Thanks for that info Brett, it is appreciated

It has enlightened me, and I am sure that it will be of interest to others

Hi

Terry said "I have increased the output of just washed panels by 50% by applying cut and polish after the wash."

What can you say to that ??? What a load of tosh ! Magic polish

Thanks to The Dogs House for an informative report on how to do it properly.

Jaahn

-- Edited by Jaahn on Wednesday 5th of April 2017 10:41:39 AM

Just took a photo of the brush that is ideal for cleaning your solar panels...

Best features are a telescopic shaft, soft flock brush and a tap on the end to allow easy on/off of the water supply....

Brand is Sabco

Model - Bulldozer...

There are probably a few variations out there similar and they will all do the same job, this is my preference for the job...

I tough that glass was harder than any cut and polish car product
I might be wrong


Cheers John

Thanks Brett and Lynne and Finn,
My house panels instructions say " Correctly shut down system " prior to any maintenance including cleaning. Your thoughts on that please. cheers Craig

Hi

I have cleaned my house panels a couple of times over the years. Mostly because of bat/bird sh*t. I always did it when overcast and used a simple detergent and mop and then hosed it off well after. A scrubbing brush if needed for the blobs As the panels are at 35deg they drain well and as the sunlight was low they did not dry quickly. I like the idea of the squeege to dry them off. Thanks.  I did not notice any great change to the output either, and I look at the meter every time I walk out the door.

My several sets of portable panels are washed occasionally if I think they need it and they are near a hose. I monitor their output too and never noticed any improvement that stood out. I always keep an eye on the output to see problems that may be coming. I might look at the panels on the MH soon to see how dirty they are as they have been up there for several years now and always exposed. Still putting it out OK though.  I would not use cutting polish on my panels ! But I accept that if panels have been under a tree or the like for some time they may need some more vigorous cleaning than straight water. 

I am not an expert, just an old fart with common sense and plenty of technical knowledge and experience. So I see some statements on forums that in my opinion are good, or alternatively seem exaggerated, or again sometimes just BS. I make up my own mind, so can you ! That's life in the real world Sometimes I make a comment, that's life in the forums

Jaahn 

-- Edited by Jaahn on Thursday 6th of April 2017 11:05:15 AM

Thanks Jaahn, as you said, it comes down to common sense...

Hence no chemicals on the roof, just adds to the problems on safety and also potentials for hurting the panels long term...

Hard packed on dirt and bird crap is usually handled by soaking the panels, takes time, but it is very effective.

It varies.

I've used panels since the late '60's b4 coming to this country.

On the yachts. we cleaned whenever in port and near hrbr.
Solely cause of salt build up on fixed panels.
Mainly on framework at stern.

Caravans.
It Rains. Mine flat. get washed.
40 yrs.
I think I've touched them twice when up there doing work.
Never noticed any difference to output.
Always floating by 11-12 mid day.

over 10 yrs on home. Angles North and East.
It and Evac Tubes water system,
BOTH paid for themselves last\this yr.
Electric and hot water. ALL day. FREE...

Never been touched, cleaning wise.
But probably, if living in a dusty area we'd have too.

Unless you living in dirty air. City etc.
I wouldn't think it would make enuff difference to be noticed.

unless you one of those who sits on Gauges measuring every minute milliamp.

Last time I looked at roof system Inv was last week. Power cuts with end of Cyclone
Prev. Last Cyclone.
We still getting our cash returns every yr so somethings good hey.

Down from a Grand to $576 last yr.
That's how much the running cost have gone up over 9 plus yrs.
Near $500 on our sized system.

On a sunny day it runs the whole house. Pool pumps.
Air cond and still trickling cash into grid (2 person home 2 story)

When cold (winter coupla weeks) Heater runs 24\7 for around 5\6 weeks or so.

Warm. Aircond runs, again 24\7 for coupla months
I keep a Steady 25\26deg all yr.
And at that. we still get those returns. Chuffed.

Seems to be well balanced system.
We "supposedly" good on this 44c per kw till '28.
So I'll probably be well gone by then hey.
Little jar of dust.
OH.
When washing van I'll point the hose over roof for a tic, that's it.Normally coupla times a yr.

-- Edited by macka17 on Thursday 6th of April 2017 05:04:56 PM

I have a Bushtracker in the yard at the moment with a solar charging problem that wasn't a problem 12mths ago. Progressively over the last few weeks travelling from Sydney to Mannum SA the lithium batteries have dropped from 100% SOC to 65% SOC yet in the past the solar has kept up without a problem. A trip up the ladder and the problem is self evident. When I get to that part of the job I will post photos of the panels before and the charge rate recorded on the Victron BMV and again afterwards, just so all can see the difference in the look of the panels, what the polish rag looks like even though the panels were thought to be clean and the charge rate after cleaning.
I honestly didn't believe it would make that much of a difference either so I was out to prove the improvement was negligible and solar panel cleaning companies were a bit like Australian elephant attack insurance policies, a bit of a con unless they was a decent sized bird signature on the panel. I was forced to accept that proper solar panel maintenance was a must rather than a fluffy feel good thing. Recently (within the last 12 mths) there was a paper about the damage caused by dirt film built up around the framework of fixed solar that relied on rain to clean the panels, anyone interested will probably find it with a well worded Google search. Those interested may also see there is a large number of S/H grid tie panel appearing on evil bay lately where they have been "upgraded" due to falling output so it isn't imaginary.

As far as the solar panels that power many of the Govt utility devices in outback areas, someone who has the contract to replace the panels every 5 yrs has offered them to another acquaintance for his off grid solar upgrade, it will be interesting to see just what they are and how much output they still have.

T1 Terry

What are you doing still out of bed Macka, I'm still working so I don't have a choice :lol: Just about all my solar work is with RV's and they drive them in some real dusty places, so when it rains the dirt doesn't wash off cause they are flat mounted. The layers just keep building up, a close inspection of just about any flat mounted solar panel will show the brown or black build up around the edges and an even closer inspection will show the black spots all across the panels as well. They really show up once you start polishing them.
I'm guessing that 2.2 amps from the 40w panels is short circuit, I have 11 x 70w panels that date back to before BP entered the solar arena when the company was still Solarex. They still work ok and are within the expected output range, but output to area they aren't in the hunt compared to the Chinese stuff available these days at less than $1/w.... who would have believed they would be so cheap, especially compared to what a dollar bought way back then

T1 Terry

I don't sleep much Terry.
Normally catch up every coupla days.

Hoping this implant would help.
But not so far. Pain Yes. Sleeping ?????. We'll see.
Those 40w were rated 2.2A Outputs from new.
Still giving 2.1ish on reg and Multi.
Does enuff to slowly raise v in a battery read from Multi when I connect
so there's some output there.
Plus not draining boat batt's yet..

Yep Mobile\Dirty they do need cleaning.
But regularly "weather" washed like on my van and house up here.
Never touched. still full (theoretical) output showing in system.
House over 9 yrs. But we do get HEAVY rain when it does. Regularly.
Maybe I just picked the perfect spot to retire hey.
It is for everything else.

The old BP\Solarex. discs go black from centres out. b4 calking.
This second panel going that way too recently.
The old Solarex Factory wksp's were in Northern Adel in those days.
A fishing mate worked there
He the one told me about the bridging.
and through glass repairing to keep 'em going.
There were a LOT of older Solarex floating around in those days.
One side shorted. $20 ea, 6v Output.
Buy a doz or 2. Take to shack. double them up and away you go.12v system.
Area needed wasn't a problem. Good sun down there.
And make good Barby benches when dead. Completely weatherproof.
One lad made a carport frame. legs and top.
Covered completely in 6v panels over coupla yrs. Ran both shacks on it.
and kept ute under.
40\to 60w were biggest avail in those days.
My first was a 5w. ONLY ones avail.

Oh and some old Telstra units that appeared at boat club one w'end.
Spindly looking things they were hey.
handful of round discs on a blue glass plate.
Basically.

Yep. Sure have come on in technology.
and even Chinese Quality seems to be improving
with the QC in latest factory's.
It's interesting to watch them assembling on net.

While at the Stone The Crows gathering I was asked to check why a solar set up was not keeping the batteries charged and they had dropped to 11.5v after only 2 days. A check of the panels and they were covered in dust that had been wet over night and now dried on. It was yet another chance to test the wash with water only against polishing afterwards. A wash and chamois dry improved the solar output by 50%, 1.5 amps increased to 3 amps, not very good for 2 x 150w panels. Polished the panels with Repo no2 cut and polish, no improvement on the first panel but the second panel the input went from 3 amps to 7 amps, that's better than a 50% improvement. Unbolt the panels to see why there was no improvement from one panel, wire broken off at the large BP connector join but also discovered the wiring from the roof to the controller and on to the battery was 2.5mm sq conductor.... caravan manufacturers simply don't have a clue when it comes to solar wiring. Connected the second panel and the output was now only 7.5 amps, not the expected 14 amps, disconnected the first panel and the output of the panel with the previously broken wire was 7 amps, yet both connected only 7.5 amps, that was all the 2.5mmsq cable could carry. Plugged 2 folding 100w panels (2 x 50w x 2 sets) into the Anderson plug that went to the fridge and from there to the house battery (again another example of clueless caravan manufacturers) and the output from the 200w was 12.5 amps.... because the cable was heavier.
It got them through the week as there was no power available that far out and they both had CPAP machines that ran at night off the inverter, the fridge was on gas fortunately.
This improvement from just washed compared to polished was witnessed by quite a few interested parties and they confirmed it to the group gathered for the solar and wiring talk a few days later, so it's not something I just made up, it has been verified more than once to a lot of different interested parties, it really does make a difference.

T1 Terry

oldtrack123 wrote:

---

 

Perhaps what you should have said that while the 2.5 mm Cross sectional area cable could carry up to up to around 26A  without overheating, due to run length & perhaps some other factors , [such as panel output voltage]  VOLTAGE drop was the problem!!!

It would be interesting to know just what the voltage drop was in the circuits

Especially if you are giving a talk on electrical matters ,wiring etc

-

-- Edited by oldtrack123 on Saturday 13th of May 2017 08:53:24 PM

---

I'll let you do your own testing Peter  The thing most people including those electrically trained fail to keep in mind is solar panels do not have to put out any current, so it is not really voltage drop that is the problem, it is how high the voltage is held at the solar panel. The Vmp at the solar panel for the average 12v nom. cell is between 16v and 18v @ 25*C, solar panels in the Aust sun are unlikely to remain at 25*C so the Vmp must be derated to match the internal temp of the solar panel.

This graph from Kyocera shows the effect  temp has on output

From the chart you can see that at 25*C the current output starts to drop off at roughly 17v, but at 50*C the current starts to drop off at just below 15v. If the target voltage is 14.8v before the end of bulk charging is achieved there is only a margin of 0.2v between the point were the panel simply reduces its output. At the 17v mark with the panel's internal temp at 50*C the output has dropped by 25%, so as you can see it doesn't take much resistance in the solar wiring to seriously effect the total harvest available. It is not unusual where poor cable sizing has been use to see 16v plus at the panels, the output of the panel has already started to drop off at this point, does this make the panel get even hotter? Perhaps Peter can enlighten us, he has expressed an opinion on this subject on another forum so his response will be interesting 

 

T1 Terry

Izabarack wrote:

---

Same Telstra tech wants to know the physics behind a 100 Watt panel suddenly putting out 150 Watts following a cut-n-polish. I'm not sure that is what was meant but if a washed panel is putting out its spec in full sun on a mild day and after a wash, why would anyone give them a cut-n-polish?

Iza

---

 Good question Iza.!

Of course the BAD effects of a  regular cut & polish may not show up for years , and the degrading then would no doubt be claimed to be due to aging

-- Edited by oldtrack123 on Sunday 14th of May 2017 09:31:39 PM