Cleaning Solar Panels

Aaahhh. Music to my ears.

 

Hill, thanks for the reference to the Microsoft maps ... they are much higher resolution than Google Earth, and appear to be more up-to-date, as the bird's eye view actually show the panels I had installed in July, 2007.

I see your point re the 8kW system, although it does take a larger number of panels at current efficiency levels. I notice from the Sharp website that they have already surpassed the energy output in the panel size I purchased with their newer models, and I fully expect that trend to continue. I wouldn't be at all surprised if in 5 - 10 years the power output from a given PV panel size will be double or triple what it is now.

 

While increased output per sqft is nice, what is really needed is better output per $$. The encouraging thing is, that while the price per watt has remained fairly steady for a while, it has not gone UP with increased demand. I guess this translates in general terms to the price, in fact, going down.

Icarus

 

its sad that its up to private citizens to sacrifice their money in order to further a technology that is all win-win if cost is not considered.

 

4) It seems like I'm not getting the production that I was getting last year when the panels were new, is there a drop-off in production as panels age? I really won't know for sure until next August and we get to see what the production numbers are.[/quote]


I did not read all the posts so maybe this was covered- apologies if so-...but there is a type of panel that will degrade quickly in that first year, then stabilize. Amorphous silicone panels ('thin film' is one type) degrade in sunlight (!) so they are designed with excess capacity and will 'settle in' at rated power over the course of the first year. Uni-solar is one brand, there are several others

I wash mine off rarely, but would have no concerns with mild soaps. I just rinse and brush off if they get really dusty, a rare occurance.

 

In the real world, you shouldn't seem enough of a drop off in the first year(s) of a new install. Consider ways to monitor and log your production and compare it both to itself, as well as to a beta system of similar nature. Monitoring on an annual basis leaves you 364 days for a problem to show up on day 1.

I suggest you go here and find some info on monitoring :Solar Electric Discussion Forum - Powered by vBulletin

 

It may be the very thing mentioned in the title of the thread ... cleaning. I'd never realized that so many watts could be lost so quickly.

When we were accepting bids for our panels, it really shocked me how many sellers were quick to offer up innefficient panels, and low wattage to boot. Bigger profit margin for the cheeper ones? don't know. But yes, we ended up paying through the nose, so to speek when we opted for smaller footprint, 225 watt panels. In a couple years, when our 225's output look pathetic? It won't bother me really, as the better they get, hopefully they'll drop in cost, and more & more folks will come on board.

 

Hill is right,, from the solar forum : Amorphous panels (the non-crystalline types you typically find on cheap yard lights and other low end "solar devices" will lose 20% of their output capacity in sunlight (and, IIRC, it will continue to drop 20% every additional 6 months).

Don't know about the UniSolar... Tried a quick google and got one interesting report from ~1996-99--but they just gave the results for Vendor A, B, C, etc... Some were just fine, others had 50% failures (~11 watt panels used in Kenya).

I don't know of any installers that use Amorphous panels for installations,,, but as always I may be wrong.


What kind of installation do you have, or do you have selection of "harbor freight/ebay type panels?

PS I don't know the current status of Uni-Solar.

Icarus

 

Equally sad, in California, any excess output going back to your utility company (over a years average) is a windfall to the utility company. Legislation has been shot down that tries to correct that injustice. So much for incentivizing.

 

Maybe I can put some of this debate to rest. We've recently installed a system that incorporates microinverters on each panel, and we can remotely monitor the performance of each panel in (near) real-time. I have seen the production of our panels drop from near 200 watt/panel peak in April and May to around 160 watt?panel peak. I called the installer and asked about cleaning them, and I heard some of the advice given here - that cleaning them would do little to improve performance, though the act of washing them might cool them down a bit which could cause a momentary spike.

Well, I'm here to tell you that I saw an immediate 16% boost in the panels I washed. I am posting a link so you can see my panels - guess which two I cleaned

 

Post #2 - Edit - I have to make four more posts before I can submit a url. You guys certainly do not make it easy for a new-comer....

 

Post #3

 

Post #4

 

Post #5

 

OK - sorry about that - hopefully this one will work:

Enphase Energy - Enlighten | Wilt, Jim

 

I'm guess the two at the bottom right. Have any before/after pics of the panels? They must have been pretty dirty.

I cleaned mine off last week - panels weren't that dirty after a 3-4 months (don't recall the last time I cleaned them - think it was May?). I didn't notice a difference, but I also cleaned them all. Last time I ran a test by cleaning only some of them the difference wasn't significant for me.

FWIW - My best production seems to occur in May - cooler temps then. June seems to have more moisture in the air - and July tends to be significantly warmer. Typical per-panel output this time of year for me is around 145-150W - in May it's up around 165-170W.

If your panels are tilted south more than 10* you also have that working against you around June.

BTW - it looks like you are having some comms issues between your Envoy and panels? Seems that production readings are a bit erratic.

 

You guessed right. I'll try to snap some before/after (shouldn’t be too hard, as the rest of the panels are "before"). I've had them since the beginning of February, and they have not been cleaned yet. We live close to where the "Station Fire" was a couple of years ago and get a fair amount of sediment blowing off the hills.

Panels are not severely tilted, so that shouldn't be too big a problem. We are on a 20-year lease with SunRun, and they are supposed to do all the cleaning/maintaining. When I called, the rep told me that cleaning wouldn't make an appreciable difference, but I had to see for myself, which is why I got up there. Thing is, if the system does not meet their performance guarantees, they have to cut me a check, and right now, it is not doing what it is supposed to. Of course, if it is cheaper to pay me than it is to clean them... I've got a message in to them, so we'll see where this goes.

Regarding the comms issues - yes, that happens on occasion. If I put the Enphase module in the garage, the signal from the panels is great, but there is no Ethernet connection out there, and the wireless signal is too weak for it to access the internet. A solution would cost me about $150, and it is just not worth it. The system eventual corrects itself and the readings are then accurate.

J

 

wow 309 kwh last week!! that is awesome. i could charge a half dozen Leafs with that. my kwh used on my Leaf for the entire month of July was only 280 kwh. and i drove 1200 miles on that.

as far as cleaning. air pollution (smog, dust, pollen, fallout from the space station or what have you) will slowly coat ANY surface. the greater the coat, the greater the block of radiation onto the panels. your installer fed u a line of bull to prevent ligation when you go up to clean them and hurt yourself in a fall.