solar panels with diodes between each cell

2oldman wrote:
OK, it's panel. Not sure if the Canadian spelling is pannel.

nope I just suck at spelling, but if you have nothing better to do then look for spelling errors you need another hobby.

Not on subject, but thanks for that post BFL13. I am one that struggles with the English language, being it Australian or American and often feel intimidated by some peoples comments. I on the other hand try not to make to much fun of other people trying to write or speak Danish.
Frank.

I was also wondering what the application is for this panel. If the cost is very low then it would be a great panel for RVs. If the cost is significant then maybe not for most RVs.

And panel life? If the diodes are imbedded and not replaceable then a single failure could result in a shorter panel life.

CA Traveler wrote:
Here's a graph of my 3x serial panels with 9 bypass diodes and each diode string is about 10V. Note how the panel voltage increases by 10V as the leafy shade moves off of the panels. For me if there is significant cost for a bypass diode for every cell then I would not be interested. Also mine and the common panel arrangement has the diodes in the junction box so easy to access if necessary and limited cost. Individual cells not so much.

With shading on one string my output is 8/9, 2 strings it's 7/9, etc. While there is an additional voltage drop of about 0.3V for the conducting diode that's rather limited.

Great example!

I would think that with diodes on every cell (instead of ever 18 or so) you would have a smaller steps in your 'stair step', and maybe a small increase in energy depending on the pattern of the shading. The tradeoff is of course the diode drop. With your configuration you instead of gaining 10V from the shaded cells, you are loosing 0.3V. With a diode every cell, instead of gaining 0.5V from each shaded cell you are now loosing 0.3V from each cell.

There is a reason very few manufacturers use a bypass diode per cell as opposed to the number of diodes required to avoid 'hot spot' damage. Unisolar pretty much had to as their thin film panels are inherently more shade sensitive, I am not sure why this company is doing it.

2oldman wrote:
OK, it's panel. Not sure if the Canadian spelling is pannel.

His computer does not do spell cheques. :)

Now can we get everyone to stop saying "lay" instead of "lie" and VV? Then we can work on "careening" when they mean "careering".

Or just ignore it. Some of us got our Grade 6 before being expelled, but not all.

Note: Mfgs do not install bypass diodes for panel output in shade. Instead shaded cells without bypass diodes create a hot spot due to reverse biasing from other panels. Without bypass diodes the cells can be damaged and even catch on fire.

Here's a graph of my 3x serial panels with 9 bypass diodes and each diode string is about 10V. Note how the panel voltage increases by 10V as the leafy shade moves off of the panels. For me if there is significant cost for a bypass diode for every cell then I would not be interested. Also mine and the common panel arrangement has the diodes in the junction box so easy to access if necessary and limited cost. Individual cells not so much.

With shading on one string my output is 8/9, 2 strings it's 7/9, etc. While there is an additional voltage drop of about 0.3V for the conducting diode that's rather limited.

72 cell panels are about Vmp=39V and Voc=46V. CCs need to handle this including variations for temperature. Most important for me was the size - 39"x79" and as a result I used 60 cell panels. Plus 3 series panels and my 150V CC maximum makes the Voc marginal, and perhaps out of spec considering temperature.

I have known about diode panels for a long time. the problem is that the diode has a slight voltage drop so you need more solar calls to hit the magic charging voltage. the advantage.. If the panel is partially shaded. the rest of it works still. that's a MAJOR advantage for folks who sometimes park where it's not 100% sun.

OK, it's panel. Not sure if the Canadian spelling is pannel.