Interesting Observation...

[FB.]

Panels all clear of snow now - here's how they look without their blanket:

 

[whinmoor]

Can you tell the panel brands or if they are monos or polys?

 

[FB.]

Can you tell the panel brands or if they are monos or polys?

In the next several days I will try to get all the details (panel type, schematics, inverter etc) and add them to this topic. I haven't had much chance to speak to the neighbours for a few months. I strongly suspect that the neighbours' 18x200W(ish) array is "rent-a-roof".

The 15x250W panels are Chinese-built mono.
The 18x200W (ish) panels look like mono (there's no "cracked" look to the cells) but the light is fading now and they might be poly; the 18x200W panels are noticably blue-tinted in comparison to the 15x250W array, as you can see in the pictures above.

Sorry that I can't provide more details at the moment, but nevertheless, there might be something going on which others can look out for on other arrays around the country - and it could turn out to be of value in areas where snow is a problem.

At the moment, I have several wild guesses in my head:
1. The bigger panels cause the snow to lay in a more fragile way (like a long piece of plywood gives way more easily than a smaller piece).
2. The bigger panels might have a smaller rim around the edge, so snow slides off easier.
3. The bigger panels might have slightly wider "ventilation" spacing which helps snow fall off.
4. The layout of the string(s) and/or bypass diodes could be affecting heat accumulation/disipation.
5. The panels have different coatings on the glass.
6. A flock of birds landed on the 15x250 array and dislodged the snow. Given the way the snow remains on the middle panels though, I can't see this as being the cause but you never know.

 

[Yanman]

I have an observation...... Oh the joy to to have such straightforward roofs to install pv as those!!!!!!

 

[SolarCity]

I have an observation...... Oh the joy to to have such straightforward roofs to install pv as those!!!!!!

I know! The easiest to survey, the easiest to install. So very rare over the last few weeks.

 

[Silly Sausage]

I have an observation...... Oh the joy to to have such straightforward roofs to install pv as those!!!!!!

Unlike this one near me, roof facing due East!



There's another panel out of view behind the small gable!

 

[Yanman]

Absolutely. I have been trying to figure out how to fit 2 rows of 250w panels on a roof 5.8 x 3.2 to make 3kw. Apparently another company can.

 

[wstevew]

Could it be because the one on the left started feed in.

My panels were covered in snow about 10mm this morning and the inverter started feed in. When I left if was producing 150w and looked like it was starting to melt.

 

[FB.]

Could it be because the one on the left started feed in.

That would mean quite a difference in performance, considering that the two arrays "on paper" are very similar.

When the picture was taken (about 9.45-10am), the inverter for my array (the 15x250W) was outputting at a rate of about 1.8kWh per hour, compared to usually putting out about 2.2kWh per hour in similar sunlight conditions recently when there wasn't snow partially obscuring the panels.
It had been generating at about 0.5kWh per hour when I crawled out of bed around 8.30am this morning (suffering from man-Flu).

With two panels completely covered with snow and with six other panels slightly impaired (let's say equal to one more panel of complete obstruction), that's only 12/15panels (80%) of the area functional, yet the system was generating 1.8/2.2kW (82%) of the output that would have been achieved without snow.
So the loss of output from shaded/snowed-in panels - even considering the strings and the active bypass circuits on the panels - seems to not be nearly as bad an effect on other panels in the same string as many people suggest.

 

[Octopus]

More likely one house has better insulation than the other.

Or one house has the thermostat set higher than the other. lol

 

[solarsavings]

I've seen hot spots on my own Kioto modules, which is strange as they're supposed to have anti-hotspot technology. Anyway the modules showing heated cells clear quicker than the others.

 

[moggy1968]

it's not to do with insulation or the temperature in the house as the amount of snow on each roof is about the same. The most likely explanation is that good quality panels come with a hydrophobic coating on. this gives the panels a degree of self cleaning ability which will also reduce the adhesive force between the snow and the panel. Cheap panels either have no coating or an inferior coating. After several years in the optical industry I have seen good quality coatings and bad ones (from the opticians you shouldn't have gone to mostly!) and there is a considerable difference between the two. A good quality coating requires a high level of technical expertise and expensive equipment.
This is one of the things you pay for on a better quality panel
of course I may have my humble pie with ice cream if they turn out to be the same make of panel but thats my view of it.

 

[Vegelen]

The house on the left could have Suntech 250W hydrophobic coated solar panels, where as the one on the right doesnt.
Either that or Santa polished the panels on the left with Pledge, because he had no chimney to climb down, whereas the house on the right has a tight chimney and he probably ran out of time, trying to squeeze himself down on his alloted delivery slot

 

[wstevew]

They look like my suntech panels. Mine didn't clear like that, I had a day of zero output. But my roof isn't quite as steep. But the snow did slide off by the next day.

 

[danesol]

What would be interesting is knowing the generating figs for both systems at this point in time.... this may also indicate or give you better info for clearer assumption to be made as to what is really going on here and why one system is cleared of snow and the other not, up and above other contributing factors like better loft isolation, heating on higher etc etc