What a difference a few degrees makes

[dnix71]

It just rained a little bit here in south Florida and my panel output went up to 2/3's of name plate when the sun poked out again. It's almost never more than 1/2, even in
noon day sun. I have mostly those cheap HF thin film panels.

[wpowokal]

You may find it is additional reflection off the clouds rather than temperature.

[DamonHD]

I believe that I've seen the effects of both (and cloud-edge effect) on my grid-tie PV, plus some inverters can convert higher peaks of power in bursts than continuously, so all 4 can work together when coming out of a rain shower to get particularly big spikes, with my 4.1kW nominal inverters putting out 4.58kW for example...

Rgds

Damon

[hydrosun]

If you are getting less than 1/2 rated output I'd suspect some panels aren't working at all or the connections are faulty. Even without a mppt you should be getting at least 2/3 ratings in full sun all the time.  Had one system with low output and found water had gotten into the junction boxes and corroded the connections. One panel wasn't working at all and half of another wasn't connected.
So you could unhook one panel at a time and test for short circuit amperage and open voltage. If they are all close to the same then they might have been over rated to begin with.
Chris

[dnix71]

Yeah, I had a mismatch on two panels wiring, but it's still hard to tell what the peak should be, my panels are mounted permanently on angled racks and the sun is pretty high this time of year and it's almost always some overcast (which is better than no clouds here in south Florida in the heat of the summer. I disconnected three panels and the response to changes in light became noticeably snappier. I plan to remount two of the panels when I get the time later this week. I rent, not own and the landlord is working on apt 2 for a new tenant, but he hasn't said anything about the panels propped up out back. I like to keep it under the radar. I've lived here 25 years and pay the rent on time and help out with upkeep so he cuts me some slack.

Some people see what I have and think I can run the whole apt on the panels. I tell them it's for hurricane backup, which is the original reason I did this. As cheap, easy oil goes away, I've shifted focus to being able to operate off-grid permanently if there is a second Great Depression because people just don't seem to see the connection between cheap easy oil and the economy as a whole. My parents were children during the Great Depression, so I don't have first hand experience living without money or some paying job and without indoor plumbing or grid power. There has to be a way to make off-grid sustainable without becoming cave dwellers, or this decade will not end well for many people.

[Bruce S]

dnix71
I noticed the same thing after the down pour we had late this afternoon.
As luck would have it I am covering 3rd shift and was home & awake when the shower came through. Heavy enough to clean off the dust and cool them off. temp just before the winds came was 92F with a humidity index of wearing the air  .
Even with the back ground painted a flat white to keep reflective heat to a minimum the backs of the HF panels still get hot.

There have been others posting here who own or owned the HF panels with observation that the HF panels loose output much quicker than higher quality panels. I can see where the heat will do it for sure.

I have noticed that as other people begin to realize prices aren't going to come down they are finding ways to save.
I agree there should & can be ways to not becoming cave dwellers once again.
Except that caves can pretty nice places to be unless Momma bear gets there first  .

Reading how, people copped during the first one, gives pretty good insight how people just figured things out without too much outside help.
 
I'm finding it as others do these things, they figure out 1/2 the crap they were led to believe they needed they can just do without.
BUT there should be a minimum level of comfort, otherwise there's the government to turn to and I really do not want the Socialist side to become the dominant side.

Doing this that we do, Solar, wind, hydro, Bio-??, dog/human etc; also gives us a little more freedom & it is not too bad for getting up off the duff and finding a new source of fun too 

Cheers
Bruce S
 


 

[Ungrounded Lightning Rod]

Heat, dirt, cloud reflections, overcast shading.

You might want to check whether the output stayed up somewhat after the rain cleared the dust off your panels.

Next hot day, spray with a garden hose.  The boost will tell you how much temperature is a factor.

[TomW]

Next hot day, spray with a garden hose.  The boost will tell you how much temperature is a factor.

Rod;

Excellent way to prove the theory and I have seen this myself.

Tom

[tsveti]

Hello dnix71,
   I liked very much your opinion for thr future energy and our undependence. I have 4 monocrystalline  panels 90W , 17V each. I made some initial experiments and got similar results. At noon the panels are very hot and from 90W I got only about 45-50W at max power point. The temperature of the panel is above 50'C. In my opinion in the real condition we can only obtain max 60% from the panel power on the label.

[DanG]

The only way for panels to shed heat are conduction, convection, radiation.

The glass is a poor conductor of heat - and the any legs off the frame are minute compared to heated surface area.

Convection off a perfectly smooth front glass surface or the back plain laminate will be minute also.

Radiation is how panels shed most of the suns heat load - the heat energy simply beams away in infra-red like heat from a bonfire.

If you have the panel back too close to anything it just bounces right back at the panels eliminating a third or more of the heat shedding capability.  That is a built-in loss for houses that plop panels on the existing roof. Similarly, having panel rows racked too closely together can have the front row dumping to the next rows and raising those panel temperatures which beam on the next row, etc..

The stalk type panel array - umbrella, mushroom, whatever you want to describe it as - gets the panels up in some airflow and gets them away from anything that will re-reflect heat back at them. If you want to get every last possible watt from them, that is the way to go.

[SparWeb]

The only way for panels to shed heat are conduction, convection, radiation.
The glass is a poor conductor of heat - and the any legs off the frame are minute compared to heated surface area.

That got me thinking...  the OP mentioned that it had just rained.  Well water is a good conductor of heat - it has a tendency to absorb heat very quickly from surfaces it touches, and carries it away as it evaporates.  It might have helped, to rapidly cool the panels, in addition to washing off the dust as ULR mentioned, and the clouds parting...

Just a thought.