PowerSwitch

So, 2 pm and the snow's stopped and out comes the sun. Out also comes RC with her trusty broom and sweeps the snow orf the PVs as per. And watches the power change from zero to...zero!! Yesterday at about the same time, it was 860W.

So I ring up my mate the Green councillor down the road and lo, they're on zero output as well! I also ring up the installers. They say that, assuming we haven't both developed a fault (unlikely) it might be a matter of poor air quality. This isn't one I've heard before. We're just downwind from an AQMA (air-quality blackspot) and Solar PVs work on red and infra-red afaIk.

Anyone else seen this effect?

[quote="RenewableCandy"]

Could it be transparent ice on the panels? Water is opaque to infra red.

I doubt it though - PV is usually optimised towards the blue end of the spectrum as this provides more power. Expensive multi-layer PV has multiple junctions, each optimised to a different light colour.

Maybe you have ice in your charge controller and it is simply not woken
up.

Problem solved: panels are wired in series and ALL need to be de-snowed (see other thread)

Not in Colorado. Of course, we have clean air, so I'm not familiar with what dirty air might do to the panels.

Enough of that!

I've been to Denver, so I know THE TRUTH .. sheesh, the cheek of these colonials ....

RenewableCandy wrote:Problem solved: panels are wired in series and ALL need to be de-snowed (see other thread)

That sounds like a oversight. Panels need to be wired so they can work independently of each other, some kind of bypass diode, though adam2 would probably have the correct term. What if one panel simply fails, which is possible?

For some reason, your set-up doesn't sound right, RC.

Candy,

If the panels are in series that means the output voltage for each panel is added together. Individual panels are usually 12 or 24 V. What is your inverter/ charge controller rated at ?

My panels are 24V. A higher voltage needs less expensive wiring, but you lose all power if one or more panel is overshadowed (or snowed on).

RC clears her roof to get her PV working
http://www.youtube.com/watch?v=s5lcX_M9AmI

[quote="RenewableCandy"]So, 2 pm and the snow's stopped and out comes the sun. Out also comes RC with her trusty broom and sweeps the snow orf the PVs as per. And watches the power change from zero to...zero!! Yesterday at about the same time, it was 860W.

Sure it's not just the panel temperature after you cleared the snow off?

I believe temperature does affect the panels, mine take a bit longer to start producing at the moment, with overnight temperatures at -14 I don't blame them....

I let nature and gravity take it's course to clear my panels, 6 on top of the dormer still have snow on them, My panels are linked in 2 strings of 10, 2 of the covered panels in one string, and 4 in the other. Despite this partial coverage the system managed 4kw yesterday and today, so I think this disproves the suggestion about a few shaded panels stopping all production.

Panel temperature wont be the problem, PV works better at low temperatures, it cant be too cold for PV modules.

Ive been getting 30+ amps at about 15 volts from a array with a nominal output of just under 1KW.

A very light dusting of snow, or light frost cover can reduce the output substantialy, and as posted above, snow cover can virtually eliminate it.

JohnB wrote:RC clears her roof to get her PV working
http://www.youtube.com/watch?v=s5lcX_M9AmI

The Glaswegian accent's a nice touch!

Brilliant video and I understood every word !