Odd questions about PV panels

System

I'm sooo glad I found you guys as I have a few questions that may seem strange but are very important if I decide to take the plunge into solar pv.

1. Is the front surface of all pv panels made from normal glass?
Reason: I/we will have to drink what comes from the roof.
2. Are the edges made from aluminum stock? What is the back made from?
Reason: My mounting may be very unusual.
3. Would the output on a cloudy winter day (Dec 21) be in the range of 10% of max rating?
Location Cincinnati (39 degrees)

crewzer

Re: Odd questions about PV panels

Check the specs on PV module cut-sheets for mechanical specs. For example, the Kyocera KC-130 uses low-iron tempered glass, EVA material for the backing, and an anodized aluminum frame. See: http://www.kyocerasolar.com/pdf/specsheets/KC130TM.pdf

Once illuminated, a PV module's output voltage doesn't vary a whole lot, although voltage varies inversely with PV cell temperature. Output current varies fairly linearly with insolation, and simple trigonometry can be used to estimate output current from off-axis applications (both elevation and azimuth).

Available power output on a cloudy winter day will likely be quite low... somewhere in the range of 5% to 10% of spec.

HTH,
Jim / crewzer

System2

Re: Odd questions about PV panels

samkent wrote: »

I'm sooo glad I found you guys as I have a few questions that may seem strange but are very important if I decide to take the plunge into solar pv.

1. Is the front surface of all pv panels made from normal glass?
Reason: I/we will have to drink what comes from the roof.
2. Are the edges made from aluminum stock? What is the back made from?
Reason: My mounting may be very unusual.
3. Would the output on a cloudy winter day (Dec 21) be in the range of 10% of max rating?
Location Cincinnati (39 degrees)

1) Most use a low iron glass. I can't imagine that causing any health problems, except for the bird and insect droppings that will wash into your drinking supply.
2) Most do use an aluminum frame. What is the back made from? I can't answer that one. Probably differs, depending on maker and age.
3) That totally depends on how thick the cloud cover is. Some days with light cloud cover, I get perhaps 40% output. However on other, heavy overcast days, I get nothing. There is no firm answer, it completely depends on the cloud cover. Winter, or summer differences you will see are that on a cold day, the PV output voltage will be considerably higher than during hot summer weather. Cold is good, as is naturally reflected light from the snow cover, even on a cloudy day. The length of the day however, and the tilt of the PV,s greatly affect the DAILY TOTAL output.
All the best
Wayne

Roderick

Re: Odd questions about PV panels

I'm certain the whole arrangement is non-toxic, for just the reason you suggest - some people will do water catchment. As long as you're getting recently made panels and not old, used ones, even the connections should be lead-free. Our panels have a "Pb" in a crossed-out circle to signify this.

In Cincinati, you'll have to think about shedding the snow off the panels, too.

As to the output on an overcast day, it can be virtually nothing. On a dark and rainy December day, we got less than 1 kWh total, where just a few days before, we got 16 kWh. If your panels are covered in a thick layer of snow, count on output being nearly zero, too.

The tilt makes a big difference in Winter performance, assuming you have a clear day. That 16 kWh day could have been 24 kWh for us, if the panels were tilted optimally for winter. But our panels are on a fixed mount, matching the roof pitch.

mike95490

Re: Odd questions about PV panels

Lead free panels. Sounds like a great idea, and I hope they work, because I suspect in a couple of years, all the new gadgets being built with lead free solder, may start failing, due to faulty solder joints. Panels should have a 20+ year warranty, and with all the hot/cold day night cycles, that may start to take a toll on them. The exact magic that lead performs in a solder connection, even at 10%, is not well defined, and that's why it hasn't had a good replacement found.

But as to collecting water off panels, they are built to last, and inherently, to last, it should not shed anything. Low iron glass, anodized aluminum frames are fine, but all the nasty dust and bird poop, I might water a garden, but not drink it.

System2

Re: Odd questions about PV panels

Just a note on tilt. Here in Nova Scotia, this time of year the sun is quite low on the horizon and I find excellent results with the panels tilted almost vertically.
1) The sun is low on the horizon.
2) Snow won't collect on the panels.
3) A big output gain, as much as 30% from the light reflected off the snow covered ground, a gain greatly appreciated during these short winter days. It's much like the cloud edge effect, only stronger and lasts all day.
That's my experience anyway.
Cheers
Wayne