Bypass Diodes

[Mike90250]

Wood for signs is one thing.
Wood frames with glass and sealed in PV cells is a solar oven, and will cause the problems I listed earlier.

[Zardiw]

More $0.02: While wood is a fine material for many applications, my experience is such that it's particular characteristics, one of which, BTW, is relatively good thermal insulating qualities compared to most metals, make wood less than ideal for solar panel applications, either for module framing or panel/array support, pretty much regardless of surface coating or other treatment.

I have to agree.......The problem with wood is if you get a Hot Cell......it will Burn the wood possibly starting a fire.....

He did say he was going to use layers of foil and heat resistant paint......but it will still trap heat and possibly char/catch fire.

And all the trouble and expense........I think it would be way better to just use glass.............z

[Guest]

ya glass underneth the cells would work wonders. im sure I was thinking that to.
Anyway im off to next town where they have dollar store and grabbin 60 more of these tiny cells. will be back in 2 hrs

[Zardiw]

Got my ByPass Diodes!.. (SBR12U45LH -13)......They are awesome. Will add them to my second panel.

Here's the spec sheet on them from Mouser: http://www.mouser.com/ProductDetail/...2bjUGdJbh3w%3d

They are really thin and will work great between the glass sheets.

Am also in contact with MicroSemi who just came out with a 'Smart' surface mount type bypass diode that is only .7mm thick. and designed to be incorporated inside panels.

z

[inetdog]

... you should heatsink them - don't forget their case is electrically live.. With .63V @ 7.5A, you will be dissipating about 5 watts per diode, so chose a heatsink accordingly, strive to keep junction temp below 90C, sure their spec is 150C, but they won't last long that hot.

Which is why the bypass diodes are most commonly located in the junction box rather than sandwiched into the panel at some other location. Even in the junction box the manufacturer typically relies on the wiring to conduct heat away rather than take the cost and space hit of a heat sink.

[Zardiw]

Which is why the bypass diodes are most commonly located in the junction box rather than sandwiched into the panel at some other location. Even in the junction box the manufacturer typically relies on the wiring to conduct heat away rather than take the cost and space hit of a heat sink.

Well these are specifically designed to be sandwiched......hence their thinness. I've already started leading them with bus wire....pretty sure that will adequately transfer any heat away from them very well. There IS a center square on them that may be designed for a heat sink.....but I'm not planning on using it. Also they're rated to 200C.......fwtw........I doubt the panels will get that hot........will see......in the Summertime it can get up to 120F here in Palm Springs.......which is only 49C...But in the sun I suppose they will get a lot hotter.....I had some copper heating coils in a glass box and it got up to 188F ....which is only 87C.

Hoping there won't be any really hot spots. This first panel is made with factory reject cells.....I've tried to use the highest output ones....Guess we'll see how it turns out...........z

[Mike90250]

If the diodes are not properly heat sinked at their heat sink terminal, they will overheat. Tab wire is too thin to carry much heat, maybe 2 or 3 layers will give enough copper to carry heat away. The diodes only get used if a portion (not always where the diodes are located) of the panel gets shaded