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Bando:
Good Morning !
1.) I thought the whole point of this exercise is to discuss and perhaps examine how dirt affects solar system performance. I believe I care some about the subject.
2.) I'd suggest that while the eye may be a good subjective tool to qualitatively gauge how dirty something is, and a great tool to gauge when it may be time to do something about it, the quantitative determination of system performance is probably best handled using the eye and other tools.
3.) To clear something up, I don't believe I ever said (or wrote to be correct about it), anything you wrote is wrong. I believe I acknowledged what you wrote about solar panel dirt as most certainly valid opinion and worthy of respect. FWIW, I believe that. I also said I appreciated your work and encouraged you to continue. I believe that also. I'd respectfully request you do not ascribe statements to me that I did not make.
4.) Nor can I find anywhere writing my data is "right", or yours is "wrong". There is no right or wrong in experiment. You may think that's what I wrote, but I have no control over what you infer or project.
5.) Most or all of the weather related parameters I mentioned including, to use your reference: "geography, topology, wind, sun, irradiance, temps, etc" and, I might add others have, in my opinion, an effect, some of them a rather pronounced effect, on how much dirt accumulates on a solar panel. Therefore, contrary to your statement: "but you haven't mentioned anything dirt related", I'd suggest, and my opinion is, that I may have mentioned one or two or more things that are influential in how much dirt accumulates on a panel, therefore dirt related and therefore influential on system performance.
6.) I'd suggest that thinking that "particles per square inch" is one or perhaps the only way to measure dirt on a panel shows a certain amount of ignorance about the subject. For starters, I think the purpose of the exercise is to study the effect of dirt on performance, not measure the quantity of material deposited on a surface.
7.) My results are applicable to my situation only, and only for the dates I mentioned. That is implicit in the nature of experiment. My results do not apply to you, or anyone else. I believe that's part of the nature of experiment as I learned it and practiced it. I attempted an experiment as described. I took my data. I reported my results. I suggested conclusions based on those results. Others may well come to similar or different conclusions. To the extent that the results of any experiment allow others to gain knowledge or insight about the subject, so much the better. That's one goal.
8.) You may very well have improved your performance 5% or more by cleaning your panels. Maybe 10% for all I know. My data leads me to believe my stuff got less dirty in a somewhat similar climate to yours for about the same time period. That's all. No more. I'd add however, that my conclusions at least in the form of opinions, while not better or worse than yours or anyone else's, have some recorded data behind them that may be useful for analysis and criticism.
9.)My whole point is that your methods, while laudable, useful and valid, are mostly anecdotal and therefore probably do not warrant the accuracy you ascribe to them.
10.) Mine don't either. I believe mine are a dart throw. I think I stated as much.
11.) If you believe I disagree with almost anything you post, So be it. FWIW, while respecting other opinions and trying not to be offensive, a lot of your stuff is worthy of disagreement. Mine too. Nothing personal. When I do disagree, I try to give reasons for the disagreement. I try to do the same when I strongly agree. Opinions vary. (FWIW, I agree with the compliments you've paid me)
12.) I don't think it's possible, nor did I attempt to invalidate your results. I stated that I'm of the opinion what you have done does not warrant the confidence you seem to have in the conclusions you have reached. I stand by that opinion.
13.) FWIW, I'm not a rocket scientist either. Just tryin' to call 'um like I see 'um.Comment
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i would suggest you go back and read your comments and how they come off - maybe you can leave out the snarky comments and condescending lectures.
these threads in this forum are largely anecdotal. last time i checked, anecdotal evidence is not prohibited in this forum or by law. anything from cleaning tips (dirt or snow removal), to how one felt about their installer, etc - it's all anecdotal. as such, results and opinions vary.
if you choose to crunch numbers and validate everything with a calculator, by all means, go for it. no one is telling you to believe any of the anecdotal "stuff" presented on this forum. if someone writes "the sky is pink", maybe you'd say no it's not. and maybe i'd say yes the colors at dusk are beautiful. so to each his own, but please, keep the snarky attitude out of it.Comment
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i get that - i'm a CPA and crunch numbers for a living. what i'm trying to point out is that people's experiences, interpretations and use of available data are going to vary. that is true with accounting and auditing too, btw. the concepts of materiality, scope and reasonableness are just as important as anything you can punch into a calculator.Comment
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Well, I cleaned my 44 panels for the first time today. Bought the cleaning tools a few months ago but never had to clean thanks to frequent rains. But it hasn't rained for a while and the panels are dirty enough to warrant a cleaning, so I was eager to try it out today.
I have 44 panels lined up in 4 rows and 11 columns (length of panels are vertical). I bought a 30 ft extension fiber glass water fed pole with a brush head for $175 and a filter setup with a 10" carbon filter followed by a 10" DI filter for $125.. Roof is pitched at 23 degrees. The idea is to use filtered water to clean and let it dry to a spotless dry.
Earlier in the morning, I went up on top of the roof (with safety harness tethered to an anchor point at the roof ridge), and cleaned from the top of the roof. Only needed about 25 ft of the pole, so took the last piece of the pole out to lighten it up. Took about an hour to finish. Waited for it to dry, and noticed that the last 2 bottom rows were still not totally clean. I was pretty disappointed. They looked clean when they were wet, but after they dried out, I could see some dirt streaks remaining. The problem is that I could lift up the brush head to rinse out the dirt on the top 2 rows. But the pole got too long on the last 2 rows that it was impossible to lift up the brush head to rinse on the last 2 rows.
Being tethered to the roof anchor point gave me some confidence to move around the roof with more ease. But boy, the last trip down without being tethered to the anchor point and all achy and tired wasn't fun. I was on all four crawling down backward very slowly to be safe, LOL.
So I decided to wait until the sun is down to clean the bottom 2 rows again, but using another approach. Instead of getting up to the top of the roof ridge like before (not looking forward to have to walk the roof again), I decided to clean from below on the ladder, which is safer. I would climb up and stand on the ladder at the bottom of the roof and push the pole upward. There's 10 foot of roof between the bottom of the last row and the bottom of the roof. I decided to clean all 4 rows while I was at it. So I used the whole 30 ft of the pole to push it up all the way to the top row. I needed all 30 ft of the pole because the 4 rows are about 20 ft and there's another 10 ft between the bottom row and the end bottom of the roof. I'd clean 2 columns at a time (8 panels total), then move the ladder to the next 2 columns to clean them, and so on.
One other thing I decided to do is to not use the filter the second time around. The reason is that my water is EXTREMELY high in TDS (750 ppm on TDS reading), so the morning cleaning session that took about an hour pretty much got my DI cartridge all shot. So I don't want to use filtered water the whole time anymore, but instead just use it for the final rinse to conserve DI resins. That's the same strategy Mr Clean DI cleaning system uses. Clean thoroughly with regular hard water first, then use final rinse only with DI.
So I took the cartridges out and cleaned with just hard water direct from the hose. I know I've said before that I was against spraying/cleaning the panels with very hard water because of the water stains it'd leave. So my strategy was to clean with regular (hard) water first, so that I can take my time and make sure all the dirt are brushed off. Then come back and clean more quickly a second round with filtered water to rinse off the stain. Unfortunately, I ran out of time and it got too dark by the time I was done with cleaning with hard water, I was not able to do another pass with filtered DI water again. So I'll just have to wait until tomorrow morning to see how the panels dry out and see if I need to rinse out the hard water stain or not.
Overall, I felt more comfortable cleaning upward from the ground (well from the ladder actually) than cleaning downward from the roof ridge. Mainly because I felt safer standing on the ladder instead of standing and walking around on the roof. I might have felt more comfortable walking the roof if I had flat shingles roof with firm grip. But I have curved tile roof and you have to be more careful not to get tripped up walking on the more slippery curved tiles. And more importantly, walk on the right spots on the tiles to avoid breaking them. Another reason is that I'm not encumbered wearing a harness and have the tethering rope lying around getting in the way.
So my future strategy will be cleaning from the ladder in the future, with plain hard water first, taking my time to make sure I clean it thoroughly, then do a final rinse with filtered water last so they dry into a spot free dry.
Update: I checked out the panels this morning and they still don't look clean enough. Lesson learned is that just a few passes of the brush is not enough to get the dirt off. The glass looks deceivingly clean when wet. But the dirt stubbornly clings to the glass surface, and once the glass dries out, the dirt rears its ugly head again. You really have to brush over it really well several times to make sure the dirt is gone. The 23 degree pitch doesn't help either because the pitch is not deep enough to let gravity do the work for you pulling the dirt off with water.Comment
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Volusiano, the TDS (total dissolved solids) reading of 750 ppm is not a direct reading of hardness. To get a proper reading of hardness, you need to get a hardness test kit. I have a TDS meter on my reverse osmosis drinking water system and it reads 426 and my home has a 48,000 grain water softener installed. My incoming water to the house is 12 grains of hardness. I just replaced our water softener and it is only a month old. I have not tested the hardness of the water softener output, but you get the slippery feeling like the soap will not completely rinse off and the glass shower enclosures do not show any spotting. The TDS reading of your water might be things that do not affect hardness.Comment
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Both TDS and grains per gallon measuring systems indicate the hardness of the water, just in different way. There's no wrong way or right way.
My RO drinking system reads about 75 ppm TDS on the output, with about 750 ppm TDS on the input. This reading is for the Total Dissolved Solids. For pure water measurement, you want your filter output to have between 0-10 ppm TDS reading. This is what professional window cleaners use (TDS reading) when they use water fed pole pure water cleaning. All they care about is that the output of their carbon/RO/DI filtration system is between 0-10 ppm TDS in order for their cleaned windows to dry without spotting. They don't use a water hardness kit in measuring how pure their water is in terms of grains per gallon.
My city water hardness averages about 16.5 grains per gallon, with the high of 20 gpg. This is the measure of water hardness by the city, and this is the number to be used to set for your water softener. So yeah, the water softener uses a different way of measuring water hardness. But it doesn't mean that it's wrong to use the TDS reading as another way to measure water hardness. It's just 2 different ways to measure it.
But there's a difference between soft water and pure water. Soft water produced by a water softener exchanges the mineral ions in the hard water (like calcium and magnesium) with salt ions from the water softener. So the output of the water softener is soft water, but it's not pure water. If your water is very hard, while your water softener outputs "soft" water, if you take the TDS reading of this soft water, you'll find it to be about the same value as the TDS value of your hard water. Why? Because before, the TDS is for calcium and magnesium content; and after, the TDS is for salt ions. Different dissolved solids, but same amount, hence same TDS readings both ways. So soft water is not pure water because its TDS reading is just as high.
I also have a 40K gallon capacity water softener. My soft water comes out nice and soft, feels slimy on the skin, makes soaping up very easy, as expected. But after it dries out on my glass shower door, I can still see salt spots on the glass. That's an indication of the soft water not being the same as pure water. Only RO and DI can remove the total dissolved solids. Water softener doesn't remove TDS, it only exchanges one kind of ion with another kind, the salt kind that makes it easier to soap up.Comment
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That's an interesting idea and I've seen people using Jet Dry on windows cleaning and claim that it dries to a spot free finish. But I'm leary of putting any kind of solution on the panels other than plain water because the chemicals may affect the seals on the panels.Comment
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Actually Slopoke corrected me by saying that TDS is not a direct indication of hardness. Most people who talk about hardness refer to grains per gallon. So I'll rephrase my statement and will say that my water is EXTREMELY high in TDS value at 750 ppm. And I'll also rephrase and say that my water is EXTREMELY hard at 20 grains per gallon. Hope this clarifies things.Comment
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I bought 2 10" filter cartridges that are connected together. The first cartridge in the flow has a charcoal canister and the second cartridge in the flow has a DI resin canister. Professional Water Fed Pole folks use a much bigger system that usually is a charcoal to RO to DI system in that order that costs up to $2K easily. If you can use RO before DI, the cost of filtration will lower dramatically, because DI resin is much more expensive to replace.
So mine is a much smaller system with just charcoal and DI. It does the job fine and when brand new, I get very low (under 10) TDS reading on the output. The problem is that such a small system can get shot pretty quickly with a large volume of water flowing through it. That's why when used for car wash, everything should be washed thoroughly with regular (hard water) first, then only the final rinse is with DI water for a spot free dry. I'm going to adopt the same approach for my solar panel cleaning -> clean thoroughly with regular water first, then do a final rinse with DI water.Comment
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