agricultural field may generate enough dirt to warrant cleaning.) By the way I am unsure about August 2013 being recent.

            I fear that for the second link you may have fallen on your own sword here, only because as you have stated, that if it’s not from a scientific journal it’s a problem. Your second link is from a 2009 google blog, now that’s a long, long, long way from a scientific journal, is it not.

            Was it worth me reading both links though? yes it was.

            You are incorrect in saying that I am quoting the opinion of one person, all I have done, is shown you and others, that enjoy this blog, a link to some information, far from a quote I feel. I understand and believe that you have a solar array and for you there is no reason for you to clean them, that’s great and I am sure that some people may be slightly envious of that. But putting a blanket statement of no solar panels require cleaning is unrealistic. After all, your only one man making a one off personal statement.

            I am not here to change peoples opinions, but to give realistic input into this blog, something of which, some people struggle to achieve.

            For myself seeing is believing, and I for sure believe.

          • Darrel. I mentioned cleaning due to unusual events like bird droppings/ bat droppings (in my area) in an earlier post. And yes it is justfied. The blog is not a scientific journal but the study it quotes was carried out using scientific method. Point is cleaning is not economically justified in most cases. Read the post from Ronald that introduces this thread.
            The essence of the studies is if you want to clean your panels go ahead but don’t try and kid people that it is necessary or economically viable at the feed in tariffs we get.

      • Practical says, no need to bath for your skin will flake off as nature intended.
        I read a scientific paper written by deodorant companies who claim you don’t need to bath all you need is our product….get real Practical I am sure at least, I hope you bath at least twice a week.

        So you actually think science prepared and paid for by utility companies is worth reading let alone real science. The facts are solar panels do need to be clean to work at thier best performance. Utility companies even pay universities to do research and when it shows anything the utility companies don’t like they squash the reports. I can say they have been somewhat successful in brain washing some folks to believe they don’t need washing. I did get a call from one person out of thousands who wanted to argue with me about the return on investment and quoted one of those fake news reports. I told him go ahead and dont clean them and see for yourself. I told him to call me back when he come to your senses. Six months later or so he called and asked me to inspect his system telling me something must be BROKEN since production is very low. As I assumed it was so dirty no amount of rain would clean it even if it did rain in MAY. which it doesn’t do very much around here.

        When I told him it’s just dirt and did he want me to wash them he said a resounding YES. When I charged him $150.00 he said he was paying over $600.00 per month in utility costs. Instantly his costs went below $100.00 per month and when it dipped three months later he called me again and paid $150,00. He also told me that article was full it and thanked me for being patient with him. He also told me that $300 he spent saved him over $400 per month for the duration of the summer until it did rain again. $300 saved him $1200.00 in utility costs. So think about it how many folks who own solar read that fake news and act upon it costing them hundreds and possibly thousands of dollars that goes to the utility companies and its stockholders.

        Then someone like you comes along with no actual experience other then reading fake news and then acts on it like it is gospel. It just goes to show you that some people can be fooled some of the time and some can be fooled all the time. I do think people who own solar and somehow find this blog knows the difference between what Practical says and reality.

  29. Jack McFlackertyback says:

    Why is the article based on cleaning twice per year and based purely on economics? How about cleaning every 5 years or so just purely to maintain them? Is the author saying they should never be cleaned?

  30. SolarEngineer says:

    There are several factors to consider. I work in the solar industry as a performance engineer, and have analyzed soiling on carport systems in Southern and Northern CA at 5 degree tilt. They get absolutely filthy, and I have seen greater than 20% decreases in power output due to soiling. For example, after a professional wash, a SoCal (San Diego area) system’s peak output went from 108kW to 134kW, a gain of 24%.

    Other aspects which can benefit from clean modules are module degradation and long-term operation. Non-uniform soiling can accelerate module degradation, and if bird droppings are present, can result in accelerated module failure. It is most certainly site specific to determine what is the best route for maintenance or lack thereof.

  31. Hi Practical,
    Thanks for replying. It is enjoyable that we can have conversations of this nature.
    Here is a scientific review for you to peruse if you choose to.

    http://www.sciencedirect.com/science/article/pii/S1364032116000745#bbib36

    Its a long but good read that opens up on some of the grey areas on how some of the research is achieved. It has some very good relevance to the last link I sent you, that you so easily dismissed as having little relevance and no depth. After all, you said you went looking for research, normally a person searching for research, who has no bias, would not see any red flags, by just seeing the title.

    As you have stated, (“What’s laughable is there are people out there trying to sell owners of panels a solution for a problem that doesn’t exist”).

    You then state (that cleaning due to unusual events like bird droppings/ bat droppings (in my area) in an earlier post. And yes it is justified).

    Are you playing dirty politics here? Your saw want happened to Mr Turnbull when he tried to cover up the truth about the banks, didn’t you?

    It may be unusual for you, but not other areas. Australia has many different environmental climates.
    The quote below is from another scientific research that I can supply to you if you would like.
    (B.
    Bird Droppings
    Bird droppings were frequently observed on every modules
    and were removed from the dirty cells. This was done because
    bird droppings were not part of soling loss studies and would
    jeopardize the entire experiment. If they were not removed
    carefully it would have ended in inaccurate results. A sharp
    tool was used to remove it from the modules carefully without
    scratching the surface of the solar cells. Initially bird droppings
    were creating a lot of problems. In order to keep
    the birds away from the solar cells metal spikes were placed on top of the solar modules in such a way that it casted no shade on the cell
    surface. The attachment of metal spikes on the photovoltaic
    modules declined the bird droppings to a great extent).

    One could say by removing the bird droppings off all test panels, it would render the whole research as a failure, as those areas have now been cleaned.

    One area of concern I have is with the second link you kindly attached. Even though they believe that sand in the corner of each panel is only causing small losses, the sand in the picture would be classed as hard soiling, which can cause hot spots on modules, and as we all know, this leads to premature failure of panels. Is this not another benefit for cleaning solar panels?

    Anyhow, as I said at the start of this little blog today.
    It is enjoyable that we can have conversations of this nature, that are based on both sides being truthful and of credible nature, why? Knowing from the very start it was you, Brian, running as an alias. Your ethics have now been exposed for what you are, a person that can’t be taken seriously for any of your blogs and you have the gall to call honest Solar panel cleaning businesses tricksters. You have now proved that you personally well and truly deserve that status.
    You are Practical by name but not nature.

    I hope now, that people who come onto this blog wanting to get fair and ethical feedback, now understand the tactics that some people go to.

    Just a little word of advise Brian, next time you want to play alias, change your AVATAR.

    Regards,
    Darrell

  32. Hi Adam,

    Yes it appears that Brian has dug a rather large hole for himself.

    As long as practical is the only alias on this blog, it would be sad, but not unrealistic if “Brian” could also be an alias.

    I suppose it’s up to Ronald, being the adjudicator of this blog, to decide whether to allow Brian to add further input into this blog. Outwardly “Deceptive” people should be held to account.

    Ronald is in a hard space though, because it appears that Brian, was his most loyal ally.

  33. Ronald Brakels says:

    Sometimes I read through comments and think I must have written some horribly one sided, unbalanced articles when I was younger. But then I reread the article and I think — nah.

  34. If you want to get your panels cleaned go ahead but (long story short) genuine research (not my opinion, someone’s anecdotal experience or someone else’s opinion) is that it does not make ECONOMIC sense. Doesn’t mean they don’t get dirty. Doesn’t mean that cleaning won’t improve their output. Just means that in general the decrease in output when they are dirty isn’t enough to justify spending money or time to clean them. Because the increase in their output, at the rates we get paid for solar feed, doesn’t cover the cost.

    Doesn’t mean that panels never need cleaning. For panels with extraordinary dust, bird, flying fox, salt spray, dirt accumulated in the corner there may be an economic argument that favours paying to have them cleaned regularly – maybe every couple of years. I Suggest you do the calculations before forking out.

    To the respondents attacking the man not the message? I’m not trying to hide. If I was trying to “hide” under an alias I wouldn’t have referred to previous posts that i’d made.

    Wrt agreeing with Ronald Brakels? It is pretty hard not to. He researches his articles thoroughly and provides structured arguments. Unlike the respondents to my posts who attack the person and confuse anecdotal evidence with research.

    I can only conclude that the people who don’t like the message are those trying to earn a living from cleaning panels. No need to stress as there are plenty of gullible people around.

  35. I’m wondering if what you say applies in the tropics. My panels get a lot of mold and can be a bit hard to clean. I’m not sure if mold allows much sun through and I’m not sure studies in SA or the Nevada Desert are very relevant.

    • Ronald Brakels says:

      I have seen pictures of panels with moss built up on their bottom edge, although I haven’t seen anything like that here in South Australia. If moss is starting to cover solar cells I definitely recommend cleaning that off or having it cleaned off.

  36. I can confirm that I have seen moss AND Lichen on the same west-facing panels here in Adelaide.
    Salisbury North to be exact. In 2015 my wife and I moved to Adelaide from FNQ and initially housesat our way around Adelaide as a means of finding a suitable suburb to buy in.
    This house at Salisbury North had panels in place for just a few years when I arrived.
    The house owner fed the birds every day and as a result the top knot pigeon, dove and sparrow populations hung around on his and neighbouring rooves as feeding time drew near.
    The mess was appalling – I could see from the ground that the panels had streaks of droppings on them. It was only when I got on the roof to clean them, that I saw the moss and lichen.
    A soft broom, detergent, elbow grease and a good hose pressure soon cleaned them up and the difference in readings was amazing.

  37. George Schueler says:

    Before rain maximum output on a 20 panel E-W facing system was 3800W mid day.
    After 50 mm rain output rose to 5100W mid day.
    No rain for 4 months and little for previous 5 months.
    washing wit rain seems to help.

    • If you hadn’t had virtually any rain for 9 months then there would have been a layer of dust built up on the panels which would have a similar effect I’d imagine as an overcast day if the dust was impeding the rays getting through the glass to the solar film. The rain would have cleared the worst of it but I’d almost guarantee that it didn’t wash it all off just as rain doesn’t wash all of the film of dust and dirt from your car.

      If your numbers are right then 1300 kw/h odd a day multiplied by many months is money lost ! If climate change continues to make Australia drier for extended periods then washing panels in cases such as yours will definitely be cost effective.

Speak Your Mind

*

GET THE SOLARQUOTES WEEKLY NEWSLETTER