Anyone with good cleaning tips?

[bando]

We have had a pretty bad drought here in So Cal and our panels have been getting very dusty every day. To make matters worse, the night temps fall into the 40's while the day temps are in the 70's and 80's, meaning there is a significant amount of morning dew and condensation dripping down the panels, creating this 6" bleed line at the bottom that is basically CAKED-ON dirt.

I got a $8 brass nozzle jet for the hose and was able to spray down the panels as much as I could, but the smaller array is pretty high up and the nozzle barely reaches them.

The day after I sprayed, the larger array looked about 60-70% better, but you can still see the bottom portion has caked on dirt. After doing my cleaning, we are breaking the 50kwh mark now for 2 days straight, so my ballpark guess is that we are experiencing roughly a 5% loss in output from dirty panels ... When are panels were brand new, I actually saw instantaneous power readings of 10+ a few times, but for weeks they have not gone above 9. (BTW, is there a way to see max power on a daily basis on Locus?) So that would suggest to me that perfectly clean panels vs what we have now could be an even bigger loss of up to 15%.

I didn't think I would need to address this so early into our solar system's life, but apparently it's going to be this way as long as we get the morning dews dragging the dirt down to the 6" mark , and no real rain to really wash away the dirt on a regular basis.

Does anyone have any tools or suggestions for reaching panels that are higher up? We do have a power washer but I was hoping a simple garden hose and nozzle would do the trick. Maybe a power washer would be better at removing some of the stuff that's really stuck on there. We also purchased a 12' telescoping pole with microfiber cleaner and squeegee, but it's still not long enough to reach the smaller array without actually getting on the roof.

I can live with some power output loss, but to be honest the larger array looked pretty dirty and bad, and I just wanted to get the dirt off. I suppose we will have to get up there and really clean them just to satisfy our own curiosity to see how much loss is a result of the dirt.

[russ]

Do not use the pressure washer - to easy to damage the seal on the panels.

[bando]

Do not use the pressure washer - to easy to damage the seal on the panels.

thank you. glad to have asked before trying!

i wish the panels didn't have that "lip" on the bottom and the water and dirt could just run straight off without collecting and drying on the surface

[J.P.M.]

We have had a pretty bad drought here in So Cal and our panels have been getting very dusty every day. To make matters worse, the night temps fall into the 40's while the day temps are in the 70's and 80's, meaning there is a significant amount of morning dew and condensation dripping down the panels, creating this 6" bleed line at the bottom that is basically CAKED-ON dirt.

I got a $8 brass nozzle jet for the hose and was able to spray down the panels as much as I could, but the smaller array is pretty high up and the nozzle barely reaches them.

The day after I sprayed, the larger array looked about 60-70% better, but you can still see the bottom portion has caked on dirt. After doing my cleaning, we are breaking the 50kwh mark now for 2 days straight, so my ballpark guess is that we are experiencing roughly a 5% loss in output from dirty panels ... When are panels were brand new, I actually saw instantaneous power readings of 10+ a few times, but for weeks they have not gone above 9. (BTW, is there a way to see max power on a daily basis on Locus?) So that would suggest to me that perfectly clean panels vs what we have now could be an even bigger loss of up to 15%.

I didn't think I would need to address this so early into our solar system's life, but apparently it's going to be this way as long as we get the morning dews dragging the dirt down to the 6" mark , and no real rain to really wash away the dirt on a regular basis.

Does anyone have any tools or suggestions for reaching panels that are higher up? We do have a power washer but I was hoping a simple garden hose and nozzle would do the trick. Maybe a power washer would be better at removing some of the stuff that's really stuck on there. We also purchased a 12' telescoping pole with microfiber cleaner and squeegee, but it's still not long enough to reach the smaller array without actually getting on the roof.

I can live with some power output loss, but to be honest the larger array looked pretty dirty and bad, and I just wanted to get the dirt off. I suppose we will have to get up there and really clean them just to satisfy our own curiosity to see how much loss is a result of the dirt.

Funny you should mention it. Since yesterday and today (I'm wagering) will be nearly identical solar irradiance except for 1/13 to 1/14 increase day/day, as an experiment I washed my array with water and a soft cloth on a 10 ft. extension pole about 0715 this A.M . I'll see if I can identify a difference after I compare array output and irradiance levels as recorded by my weather station for the 2 days. This is 1st wash since array assembly mid Oct. Early data today seems to show not much diff., but S.P. monitor crapped out after 0900 this A.M. which happens on a regular basis. Their monitoring is not real reliable IMO and a disappointment to me. Stay tuned - film at 11.

BTW, when you array was new, the sun was a lot "higher" in the sky your output will be greater then than now because of the lower angle that the sun makes with the line normal to the array during the day.

[bando]

Funny you should mention it. Since yesterday and today (I'm wagering) will be nearly identical solar irradiance except for 1/13 to 1/14 increase day/day, as an experiment I washed my array with water and a soft cloth on a 10 ft. extension pole about 0715 this A.M . I'll see if I can identify a difference after I compare array output and irradiance levels as recorded by my weather station for the 2 days. This is 1st wash since array assembly mid Oct. Early data today seems to show not much diff., but S.P. monitor crapped out after 0900 this A.M. which happens on a regular basis. Their monitoring is not real reliable IMO and a disappointment to me. Stay tuned - film at 11.

BTW, when you array was new, the sun was a lot "higher" in the sky your output will be greater then than now because of the lower angle that the sun makes with the line normal to the array during the day.

ok great, looking forward to your results! and you are right - our 10kw+ readings were all in the first week of december ...

i don't know why we get so much dust around here, it's not a super new area, although there has been some road construction about 1/2 mile east of me in Santaluz. very annoying that the panels look so gross already. how did yours look before washing? maybe the SP run off dirt/dust better?

[silversaver]

I did clean my panels once just to test if I can clean them on my own. Bought the brass nozzle from HomeDepot seem to do the trick. My ladder weren't tall enough so I jump on top of my patio cover lol As I recall, there's people will come to clean the solar panel for $80 if you don't have the access to your roof top. My suggestion is wait for rain if you cannot access to your roof top, you don't want to end up with more broken tiles on the roof........

[bonaire]

I did clean my panels once just to test if I can clean them on my own. Bought the brass nozzle from HomeDepot seem to do the trick. My ladder weren't tall enough so I jump on top of my patio cover lol As I recall, there's people will come to clean the solar panel for $80 if you don't have the access to your roof top. My suggestion is wait for rain if you cannot access to your roof top, you don't want to end up with more broken tiles on the roof........

$80 is a lot. For one visit or a season? What is the value of differential between clean and dirty for power output? I cleaned my panels in PA one time and got 2-3% improved output after a dry week. But we have enough rain that cleaning is not needed.

[silversaver]

$80 is a lot. For one visit or a season? What is the value of differential between clean and dirty for power output? I cleaned my panels in PA one time and got 2-3% improved output after a dry week. But we have enough rain that cleaning is not needed.

I do think $80 is reasonable. They have to drive to your house and do the cleaning, maybe once or twice per year. But, for 2 to 3% gain of energy vs $80 + risk of broken tiles? I guess I'll wait for raining season...

[Ian S]

Cleaning My Panels Increased Maximum Power By About 6%

I had a chance to look at before and after cleaning earlier this month (Phoenix AZ). Cleaning consisted of a rinse with water followed by spray wash with car wash detergent (gentle since it's designed not to remove car wax) followed by another thorough rinse. It's easy for me as I have a flat roof. The panels had only the odd rain shower to clean them for the past several months and were fairly dusty. I chose maximum power for comparison and maximum temperature for a temperature correction factor as the two would occur within a couple of hours of each other. All days were cloudless; I would have added additional days after cleaning except clouds came in on January 6. I also used a Tcorr of -0.2%/degF. I got the temperature data from weatherunderground's historical data. The SunPower 230 panels were installed in May, 2012.

ScreenHunter_01 Jan. 14 14.37.jpg

[bando]

I had a chance to look at before and after cleaning earlier this month (Phoenix AZ). Cleaning consisted of a rinse with water followed by spray wash with car wash detergent (gentle since it's designed not to remove car wax) followed by another thorough rinse. It's easy for me as I have a flat roof. The panels had only the odd rain shower to clean them for the past several months and were fairly dusty. I chose maximum power for comparison and maximum temperature for a temperature correction factor as the two would occur within a couple of hours of each other. All days were cloudless; I would have added additional days after cleaning except clouds came in on January 6. I also used a Tcorr of -0.2%/degF. I got the temperature data from weatherunderground's historical data. The SunPower 230 panels were installed in May, 2012.

[ATTACH=CONFIG]3586[/ATTACH]

that's a great spreadsheet thanks!

i experienced about the same increase. we were maxing out at 47-48kwh per day and now are over 50 with "clean" panels. i imagine if my husband goes up on the roof w/ the cloth and squeegee we might be able to get another 5%. we have a big bird dropping on one of them too, maybe the diameter of a baseball.

i don't know if i'd pay a guy $80 to clean them, but a loss of 5% will add to up $80 pretty quickly if you do nothing. so perhaps it is worth it once a year to get them super smooth and clean again, because even with hosing them down, a fine layer of dirt remains.

i'm going to try a few different spray nozzles and see if i can't get something to go a little higher to reach the smaller array. the brass nozzle i got from HD is good but maxes out at about 20 ft.

[bando]

i should add that if it weren't so early in our solar life, i don't know if i'd care. i find myself trying to save energy (like turning off lights even if i leave the room for a few minutes and come back) after getting solar, which is ironic given that i didn't do that before. i'm obsessed with getting "negative" use days which is more entertaining than useful

we are way over production for December (about 40% more than expected) and on pace to go way over for January too, so i guess i shouldn't worry so much. i have a neighbor who has had her panels for 5 years and said they never even touch them and it's fine. so i suppose that is what i'll end up doing in another year.

but our big array is right over the garage and it's just very noticeable when you pull up to the house and see how dirty it is. i don't think i could help but hose them off. who knew that my grey-brown concrete tiles hid dirt so well?

[Volusiano]

If your roof pitch is steep enough and it's only single story, maybe you can get a extendable water-fed pole (WFP) and try to clean from the ground. The concept of WFP is to clean with filtered water fed to the brush so that you don't need to squeezee dry the cleaning area. You just let the clean water dry by itself and once dry, there will be no spot because it's filtered water. The main advantage of WFP is that you can safely clean from the ground and don't have to climb up on ladders for cleaning.

My area has VERY hard water. You're talking about 700-800 ppm TDS reading on the average. So I would never just try to hose off my panels from the ground because the stain spots will remain on the panels after they dry out. Then it'd be even much harder to clean the hard mineral spots off next time. If you have very hard water, the only way to clean using hard water is if you can squeezee off the hard water before it dries out and leaves spot stains on the panels -> you have to be on the roof.

Anyway, water fed poles are not cheap if you get the carbon fiber kind (starting at $700 easily for a 25 ft pro model). But you can just get a fiber glass pole for much less ($175 extendable to 30 ft with hose and brush). It's a little heavier and more flex than the carbon fiber, but good enough to do the job. You need to do it only once in a while anyway. Also, most of the times, the brush will be resting on the panels and you'd just be pushing the brush around. Home Depot also sells the aluminum kind for a bit less (Unger 18 ft extension pole for $67), but it's heavier and 18 ft may not be long enough to reach from the ground.

For the water filter system, you can get a simple system with carbon in one 10" cartridge and DI (deionizer) in the next 10" cartridge that can run around $125. It may be good for a dozen cleaning before you need to replace the carbon and DI material -> not sure how much but maybe $50 for filter material -> $5/cleaning, not too bad. You can use this system to wash your outside windows or your cars, too. Let it dry off by itself to a spot free clean result. A professional filter system with carbon/RO/DI combination for high volume work can run around $2K easily. But a simple system like above just for cleaning your panels once in a while should be just fine. If you're lucky enough to live in an area where the water isn't too hard (maybe 50 ppm or less), you can try out rinsing 1 panel to see if you have issue with water spots or not. If not, then you may not need the filter system. Or if you still want the filter system, it'll last you a lot longer.

If a water fed pole can't be used on the ground to clean bottom up, then you'd have to get up on the roof to clean top down. Depending on how steep your roof is, and moreover, how brave you are, you'll now have to start consider safety issues and maybe wear a harness tethered to an anchor point while you're on the roof. Another option is to clean with the WFP from a ladder at the bottom of the roof to avoid being on the roof, yet solves your reach problem from the ground. I wouldn't recommend this unless you can secure your ladder to an anchor point like a gutter spacer or something tied to the roof, to keep the ladder from slipping off. The disadvantage with this approach is that you can only clean a section at a time before having to move your ladder to the next area and secure it again. Also water would be coming down at you, causing slippery condition.

[J.P.M.]

ok great, looking forward to your results! and you are right - our 10kw+ readings were all in the first week of december ...

i don't know why we get so much dust around here, it's not a super new area, although there has been some road construction about 1/2 mile east of me in Santaluz. very annoying that the panels look so gross already. how did yours look before washing? maybe the SP run off dirt/dust better?

Update:

S.P. Monitor still has holes in data of the type Ian may be familiar with from what he's written.
I'd expect resolution by morning. 01/15/2014. (?)
Don't know the best way to present the data. The Davis weather station data is 8-10 parameters each reported 1X/minute, including solar irradiance. The Sunpower monitor is 1X/5 min = 12X/hr. I've also got software (models) that are used as a check that gives theoretical clear day irradiance values given lat./long./el./various plug in atm. parameters like ozone/precip. H2O/dust/mixed gases/etc. I think I've got that type of stuff pretty well tuned in. Finally, the array has some shading (25-50%) this time of year from roughly after about 1500hrs. solar time +/- some from about 11/15 until about 01/25 or so. A.M. exposure is good/ no shading after 0730 hrs. or earlier all year.
One of my problems is I tell people how to build a watch when they ask me what time it is. I'm working on that too.

Will condense as much as possible ASAP and will share weather and S.P. data as asked. All in excel format.

System size:16 X 327 S.P., S.P./Power 1 inv., tilt, 18.5 deg., az., 195.5deg.

SWAG/RAW production data at this time :
01/13/14: dirty array: 23.91 kWhrs.
01/14/14: clean array: 24.19 kWhrs.

The raw weather data solar irradiance for the 13th is a bit higher for the 14th by 1.28%. That's backwards from what I might have expected given that the solar zenith angle is a bit higher on the 14th if the days had been truly identical, but then no days really are- these are not bad however. The higher wind may have added some dust. Theoretical (model/calculated) puts the horiz. irr. for the 14th about 1.0% higher than the 13th depending on which/who's model is used. The air both days was about as dry as a popcorn fart (in engineering parlance), more so on the 14th.
Data needs adjustment for irradiance, ambient temp., wind to SWAG effect of cleaning etc.. The 14th was warmer and windier. Don't know if I'll be able to isolate those effects accurately enough to make #'s meaningful or see if/what/any effect washing has. I'd caution that any results I come up with are little better than anecdotal without more data. Warmer amb. decreases output, windier probably increases output a bit, how much is a real bear. Stay tuned.

[russ]

With cement tiles you can walk on the with zero damage - you do have to be a bit careful is all.

I do it several times a year - a skylight offers easy access to the roof in my case.

[OvertheSun]

Could you put irrigation type sprinklers on the roof above the panels? Maybe the adjustable rotary type that distribute water evenly over short distance. I've seen similar set ups for fire protection.