solar panels with diodes between each cell

Well... That would be a bypass diode, which would be in parallel with each cell, not between each cell. That also appears to be discussing a different panel from the one you posted.

pianotuna wrote:

FWC wrote:

theoldwizard1 wrote:
A typical diode loses 0.7V !

Yeah, something definitely doesn't add up here. Each cell in a solar panel only produces 0.5 - 0.7V (they are in fact diodes). The forward voltage drop on a diode is between 0.2 and 0.7V so you would loose half to all you voltage if there really was a diode between each cell.

Now, maybe he meant to say there is a diode in parallel with each cell, which would provide a bypass diode for each cell. This would provide slightly better mottled shade tolerance, but would increase the complexity of the panel. The linked data sheet doesn't mention this, so it seems unlikely to be true for those panels.

Then please explain this link?

https://www.pveurope.eu/solar-modules/each-cell-bypass-diode

From the link:

"The AE Smart Hot-Spot Free solar panel by AE Solar is unaffected by shading. Each of the 60 or 72 cells of a panel is protected by its own bypass diode."

So what does your power system consist of?

Gdetrailer,

I don't know how they are doing it or what diodes they are using. However, they are producing them.

FWC wrote:

theoldwizard1 wrote:
A typical diode loses 0.7V !

Yeah, something definitely doesn't add up here. Each cell in a solar panel only produces 0.5 - 0.7V (they are in fact diodes). The forward voltage drop on a diode is between 0.2 and 0.7V so you would loose half to all you voltage if there really was a diode between each cell.

Now, maybe he meant to say there is a diode in parallel with each cell, which would provide a bypass diode for each cell. This would provide slightly better mottled shade tolerance, but would increase the complexity of the panel. The linked data sheet doesn't mention this, so it seems unlikely to be true for those panels.

Typical diodes do drop nominal .7V, but Shottky diodes only drop about .3V.. Kind of doubt they would have used Shottky diodes but maybe perhaps they are, who knows..

So in reality even with parallel diodes were across each cell and you have 36 cells that would be 25.2V of voltage loss which basically eats ALL of the voltage produced by at least TWO of the series panels..

Now if they were Shottky diodes you would fare a bit better as that would be about 10.8V loss, but even that means you would need a series string of at least 3 or more panels just to get to some semblance of a charging voltage for 12V..

Realizing that would be worst case with one full panel completely shaded but still I don't think your going to see a very large difference if the panel has parallel bypass diodes or not..

Better yet, is to not park or place panels where that kind of shading may happen..

FWC wrote:

theoldwizard1 wrote:
A typical diode loses 0.7V !

Yeah, something definitely doesn't add up here. Each cell in a solar panel only produces 0.5 - 0.7V (they are in fact diodes). The forward voltage drop on a diode is between 0.2 and 0.7V so you would loose half to all you voltage if there really was a diode between each cell.

Now, maybe he meant to say there is a diode in parallel with each cell, which would provide a bypass diode for each cell. This would provide slightly better mottled shade tolerance, but would increase the complexity of the panel. The linked data sheet doesn't mention this, so it seems unlikely to be true for those panels.

Then please explain this link?

https://www.pveurope.eu/solar-modules/each-cell-bypass-diode

From the link:

"The AE Smart Hot-Spot Free solar panel by AE Solar is unaffected by shading. Each of the 60 or 72 cells of a panel is protected by its own bypass diode."

So what does your power system consist of?

theoldwizard1 wrote:
A typical diode loses 0.7V !

Yeah, something definitely doesn't add up here. Each cell in a solar panel only produces 0.5 - 0.7V (they are in fact diodes). The forward voltage drop on a diode is between 0.2 and 0.7V so you would loose half to all you voltage if there really was a diode between each cell.

Now, maybe he meant to say there is a diode in parallel with each cell, which would provide a bypass diode for each cell. This would provide slightly better mottled shade tolerance, but would increase the complexity of the panel. The linked data sheet doesn't mention this, so it seems unlikely to be true for those panels.

theoldwizard1 wrote:
A typical diode loses 0.7V !

Exactly why I went series/parallel for a nominal 33 volt input.

A typical diode loses 0.7V !

2oldman,

Unisolar panels had diodes between each cell--it is one reason my system punches above its weight.

Very interesting. TY

Another thing happening is the increasing number of busbars in a cell to collect current. Used to be mostly two. Then there were three. I see one now with six. Efficiency 20% instead of 15% (Efficiency means panel roof space taken up per watt)

".... which enables particularly high performance on a small surface. Q.ANTUM’s world-record-holding cell concept has now been combined with state-of-the-art circuitry half cells and a six-busbar design, thus achieving outstanding performance under real conditions — both with low-intensity solar radiation as well as on hot, clear summer days."