solar panels with diodes between each cell

[pianotuna]

Hi folks,

I stumbled across these panels today:

https://ae-solar.com/wp-content/uploads/2018/10/AE_P6-36_155W-175W.pdf

They apparently have diodes between each and every cell which gives them an advantage for series connection of the panels (i.e. shade tolerant)

Does anyone know of other panels that do this?

[2oldman]

StirCrazy wrote:

where did you read about the Diodes, I cant find anything in the link you posted.

I can't find that about those panels either.
And the full specs are listed for only one type of panel.

[StirCrazy]

pianotuna wrote:
Hi folks,

I stumbled across these panels today:

https://ae-solar.com/wp-content/uploads/2018/10/AE_P6-36_155W-175W.pdf

They apparently have diodes between each and every cell which gives them an advantage for series connection of the panels (i.e. shade tolerant)

Does anyone know of other panels that do this?

where did you read about the Diodes, I cant find anything in the link you posted. Most solare pannels have bypass and blocking diodes, which allows sections to be bypassed in shady conditions or what ever. the lower end only have 3 and higher end ones have more. the cost of adding the diodes is pretty substantial, so if some one is putting them on every cell that would be wild but I wonder how much of a difference it would be from say every second or every 3rd cell.

for me its a 12V pannel so I am not sure I would realy look at it for use, 24V pannels let you run smaller wire and such. but I also have a split cell pannel and they are touted for being more efficient in low light and partial shading situations so dues to the smaller cell design allowing them to have a slightly higher output per cell.

doing some more digging into this my split cell 24V pannel has a bypass diode for every cell, which is why thes pannels are so good in partial shading so I guess that must be becoming a pretty standard thing now.

Steve

[pianotuna]

CA Traveler wrote:
Bypass diodes for shading of parallel panels have limited advantage. Each shaded cell loses 0.5V + the diode loss. So that panel is under performing other non shaded parallel panels perhaps significantly.

It does not appear these panels are physically larger than ones that don't have this feature, and 300 watts is 300 watts no matter where it is coming from. There are a few you tube comparisons of output between this tech, and the more common 3 or 6 diode units.

What I can't find so far, is a price.

[pianotuna]

FWC wrote:

pianotuna wrote:
FWC,

I'm still waiting to hear about your power system.

I am not sure why this is relevant.

It is relevant because it would help others understand your approach to mobile power.

For example, I prefer a larger than usual battery bank that can be used at extreme temperatures. The OEM bank was about 375 amp-hours which I immediately raised to 875 amp-hours. I would certainly never consider a 200 amp-hour bank, but that might be lots for many other end users.

2oldman has jumped to a 48 volt battery bank--which means he may likely have a DC 48 to dc 12 device of some kind. He has gone from 12 to 24, to 48 volts. He is expert at winnowing out searches on RVnet

BFL13 prefers a minimal approach to solar and is willing (or once was) to tilt and twirl his panels. He even experimented with a fixed tilt tracker. Quite a creative thinker of the "out side the box" variety.

If one knows the context from where the other person is speaking it is easier to understand what they are trying to share.

[CA_Traveler]

Bypass diodes for shading of parallel panels have limited advantage. Each shaded cell loses 0.5V + the diode loss. So that panel is under performing other non shaded parallel panels perhaps significantly.

Definitely better performance with each cell having a bypass diode and a single panel or series panels.

[CA_Traveler]

The typical panel has 1 bypass diode for each string. A 4x9 panel has 2 strings 6x10 has 3 strings. And these diodes are external to the cells and in the wiring box which is close to the junction box. From the diagram above 2 more wires are routed to the junction box for the 3 diodes.

My 60 cell panels have 3 byass dioes or 1 for every 20 cells which is 10V. With 3 panels in series each string has 10V. I've previously posted a graph showing a rising sun with leafy shade on the panels. Charging starts at 20V and jumps by 10V increments as the shade moves off of the panels. My diodes have a 0.3V drop so very small effect.

[rlw999]

FWC wrote:

rlw999 wrote:
There are specialty low loss "diodes" made for applications like this. They aren't traditional diodes but use a controller that switches a MOSFET. Essentially it acts as a switch that turns on when it senses forward voltage and off when it senses reverse voltage.

Here's an example that has a 26mV forward voltage.

Bypass diodes can use standard P-N or Schottky diodes, they are only forward biased (on) if a cell/string is shaded to allow the current to pass around the shaded cell. Definitely no need for a MOSFET 'ideal diode'.

They can, but as I said, there are specialty diodes made for applications like this that limit the power loss due to high forward voltage. The manufacturer even says that's why this product was developed:

Texas Instruments SM74611 Smart Bypass Diode is used in photovoltaic applications and provides an alternate path for string current when parts of the panel are shaded during normal operation. TI SM74611 Smart Bypass Diode has a lower forward voltage drop than PN junction and Schottky diodes. It has a typical average forward voltage drop of 26mV at 8A of current. This translates into typical power dissipation of 208mW, which is significantly lower than the 3.2W of conventional Schottky diodes. The SM74611 is also footprint and pin-compatible with conventional D2PAK Schottky diodes, making it a drop-in replacement in many applications.

[FWC]

pianotuna wrote:
FWC,

I'm still waiting to hear about your power system.

I am not sure why this is relevant.

[FWC]

rlw999 wrote:
There are specialty low loss "diodes" made for applications like this. They aren't traditional diodes but use a controller that switches a MOSFET. Essentially it acts as a switch that turns on when it senses forward voltage and off when it senses reverse voltage.

Here's an example that has a 26mV forward voltage.

Bypass diodes can use standard P-N or Schottky diodes, they are only forward biased (on) if a cell/string is shaded to allow the current to pass around the shaded cell. Definitely no need for a MOSFET 'ideal diode'.

Edit: Should have read the data sheet first - you are right they are selling these for use as bypass diodes. Seems to me that this would be more important for blocking diodes that are always in the circuit.

[rlw999]

There are specialty low loss "diodes" made for applications like this. They aren't traditional diodes but use a controller that switches a MOSFET. Essentially it acts as a switch that turns on when it senses forward voltage and off when it senses reverse voltage.

Here's an example that has a 26mV forward voltage.

[pianotuna]

FWC,

I'm still waiting to hear about your power system.

[pianotuna]

Nice Diagram Time2roll Thanks!

[pianotuna]

Gde,

As I said. I don't know the technology--but it is clear they are producing something of great interest.

Here is 85 pages of information / sales https://ae-solar.com/wp-content/uploads/2018/10/NEW-CATALOGUE-23.pdf

[Gdetrailer]

pianotuna wrote:
Gdetrailer,

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

Yep, they may be making them but the "devil is in the details".

As I mentioned, standard silicon diodes in parallel with each solar cell because of their inherent high forward voltage drop would not be of any advantage for a small series string.

each single solar cell only develop .5V but placing a silicon diode in parallel to create a bypass is going to drop .7V..

Now if they are Shottky diodes at .3V drop that might make better sense..

From my POV I suspect perhaps a large series string of panels may have a bigger potential benefit, perhaps at least 3 panels in series and more panels in series would be even better since you spread out the losses over a greater area.. But then you run into max input voltages of the MPPT controller issues..

Depends on which poison you want to take..

Not sure I would be very concerned about if the panel had them or not for series strings of two or three..

Seems to me, putting the money into a few good high wattage panels and finding a good spot with minimal panel shading through the day most likely will work just as good.

Diodes of any kind represent a loss, just can't get around that fact.

[MEXICOWANDERER]

They are marketing a circuit "diode" now. It consists of a MOSFET that blocks reverse current. They have something like .008 vf.