Wildfires, ash, and cleaning rooftop solar panels

[jeffy1021]

PSA - If you have rooftop solar and live in an area affected by wildfire smoke/ash, give your panels a quick scrub down. I just did and am producing +10% compared to yesterday. Figured if my cars were covered in ash, so were my panels. Simply hosing them off isn't sufficient (unless you have a power washer).

To add my $0.02 about the original topic, I plan to stay on EV-A until it goes away. Fortunately I have SW facing panels.

 

[ohmman]

PSA - If you have rooftop solar and live in an area affected by wildfire smoke/ash, give your panels a quick scrub down. I just did and am producing +10% compared to yesterday. Figured if my cars were covered in ash, so were my panels. Simply hosing them off isn't sufficient (unless you have a power washer).

To add my $0.02 about the original topic, I plan to stay on EV-A until it goes away. Fortunately I have SW facing panels.

Thanks. Just finished. Progress photo shows how bad they were. Generation was plateaued at 5kW and jumped to 6.1kW. Some portion of that was likely cooling of the panels by spraying them down.

 

[astrorob]

argh, i am seeing this too - i just paid someone to clean them last year and now i gotta do it again. 2 story house so there's no way i'm getting up on the roof myself. looks like almost -16% here.

i wonder if i should just wait until fire season is completely over?

 

[bmah]

Annoyingly the best I could do is spray off about half of my panels from a ladder. They're actually much higher up than it seems, looking from the ground. Doing any better requires a pressure washer (don't have one) or climbing up on the roof (fear of heights outweighs annoyance caused by lower solar production). Going to call in somebody to deal with this at some point.

Bruce.

 

[Owner]

I looked at my usage and generation and it really isn't that different other than the short power outages we had.

I may get out the giant ladder and just hose them off.

Bad air but no ash.

 

[Uncle Paul]

Wonder if that spray cleaning kit from Fuller Brush or Windex would get them cleaner than just spraying with plain water.

I use those systems from time to time to clean my 2nd story windows when I am too lazy to get up on the ladder. Works pretty well, but not as good as a squeege.

 

[ohmman]

I used a 5 gallon bucket filled with dish soap and water, a hose, and a microfiber mop. I sprayed them down (from the roof), dipped the mop in the soapy water, washed each panel, flipped the mop over and hosed the ash off, then repeated for the entire array. Despite my "hose the ash off the mop" step, the bucket was as black as a can of black paint by the time I was done. Quite disgusting.

Can you tell when I was cleaning them? FWIW, I was generating about 35kWh in the clear days prior to cleaning them and generated 38.5kWh today. So just about 10% improvement overall.

 

[ecarfan]

I typically clean my 34 panels twice a year; late spring and fall. It’s definitely time to do it now that the ash fall has ceased. I normally see about a 5% power generation increase with cleaning, but this year it certainly could be more!

 

[ecarfan]

My panels were very dirty. Panels in foreground not yet washed when I took this photo. Previous washing was this past June. Compared yesterday to today; 6.1kW peak output yesterday and today was 6.6kW (clear skies both days).

 

[jboy210]

I wish I could wash my SolarRoof. The downside of SolarGlass is it is like ice when wet. And my roof is close to 3 stories high so I am not going up there!

 

[mblakele]

For folks who can't get up on their own roof, how should we think about the ROI of paying to have panels cleaned?

Let's say I expect my panels to produce an amortized value of about $1000 annually. Reducing that by 10-20% for a full year = $100-200. But maybe assuming a full year is too simple, because rain in November might help a little, and dirt will start accumulating again. Any thoughts?

 

[ohmman]

For folks who can't get up on their own roof, how should we think about the ROI of paying to have panels cleaned?

Let's say I expect my panels to produce an amortized value of about $1000 annually. Reducing that by 10-20% for a full year = $100-200. But maybe assuming a full year is too simple, because rain in November might help a little, and dirt will start accumulating again. Any thoughts?

This is a worthwhile exercise, though probably pretty complicated. I think you want to ensure that you're looking at absolute annual value from the panels, not merely the net. And my experience is that rain helps with dust, but does not clean the panels well in our area since pollen and other particulates have effectively baked onto the panel over the course of many months.

A cursory search says that getting panels cleaned can cost $150-350, depending on the array size and roof configuration. So I think you're right that from a purely ROI perspective, annual cleaning may not be warranted for smaller arrays.

 

[SMAlset]

My panels were very dirty. Panels in foreground not yet washed when I took this photo. Previous washing was this past June. Compared yesterday to today; 6.1kW peak output yesterday and today was 6.6kW (clear skies both days).

View attachment 591929

Yuck. Looks like my car right now. So I'm sure our panels (no PTO yet) look the same. In preparation for winter rains have a roofing company coming out in early October to do a general inspection of tiles and vents on the house, flashings, screens on vents, moss on some of the northern tiles along with gutter cleaning. Will have to check and see if they do panel cleaning as well. Two-story house as well so leaving to the pros. Roof mainenance yearly or whenever is worth doing for many reasons.

 

[maximizese]

I typically clean my panels once or twice a year, when the panels get really dirty with no rain in the forecast (haven't seen rain 7 months so far). I ended up cleaning my panels and skylights in late September and got them so clean I would eat off them. I took the time to clear my rain gutters and inspect the flashings too. I started with my leaf blower, then hosed everything down with light water pressure, used a microfiber mitt to scrub the glass with some basic car wash soap, and followed up with a thorough rinse.

I do this while there's cloud-coverage and no direct sunlight for hours. The whole thing takes about 45 minutes and I see a small gain in energy production ~3-5%. I've got SolarEdge optimizers on each panel and not sure if that minimizes the production loss when the panels are dirty.

 

[mblakele]

This is a worthwhile exercise, though probably pretty complicated. I think you want to ensure that you're looking at absolute annual value from the panels, not merely the net. And my experience is that rain helps with dust, but does not clean the panels well in our area since pollen and other particulates have effectively baked onto the panel over the course of many months.

A cursory search says that getting panels cleaned can cost $150-350, depending on the array size and roof configuration. So I think you're right that from a purely ROI perspective, annual cleaning may not be warranted for smaller arrays.

Thanks for that good advice. I ended up having my 15 panels cleaned for about $150. My reasoning was that it might not be worthwhile, but I couldn’t know for certain without trying it at least once. It turned out to improve generation by about 45%. The panels hadn’t been cleaned since installation about three years ago.

After looking back at the data I’m inclined to think that it’ll be worthwhile to have them cleaned every 18-24 months, or whenever they drop under 80% of first-year output. That didn’t happen until the last couple of months, which I attribute to ashfall from the nearby fires. The worst case, of course, is that we'll see another big ashfall right away.

 

[jboy210]

Thanks for that good advice. I ended up having my 15 panels cleaned for about $150. My reasoning was that it might not be worthwhile, but I couldn’t know for certain without trying it at least once. It turned out to improve generation by about 45%. The panels hadn’t been cleaned since installation about three years ago.

After looking back at the data I’m inclined to think that it’ll be worthwhile to have them cleaned every 18-24 months, or whenever they drop under 80% of first-year output. That didn’t happen until the last couple of months, which I attribute to ashfall from the nearby fires. The worst case, of course, is that we'll see another big ashfall right away.

45% improvement is impressive.

We are having our SolarRoof cleaned this week. They are charging $285 which I think is good for cleaning 3,000+ feet of roof. We also are having them clean the gutters. The Solarglass install left an amazing amount of metal trim scraps, screws, etc. flowing into the gutters.

 

[bmah]

Had our gutters cleared and panels cleaned today. The fellow who we have do this stuff said a lot of people’s panels had a lot of gunk on them and he needed to scrub the panels (not just hose them off). He took this photo before he got started:

It’s kind of cloudy and rainy now so no quantitative measures of how much this helped.

Bruce.

 

[SMAlset]

We have a scheduled appointment to get ours cleaned after all the wildfire ash. Timing is now iffy as appt is tomorrow afternoon when of course we have a 90% chance of rain for the afternoon/evening. After the initial light rain we received recently my husband said we did have improved production. Took a bit extra to get the ash off our cars so still think we’ll benefit from having a thorough panel cleaning than what rain will provide.

 

[jboy210]

We had our SolarRoof cleaned recently and I think it helped. Nothing dramatic though. Because of shading, we were down to 6 kWh/day. Now running about 7.2 kWh. But, the change could be as much that it has been slightly cloudy and that seems to more evenly illuminate the roof.

FWIW, the service we used could only clean parts of the roof but did get all of the active areas. The problem is their poles were only 20 feet long and would have needed to be close to 30 feet, or they could have walked on the roof. Waiting to see how the rains do at cleaning the roof.

 

[SUN-day Driver]

I wonder if it would make sense for some panel manufacturer to make a self-cleaning model with a wiper blade. There could be a rain sensor and when the panel gets sufficiently wet, give it a wipe. Maybe not as good as a soapy mopping, but a wet wiping every time it rains would surely be better than nothing for those of us with high roofs we're not going to climb around on.