the new flexible mono panels (split from Dokio)

[frater secessus]

I split this off from the original Dokio thread to avoid topic drift.

The previous generation of flexible panel were failure prone. At least some of those problems have been addressed. Heat from surface mounting is unavoidable.

There has definitely been a shift in the last year or two.  Flex panels used to be amorphous cells, which had certain benefits. 

• lower temperature coefficient meant panel voltage was less affected by ambient/cell temperature
• long strip cells were less affected by partial shading

The move to crystalline cells for flex panels has brought the flex power/area ratio up but I don't know how much movment the silicon will take before cracking.  This old MIT article from 2008 talking about flexible crystalline panels suggests the wafers may be 1/10th the thickness of the usual wafers.  If so, maybe using thin cells in framed panels will reduce production costs?  Since output is same/similar maybe we end up in a market where all the panels are the same thin-wafer flexible, but some are left flexible and others are mounted in traditional frames.  Standardization reduces production costs?

My guess is the new flex are usually mono because of the higher Vmp.  The lack of underside cooling when surface-mounted will cause Vpanel to drop and poly might not provide enough voltage headroom for that.

Watching with interest.

 

[jimindenver]

One thing that I saw about the Dokio flex panels on the folding mat is that they were not the smooth plastic surface that I saw on the four flex panels Bob bought for use in the PWM VS MPPT test we ran. The surface of those were so soft that even using a swifter duster caused light scratching and I wasn't able to avoid it even with the rolling cloth technique I developed for my company while dusting fine finishes. With that technique the cloth is constantly rolled upward away from the surface so that the dust never builds up acting like sand paper. The micro scratches cause reflections away from the cells meaning you reduce the effectiveness every time you clean the panels.

The move to Mono and away from poly is bad and not just for the difference in the response to cloudy contions side by side testing has shown. Most of these panels are paired with a PWM that is going to shed the voltage above battery voltage. All Monos have a higher voltage and less amps that the same wattage of poly. In the end the mono losses more voltage and the amps associated with it than the poly does. The Mono may be more efficient but there is nothing more efficient about fewer amps to the battery.

This can be proven by using the simple formula or even better, side by side testing. Unfortunately that will bring a chorus of you need better PWM controllers, lab conditions where everyone lives or look at who is running the test.

 

[frater secessus]

You're right on the mark with all of that.

 

[DLTooley]

The only takeaway I have is that there has been some improvement. I am skeptic cal about how much.