Cleaning Panels Difference

[skepticcyclist]

Never thought I would have to clean my panels during what is normally the wettest month of the year for CA, but after 2 weeks of Santa Ana winds they were more dirty they they are during the dry summer months.

So did it make a difference?

You can see the slight uptick when I hosed them and they cooled (even though it was only in the 60s outside at the time), then a change in the curve after they were cleaned.

This is something I would normally never even think to do I February

 

[arnolddeleon]

It will be interesting to see how long it takes for the output to drop the same level they were before you cleaned them.

 

[SilverSp33d3r]

Following: my panels look terrible right now from dust/dew combo. Curious to see real world data on this!

 

[jboy210]

Strangely our roof is super clean even with 6 weeks of no rain. Must be all the frost melting off in the mornings.

@skepticcyclist that looks like a pretty health difference. It almost looks like output from an hour or so earlier.

 

[skepticcyclist]

It will be interesting to see how long it takes for the output to drop the same level they were before you cleaned them.

I will post the peak production tomorrow. Today peaked at 3.8 kW. I suspect tomorrow will be at least 100 watts more for peak. Dozens to 100 watts more for a whole day could easily provide more than 1 kWh extra for the whole day, even though it’s still winter.

 

[SilverSp33d3r]

I will post the peak production tomorrow. Today peaked at 3.8 kW. I suspect tomorrow will be at least 100 watts more for peak. Dozens to 100 watts more for a whole day could easily provide more than 1 kWh extra for the whole day, even though it’s still winter.

What size system do you have and what azimuth?

 

[skepticcyclist]

What size system do you have and what azimuth?

Panels are 5.99 kW DC combined. Microinverters convert to a total of 4.5 kW. It will max out at 4.5 kW for about an hour during the day duri by 2 months of mid summer.

I have 6 panels south, 4 west, and 9 east.

 

[skepticcyclist]

This is a typical clear June day. Don’t know how dirty they were then.

 

[SilverSp33d3r]

I haven’t had my system running for very long but this is today. You have inspired me to clean panels to see if I get any increased peak/total production.
12.24 system
18 E
16 W
2 S

 

[h2ofun]

Nah, not touching my panels.

 

[nwdiver]

It will be interesting to see how long it takes for the output to drop the same level they were before you cleaned them.

Peak dirt seems to happen at ~2 weeks 'round these parts. Then the dirt keeps more dirt off.

Another benefit to oversizing.... can't lose to dirt what you already lost to inverter saturation

 

[skepticcyclist]

Just as I predicted. It maxed out about 100 watts more, and was producing about 100 watts more each hour than it did yesterday at the same time. I will wait to see how much more total energy this is by the end of the day.

 

[tfan2018]

Just as I predicted. It maxed out about 100 watts more, and was producing about 100 watts more each hour than it did yesterday at the same time. I will wait to see how much more total energy this is by the end of the day.

great results! what are you using to clean the panels btw?

 

[skepticcyclist]

great results! what are you using to clean the panels btw?

Just a hose. We have soft-water. I added a hose valve to the pipe that enters the house after the soft water tank. I mostly use this for washing my cars. But also works well for hosing off the panels without leaving water spots.

 

[skepticcyclist]

Unfortunately doesn’t look like the weather is going to help us in the near future. May get up to 90 degrees here, normally in the 60s this time of year and sometimes will only reach into the upper 40s.

For those outside of CA and the west coast in general, the wettest season on the west coast is winter. February is the wettest month for CA. We get almost 100% of our rain during the 4 months from late fall to early spring. So even areas in the state that get 100+ inches (yes there are areas that get that), most of it falls in a 4 month period. We get 20 inches at my house and it all falls in 4 months. To have to wash panels in February is something I thought I would never have to do.

 

[skepticcyclist]

Ended up only 400 watt hours more total compared to yesterday. Don’t know how much daily fluctuation factored. It was about the same as last year when I didn’t have to clean my panels.

 

[SilverSp33d3r]

Ended up only 400 watt hours more total compared to yesterday. Don’t know how much daily fluctuation factored. It was about the same as last year when I didn’t have to clean my panels.

I would say that’s a win. I lost 300 wh today compared to yesterday.

 

[taphil]

I was down 0.6kwh today compared to yesterday, 8.16kw system facing almost due south.

 

[stagepuppy]

Adding my data to the collective... It's very dusty in the northern San Fernando Valley, LA area, I noticed my daily production dropped to 45KWh, after simple rinsing, production rose back up to 55KWh. There is still a sticky grime layer on the glass surface that will no doubt attract dust again, but I was surprised the dust was so bad to cause a 20%+ reduction in solar generation. Daily temps hovering in the mid 90Fs for the past 10 days with a few days more hazy but other days the usual few clouds if any. Please see images for the reduction trend over the last 6 weeks.

It peaked at 64KWh in April before the summer heat with still relatively clean panels on a 9.18KW/27 panel setup in 3 groups: 14 panels facing SE, 9 panels facing SE, and 4 panels facing NW, pitch estimated around 20 degrees for a typical Mid Century home. I did the rinsing around 6:45pm so the two big groups were already shaded, while the small group was catching the last of the setting sun. Similar to the OP, where the production curve is usually steepening downward, I got a small plateau for about 15min where it held for 0.3KW. Was already noticing the reduction in June (48KWh) when the day after some monsoonal rain (about 2 hours scattered showers) output jumped back up to 61KWh, this piqued my interest.

My friend in La Jolla said she got a 10% improvement after soaping down and rinsing her system. I guess it's not quite so dusty by the coast.

 

[jjrandorin]

My friend in La Jolla said she got a 10% improvement after soaping down and rinsing her system. I guess it's not quite so dusty by the coast.

I have the company that cleans my windows also clean the solar panels, which works out to be once a year. Mostly because they are here, they do a great job on my windows, and have also been cleaning solar panels for more than a decade.

They dont use any soap at all, just deionized water and a brush. I would be hesitant to use any actual soap or detergent type thing on them, if it were me. When I asked the owner of the business I have clean the windows / panels "why no soap?" he said, "you dont want any sort of residue on them, and its not necessary, just deionized water, a long handled brush, and some care in cleaning them is needed."

YMMV of course.